Cutis

Dermatology residency positions continue to be highly coveted among applicants in the match. In 2019, dermatology proved to be the most competitive specialty, with 36.3% of US medical school seniors and independent applicants going unmatched.¹ Prior to the transition to a pass/fail system, the mean US Medical Licensing Examination (USMLE) Step 1 score for matched applicants increased from 247 in 2014 to 251 in 2019. The growing number of scholarly activities reported by applicants has contributed to the competitiveness of the specialty. In 2018, the mean number of abstracts, presentations, and publications reported by matched applicants was 14.71, which was higher than other competitive specialties, including orthopedic surgery and otolaryngology (11.5 and 10.4, respectively). Dermatology applicants who did not match in 2018 reported a mean of 8.6 abstracts, presentations, and publications, which was on par with successful applicants in many other specialties.¹ In 2011, Stratman and Ness² found that publishing manuscripts and listing research experience were factors strongly associated with matching into dermatology for reapplicants. These trends in reported research have added pressure for applicants to increase their publications.

Given that many students do not choose a career in dermatology until later in medical school, some students choose to take a gap year between their third and fourth years of medical school to pursue a research fellowship (RF) and produce publications, in theory to increase the chances of matching in dermatology. A survey of dermatology applicants conducted by Costello et al³ in 2021 found that, of the students who completed a gap year (n=90; 31.25%), 78.7% (n=71) of them completed an RF, and those who completed RFs were more likely to match at top dermatology residency programs (P<.01). The authors also reported that there was no significant difference in overall match rates between gap-year and non–gap-year applicants.³ Another survey of 328 medical students found that the most common reason students take years off for research during medical school is to increase competitiveness for residency application.⁴ Although it is clear that students completing an RF often find success in the match, there are limited published data on how those involved in selecting dermatology residents view this additional year. We surveyed faculty members participating in the resident selection process to assess their viewpoints on how RFs factored into an applicant’s odds of matching into dermatology residency and performance as a resident.

Materials and Methods

An institutional review board application was submitted through the Geisinger Health System (Danville, Pennsylvania), and an exemption to complete the survey was granted. The survey consisted of 16 questions via REDCap electronic data capture and was sent to a listserve of dermatology program directors who were asked to distribute the survey to program chairs and faculty members within their department. Survey questions evaluated the participants’ involvement in medical student advising and the residency selection process. Questions relating to the respondents’ opinions were based on a 5-point Likert scale on level of agreement (1=strongly agree; 5=strongly disagree) or importance (1=a great deal; 5=not at all). All responses were collected anonymously. Data points were compiled and analyzed using REDCap. Statistical analysis via χ² tests were conducted when appropriate.

Results

The survey was sent to 142 individuals and distributed to faculty members within those departments between August 16, 2019, and September 24, 2019. The survey elicited a total of 110 respondents. Demographic information is shown in eTable 1. Of these respondents, 35.5% were program directors, 23.6% were program chairs, 3.6% were both program director and program chair, and 37.3% were core faculty members. Although respondents’ roles were varied, 96.4% indicated that they were involved in both advising medical students and in selecting residents.

None of the respondents indicated that they always recommend that students complete an RF, and only 4.5% indicated that they usually recommend it; 40% of respondents rarely or never recommend an RF, while 55.5% sometimes recommend it. Although there was a variety of responses to how frequently faculty members recommend an RF, almost all respondents (98.2%) agreed that the reason medical students pursued an RF prior to residency application was to increase the competitiveness of their residency application. However, 20% of respondents believed that students in this cohort were seeking to gain a deeper understanding of the specialty, and 27.3% thought that this cohort had genuine interest in research. Interestingly, despite the medical students’ intentions of choosing an RF, most respondents (67.3%) agreed or strongly agreed that the publications produced by fellows make an impact on the dermatologic scientific community.

Although some respondents indicated that completion of an RF positively impacts resident performance with regard to patient care, most indicated that the impact was a little (26.4%) or not at all (50%). Additionally, a minority of respondents (11.8%) believed that RFs positively impact resident performance on in-service and board examinations at least a moderate amount, with 62.7% indicating no positive impact at all. Only 12.7% of participants agreed or strongly agreed that completion of an RF led to increased applicant involvement in research throughout their career, and most (73.6%) believed there were downsides to completing an RF. Finally, only 20% agreed or strongly agreed that students who completed an RF were more dedicated to the field of dermatology (eTable 2).

Further evaluation of the data indicated that the perceived utility of RFs did not affect respondents’ recommendation on whether to pursue an RF or not. For example, of the 4.5% of respondents who indicated that they always or usually recommended RFs, only 1 respondent believed that students who completed an RF were more dedicated to the field of dermatology than those who did not. Although 55.5% of respondents answered that they sometimes recommended completion of an RF, less than a quarter of this group believed that students who completed an RF were more likely to be heavily involved in research throughout their career (P=.99).

Overall, 11.8% of respondents indicated that completion of a dermatology RF influenced the evaluation of an applicant a great deal or a lot, while 53.6% of respondents indicated a little or no influence at all. Most respondents (62.8%) agreed or strongly agreed that completion of an RF can compensate for flaws in a residency application. Furthermore, when asked if completion of an RF could set 2 otherwise equivocal applicants apart from one another, 46.4% of respondents agreed or strongly agreed with the statement, while only 17.3% disagreed or strongly disagreed (eTable 2).

Comment

This study characterized how completion of an RF is viewed by those involved in advising medical students and selecting dermatology residents. The growing pressure for applicants to increase the number of publications combined with the competitiveness of applying for a dermatology residency position has led to increased participation in RFs. However, studies have found that students who completed an RF often did so despite a lack of interest.⁴ Nonetheless, little is known about how this is perceived by those involved in choosing residents.

We found that few respondents always or usually advised applicants to complete an RF, but the majority sometimes recommended them, demonstrating the complexity of this issue. Completion of an RF impacted 11.8% of respondents’ overall opinion of an applicant a lot or a great deal, while most respondents (53.6%) were influenced a little or not at all. However, 46.4% of respondents indicated that completion of a dermatology RF would set apart 2 applicants of otherwise equal standing, and 62.8% agreed or strongly agreed that completion of an RF would compensate for flaws in an application. These responses align with the findings of a study conducted by Kaffenberger et al,⁵ who surveyed members of the Association of Professors of Dermatology and found that 74.5% (73/98) of mentors almost always or sometimes recommended a research gap year for reasons that included low grades, low USMLE Step scores, and little research. These data suggest that completion of an RF can give a competitive advantage to applicants despite most advisors acknowledging that these applicants are not likely to be involved in research throughout their careers, perform better on standardized examinations, or provide better patient care.

Given the complexity of this issue, respondents may not have been able to accurately answer the question about how much an RF influenced their overall opinion of an applicant because of subconscious bias. Furthermore, respondents likely tailored their recommendations to complete an RF based on individual applicant strengths and weaknesses, and the specific reasons why one may recommend an RF need to be further investigated.

Although there may be other perceived advantages to RFs that were not captured by our survey, completion of a dermatology RF is not without disadvantages. Fellowships often are unfunded and offered in cities with high costs of living. Additionally, students are forced to delay graduation from medical school by a year at minimum and continue to accrue interest on medical school loans during this time. The financial burdens of completing an RF may exclude students of lower socioeconomic status and contribute to a decrease in diversity within the field. Dermatology has been found to be the second least diverse specialty, behind orthopedics.⁶ Soliman et al⁷ found that racial minorities and low-income students were more likely to cite socioeconomic barriers as factors involved in their decision not to pursue a career in dermatology. This notion was supported by Rinderknecht et al,⁸ who found that Black and Latinx dermatology applicants were more likely to come from disadvantaged backgrounds, and Black applicants were more likely to indicate financial concerns as their primary reason for not pursuing an RF. The impact of accumulated student debt and decreased access should be carefully weighed against the potential benefits of an RF. However, as the USMLE transitions their Step 1 score reporting from numerical to a pass/fail system, it also is possible that dermatology programs will place more emphasis on research productivity when evaluating applications for residency. Overall, the decision to recommend an RF represents an extremely complex topic, as indicated by the results of this study.

Limitations—Our survey-based study is limited by response rate and response bias. Despite the large number of responses, the overall response rate cannot be determined because it is unknown how many total faculty members actually received the survey. Moreover, data collected from current dermatology residents who have completed RFs vs those who have not as they pertain to resident performance and preparedness for the rigors of a dermatology residency would be useful.

Dermatology residency positions continue to be highly coveted among applicants in the match. In 2019, dermatology proved to be the most competitive specialty, with 36.3% of US medical school seniors and independent applicants going unmatched.¹ Prior to the transition to a pass/fail system, the mean US Medical Licensing Examination (USMLE) Step 1 score for matched applicants increased from 247 in 2014 to 251 in 2019. The growing number of scholarly activities reported by applicants has contributed to the competitiveness of the specialty. In 2018, the mean number of abstracts, presentations, and publications reported by matched applicants was 14.71, which was higher than other competitive specialties, including orthopedic surgery and otolaryngology (11.5 and 10.4, respectively). Dermatology applicants who did not match in 2018 reported a mean of 8.6 abstracts, presentations, and publications, which was on par with successful applicants in many other specialties.¹ In 2011, Stratman and Ness² found that publishing manuscripts and listing research experience were factors strongly associated with matching into dermatology for reapplicants. These trends in reported research have added pressure for applicants to increase their publications.

Given that many students do not choose a career in dermatology until later in medical school, some students choose to take a gap year between their third and fourth years of medical school to pursue a research fellowship (RF) and produce publications, in theory to increase the chances of matching in dermatology. A survey of dermatology applicants conducted by Costello et al³ in 2021 found that, of the students who completed a gap year (n=90; 31.25%), 78.7% (n=71) of them completed an RF, and those who completed RFs were more likely to match at top dermatology residency programs (P<.01). The authors also reported that there was no significant difference in overall match rates between gap-year and non–gap-year applicants.³ Another survey of 328 medical students found that the most common reason students take years off for research during medical school is to increase competitiveness for residency application.⁴ Although it is clear that students completing an RF often find success in the match, there are limited published data on how those involved in selecting dermatology residents view this additional year. We surveyed faculty members participating in the resident selection process to assess their viewpoints on how RFs factored into an applicant’s odds of matching into dermatology residency and performance as a resident.

Materials and Methods

An institutional review board application was submitted through the Geisinger Health System (Danville, Pennsylvania), and an exemption to complete the survey was granted. The survey consisted of 16 questions via REDCap electronic data capture and was sent to a listserve of dermatology program directors who were asked to distribute the survey to program chairs and faculty members within their department. Survey questions evaluated the participants’ involvement in medical student advising and the residency selection process. Questions relating to the respondents’ opinions were based on a 5-point Likert scale on level of agreement (1=strongly agree; 5=strongly disagree) or importance (1=a great deal; 5=not at all). All responses were collected anonymously. Data points were compiled and analyzed using REDCap. Statistical analysis via χ² tests were conducted when appropriate.

Results

The survey was sent to 142 individuals and distributed to faculty members within those departments between August 16, 2019, and September 24, 2019. The survey elicited a total of 110 respondents. Demographic information is shown in eTable 1. Of these respondents, 35.5% were program directors, 23.6% were program chairs, 3.6% were both program director and program chair, and 37.3% were core faculty members. Although respondents’ roles were varied, 96.4% indicated that they were involved in both advising medical students and in selecting residents.

None of the respondents indicated that they always recommend that students complete an RF, and only 4.5% indicated that they usually recommend it; 40% of respondents rarely or never recommend an RF, while 55.5% sometimes recommend it. Although there was a variety of responses to how frequently faculty members recommend an RF, almost all respondents (98.2%) agreed that the reason medical students pursued an RF prior to residency application was to increase the competitiveness of their residency application. However, 20% of respondents believed that students in this cohort were seeking to gain a deeper understanding of the specialty, and 27.3% thought that this cohort had genuine interest in research. Interestingly, despite the medical students’ intentions of choosing an RF, most respondents (67.3%) agreed or strongly agreed that the publications produced by fellows make an impact on the dermatologic scientific community.

Although some respondents indicated that completion of an RF positively impacts resident performance with regard to patient care, most indicated that the impact was a little (26.4%) or not at all (50%). Additionally, a minority of respondents (11.8%) believed that RFs positively impact resident performance on in-service and board examinations at least a moderate amount, with 62.7% indicating no positive impact at all. Only 12.7% of participants agreed or strongly agreed that completion of an RF led to increased applicant involvement in research throughout their career, and most (73.6%) believed there were downsides to completing an RF. Finally, only 20% agreed or strongly agreed that students who completed an RF were more dedicated to the field of dermatology (eTable 2).

Further evaluation of the data indicated that the perceived utility of RFs did not affect respondents’ recommendation on whether to pursue an RF or not. For example, of the 4.5% of respondents who indicated that they always or usually recommended RFs, only 1 respondent believed that students who completed an RF were more dedicated to the field of dermatology than those who did not. Although 55.5% of respondents answered that they sometimes recommended completion of an RF, less than a quarter of this group believed that students who completed an RF were more likely to be heavily involved in research throughout their career (P=.99).

Overall, 11.8% of respondents indicated that completion of a dermatology RF influenced the evaluation of an applicant a great deal or a lot, while 53.6% of respondents indicated a little or no influence at all. Most respondents (62.8%) agreed or strongly agreed that completion of an RF can compensate for flaws in a residency application. Furthermore, when asked if completion of an RF could set 2 otherwise equivocal applicants apart from one another, 46.4% of respondents agreed or strongly agreed with the statement, while only 17.3% disagreed or strongly disagreed (eTable 2).

Comment

This study characterized how completion of an RF is viewed by those involved in advising medical students and selecting dermatology residents. The growing pressure for applicants to increase the number of publications combined with the competitiveness of applying for a dermatology residency position has led to increased participation in RFs. However, studies have found that students who completed an RF often did so despite a lack of interest.⁴ Nonetheless, little is known about how this is perceived by those involved in choosing residents.

We found that few respondents always or usually advised applicants to complete an RF, but the majority sometimes recommended them, demonstrating the complexity of this issue. Completion of an RF impacted 11.8% of respondents’ overall opinion of an applicant a lot or a great deal, while most respondents (53.6%) were influenced a little or not at all. However, 46.4% of respondents indicated that completion of a dermatology RF would set apart 2 applicants of otherwise equal standing, and 62.8% agreed or strongly agreed that completion of an RF would compensate for flaws in an application. These responses align with the findings of a study conducted by Kaffenberger et al,⁵ who surveyed members of the Association of Professors of Dermatology and found that 74.5% (73/98) of mentors almost always or sometimes recommended a research gap year for reasons that included low grades, low USMLE Step scores, and little research. These data suggest that completion of an RF can give a competitive advantage to applicants despite most advisors acknowledging that these applicants are not likely to be involved in research throughout their careers, perform better on standardized examinations, or provide better patient care.

Given the complexity of this issue, respondents may not have been able to accurately answer the question about how much an RF influenced their overall opinion of an applicant because of subconscious bias. Furthermore, respondents likely tailored their recommendations to complete an RF based on individual applicant strengths and weaknesses, and the specific reasons why one may recommend an RF need to be further investigated.

Although there may be other perceived advantages to RFs that were not captured by our survey, completion of a dermatology RF is not without disadvantages. Fellowships often are unfunded and offered in cities with high costs of living. Additionally, students are forced to delay graduation from medical school by a year at minimum and continue to accrue interest on medical school loans during this time. The financial burdens of completing an RF may exclude students of lower socioeconomic status and contribute to a decrease in diversity within the field. Dermatology has been found to be the second least diverse specialty, behind orthopedics.⁶ Soliman et al⁷ found that racial minorities and low-income students were more likely to cite socioeconomic barriers as factors involved in their decision not to pursue a career in dermatology. This notion was supported by Rinderknecht et al,⁸ who found that Black and Latinx dermatology applicants were more likely to come from disadvantaged backgrounds, and Black applicants were more likely to indicate financial concerns as their primary reason for not pursuing an RF. The impact of accumulated student debt and decreased access should be carefully weighed against the potential benefits of an RF. However, as the USMLE transitions their Step 1 score reporting from numerical to a pass/fail system, it also is possible that dermatology programs will place more emphasis on research productivity when evaluating applications for residency. Overall, the decision to recommend an RF represents an extremely complex topic, as indicated by the results of this study.

Limitations—Our survey-based study is limited by response rate and response bias. Despite the large number of responses, the overall response rate cannot be determined because it is unknown how many total faculty members actually received the survey. Moreover, data collected from current dermatology residents who have completed RFs vs those who have not as they pertain to resident performance and preparedness for the rigors of a dermatology residency would be useful.

Dermatology residency positions continue to be highly coveted among applicants in the match. In 2019, dermatology proved to be the most competitive specialty, with 36.3% of US medical school seniors and independent applicants going unmatched.¹ Prior to the transition to a pass/fail system, the mean US Medical Licensing Examination (USMLE) Step 1 score for matched applicants increased from 247 in 2014 to 251 in 2019. The growing number of scholarly activities reported by applicants has contributed to the competitiveness of the specialty. In 2018, the mean number of abstracts, presentations, and publications reported by matched applicants was 14.71, which was higher than other competitive specialties, including orthopedic surgery and otolaryngology (11.5 and 10.4, respectively). Dermatology applicants who did not match in 2018 reported a mean of 8.6 abstracts, presentations, and publications, which was on par with successful applicants in many other specialties.¹ In 2011, Stratman and Ness² found that publishing manuscripts and listing research experience were factors strongly associated with matching into dermatology for reapplicants. These trends in reported research have added pressure for applicants to increase their publications.

Given that many students do not choose a career in dermatology until later in medical school, some students choose to take a gap year between their third and fourth years of medical school to pursue a research fellowship (RF) and produce publications, in theory to increase the chances of matching in dermatology. A survey of dermatology applicants conducted by Costello et al³ in 2021 found that, of the students who completed a gap year (n=90; 31.25%), 78.7% (n=71) of them completed an RF, and those who completed RFs were more likely to match at top dermatology residency programs (P<.01). The authors also reported that there was no significant difference in overall match rates between gap-year and non–gap-year applicants.³ Another survey of 328 medical students found that the most common reason students take years off for research during medical school is to increase competitiveness for residency application.⁴ Although it is clear that students completing an RF often find success in the match, there are limited published data on how those involved in selecting dermatology residents view this additional year. We surveyed faculty members participating in the resident selection process to assess their viewpoints on how RFs factored into an applicant’s odds of matching into dermatology residency and performance as a resident.

Materials and Methods

An institutional review board application was submitted through the Geisinger Health System (Danville, Pennsylvania), and an exemption to complete the survey was granted. The survey consisted of 16 questions via REDCap electronic data capture and was sent to a listserve of dermatology program directors who were asked to distribute the survey to program chairs and faculty members within their department. Survey questions evaluated the participants’ involvement in medical student advising and the residency selection process. Questions relating to the respondents’ opinions were based on a 5-point Likert scale on level of agreement (1=strongly agree; 5=strongly disagree) or importance (1=a great deal; 5=not at all). All responses were collected anonymously. Data points were compiled and analyzed using REDCap. Statistical analysis via χ² tests were conducted when appropriate.

Results

The survey was sent to 142 individuals and distributed to faculty members within those departments between August 16, 2019, and September 24, 2019. The survey elicited a total of 110 respondents. Demographic information is shown in eTable 1. Of these respondents, 35.5% were program directors, 23.6% were program chairs, 3.6% were both program director and program chair, and 37.3% were core faculty members. Although respondents’ roles were varied, 96.4% indicated that they were involved in both advising medical students and in selecting residents.

None of the respondents indicated that they always recommend that students complete an RF, and only 4.5% indicated that they usually recommend it; 40% of respondents rarely or never recommend an RF, while 55.5% sometimes recommend it. Although there was a variety of responses to how frequently faculty members recommend an RF, almost all respondents (98.2%) agreed that the reason medical students pursued an RF prior to residency application was to increase the competitiveness of their residency application. However, 20% of respondents believed that students in this cohort were seeking to gain a deeper understanding of the specialty, and 27.3% thought that this cohort had genuine interest in research. Interestingly, despite the medical students’ intentions of choosing an RF, most respondents (67.3%) agreed or strongly agreed that the publications produced by fellows make an impact on the dermatologic scientific community.

Although some respondents indicated that completion of an RF positively impacts resident performance with regard to patient care, most indicated that the impact was a little (26.4%) or not at all (50%). Additionally, a minority of respondents (11.8%) believed that RFs positively impact resident performance on in-service and board examinations at least a moderate amount, with 62.7% indicating no positive impact at all. Only 12.7% of participants agreed or strongly agreed that completion of an RF led to increased applicant involvement in research throughout their career, and most (73.6%) believed there were downsides to completing an RF. Finally, only 20% agreed or strongly agreed that students who completed an RF were more dedicated to the field of dermatology (eTable 2).

Further evaluation of the data indicated that the perceived utility of RFs did not affect respondents’ recommendation on whether to pursue an RF or not. For example, of the 4.5% of respondents who indicated that they always or usually recommended RFs, only 1 respondent believed that students who completed an RF were more dedicated to the field of dermatology than those who did not. Although 55.5% of respondents answered that they sometimes recommended completion of an RF, less than a quarter of this group believed that students who completed an RF were more likely to be heavily involved in research throughout their career (P=.99).

Overall, 11.8% of respondents indicated that completion of a dermatology RF influenced the evaluation of an applicant a great deal or a lot, while 53.6% of respondents indicated a little or no influence at all. Most respondents (62.8%) agreed or strongly agreed that completion of an RF can compensate for flaws in a residency application. Furthermore, when asked if completion of an RF could set 2 otherwise equivocal applicants apart from one another, 46.4% of respondents agreed or strongly agreed with the statement, while only 17.3% disagreed or strongly disagreed (eTable 2).

Comment

This study characterized how completion of an RF is viewed by those involved in advising medical students and selecting dermatology residents. The growing pressure for applicants to increase the number of publications combined with the competitiveness of applying for a dermatology residency position has led to increased participation in RFs. However, studies have found that students who completed an RF often did so despite a lack of interest.⁴ Nonetheless, little is known about how this is perceived by those involved in choosing residents.

We found that few respondents always or usually advised applicants to complete an RF, but the majority sometimes recommended them, demonstrating the complexity of this issue. Completion of an RF impacted 11.8% of respondents’ overall opinion of an applicant a lot or a great deal, while most respondents (53.6%) were influenced a little or not at all. However, 46.4% of respondents indicated that completion of a dermatology RF would set apart 2 applicants of otherwise equal standing, and 62.8% agreed or strongly agreed that completion of an RF would compensate for flaws in an application. These responses align with the findings of a study conducted by Kaffenberger et al,⁵ who surveyed members of the Association of Professors of Dermatology and found that 74.5% (73/98) of mentors almost always or sometimes recommended a research gap year for reasons that included low grades, low USMLE Step scores, and little research. These data suggest that completion of an RF can give a competitive advantage to applicants despite most advisors acknowledging that these applicants are not likely to be involved in research throughout their careers, perform better on standardized examinations, or provide better patient care.

Given the complexity of this issue, respondents may not have been able to accurately answer the question about how much an RF influenced their overall opinion of an applicant because of subconscious bias. Furthermore, respondents likely tailored their recommendations to complete an RF based on individual applicant strengths and weaknesses, and the specific reasons why one may recommend an RF need to be further investigated.

Although there may be other perceived advantages to RFs that were not captured by our survey, completion of a dermatology RF is not without disadvantages. Fellowships often are unfunded and offered in cities with high costs of living. Additionally, students are forced to delay graduation from medical school by a year at minimum and continue to accrue interest on medical school loans during this time. The financial burdens of completing an RF may exclude students of lower socioeconomic status and contribute to a decrease in diversity within the field. Dermatology has been found to be the second least diverse specialty, behind orthopedics.⁶ Soliman et al⁷ found that racial minorities and low-income students were more likely to cite socioeconomic barriers as factors involved in their decision not to pursue a career in dermatology. This notion was supported by Rinderknecht et al,⁸ who found that Black and Latinx dermatology applicants were more likely to come from disadvantaged backgrounds, and Black applicants were more likely to indicate financial concerns as their primary reason for not pursuing an RF. The impact of accumulated student debt and decreased access should be carefully weighed against the potential benefits of an RF. However, as the USMLE transitions their Step 1 score reporting from numerical to a pass/fail system, it also is possible that dermatology programs will place more emphasis on research productivity when evaluating applications for residency. Overall, the decision to recommend an RF represents an extremely complex topic, as indicated by the results of this study.

Limitations—Our survey-based study is limited by response rate and response bias. Despite the large number of responses, the overall response rate cannot be determined because it is unknown how many total faculty members actually received the survey. Moreover, data collected from current dermatology residents who have completed RFs vs those who have not as they pertain to resident performance and preparedness for the rigors of a dermatology residency would be useful.

Melasma is a complex, long-lasting, acquired dermatologic pigmentation disorder resulting in grey-brown patches that last for more than 3 months. Sun-exposed areas including the nose, cheeks, forehead, and forearms are most likely to be affected.¹ In Southeast Asia, 0.25% to 4% of the population affected by melasma is aged 30 to 40 years.² In particular, melasma is a concern among pregnant women due to increased levels of melanocyte-stimulating hormones (MSHs) and is impacted by genetics, hormonal influence, and exposure to UV light.^3,4 In Pakistan, approximately 46% of women are affected by melasma during pregnancy.^2,5 Although few studies have focused on the clinical approaches to melasma in darker skin types, it continues to disproportionately affect the skin of color population.⁴

The areas of hyperpigmentation seen in melasma exhibit increased deposition of melanin in the epidermis and dermis, but melanocytes are not elevated. However, in areas of hyperpigmentation, the melanocytes are larger and more dendritic and demonstrate an increased level of melanogenesis.⁶ During pregnancy, especially in the third trimester, elevated levels of estrogen, progesterone, and MSH often are found in association with melasma.⁷ Tyrosinase (TYR) activity increases and cellular proliferation is reduced after treatment of melanocytes in culture with β-estradiol.⁸ Sex steroids increase transcription of genes encoding melanogenic enzymes in normal human melanocytes, especially TYR.⁹ These results are consistent with the notable increases in melanin synthesis and TYR activity reported for normal human melanocytes under similar conditions in culture.¹⁰ Because melanocytes contain both cytosolic and nuclear estrogen receptors, melanocytes in patients with melasma may be inherently more sensitive to the stimulatory effects of estrogens and possibly other steroid hormones.¹¹

The current treatment options for melasma have varying levels of success and include topical depigmenting agents such as hydroquinone, tretinoin, azelaic acid, kojic acid, and corticosteroids; dermabrasion; and chemical peels.^12-14 Chemical peels with glycolic acid, salicylic acid, lactic acid, trichloroacetic acid, and phenol, as well as laser therapy, are reliable management options.^13,14 Traditionally, melasma has been treated with a combination of modalities along with photoprotection and trigger avoidance.¹²

The efficacy and safety of the available therapies for melasma are still controversial and require further exploration. In recent years, off-label tranexamic acid (TA) has emerged as a potential therapy for melasma. Although the mechanism of action remains unclear, TA may inhibit melanin synthesis by blocking the interaction between melanocytes and keratinocytes.¹⁵ Tranexamic acid also may reverse the abnormal dermal changes associated with melasma by inhibiting melanogenesis and angiogenesis.¹⁶

Although various therapeutic options exist for melasma, the search for a reliable option in patients with darker skin types continues.¹³ We sought to evaluate the efficacy of TA solution 5% in reducing the severity of melasma in South Asian patients, thereby improving patient outcomes and maximizing patient satisfaction. Topical TA is inexpensive and readily accessible and does not cause systemic side effects. These qualities make it a promising treatment compared to traditional therapies.

Methods

We conducted a randomized controlled trial at Rawalpindi Medical Institute (Punjab, Pakistan). The researchers obtained informed consent for all enrolled patients. Cases were sampled from the original patient population seen at the office using nonprobability consecutive sampling. The sample size was calculated with a 95% CI, margin of error of 9%, and expected percentage of efficacy of 86.1% by using TA solution 5%. South Asian male and female patients aged 20 to 45 years with melasma were included in the analysis. Patients were excluded if they were already taking TA, oral contraceptive pills, or photosensitizing drugs (eg, nonsteroidal anti-inflammatory drugs, tetracyclines, phenytoin, carbamazepine); were pregnant; had chronic kidney disease (creatinine >2.0 mg/dL); had cardiac abnormalities (abnormal electrocardiogram); had hematologic disorders (international normalized ratio >2); or had received another melasma treatment within the last 3 to 6 months.

All enrolled patients underwent a detailed history and physical examination. Patient demographics were subsequently noted, including age, sex, history of diabetes mellitus or hypertension, and duration of melasma. The melasma area and severity index (MASI) score of each patient was calculated at baseline, and a corresponding photograph was taken.

The topical solution was prepared with 5 g of TA dissolved in 10 cc of ethanol at 96 °F, 10 cc of 1,3-butanediol, and distilled water up to 100 cc. The TA solution was applied to the affected areas once daily by the patient for 12 weeks. Each application covered the affected areas completely. Patients were instructed to apply sunscreen with sun protection factor 60 to those same areas for UV protection after 15 minutes of TA application. Biweekly follow-ups were scheduled during the trial, and the MASI score was recorded at these visits. If the mean MASI score was reduced by half after 12 weeks of treatment, then the treatment was considered efficacious with a 95% CI.

The percentage reduction from baseline was calculated as follows: percentage reduction=(baseline score– follow-up score)/baseline score×100.

Statistical Analysis—Data were analyzed in SPSS Statistics 25 (IBM). The quantitative variables of age, duration of melasma, and body mass index were presented as mean (SD). Qualitative variables such as sex, history of diabetes mellitus or hypertension, site of melasma, and efficacy were presented as frequencies and percentages. Mean MASI scores at baseline and 12 weeks posttreatment were compared using a paired t test (P≤.05). Data were stratified for age, sex, history of diabetes mellitus or hypertension, site of melasma, and duration of melasma, and a χ² test was applied to compare efficacy in stratified groups (P≤.05).

Results

Sixty patients were enrolled in the study. Of them, 17 (28.33%) were male, and 43 (71.67%) were female (2:5 ratio). They ranged in age from 20 to 45 years (mean [SD], 31.93 [6.26] years). Thirty-seven patients (61.67%) were aged 31 to 45 years of age (Table 1). The mean (SD) duration of disease was 10.18 (2.10) months. The response to TA was recorded based on patient distribution according to the site of melasma as well as history of diabetes mellitus and hypertension.

Topical TA was found to be efficacious for melasma in 50 (83.33%) patients. The mean (SD) baseline and week 12 MASI scores were 23.15 (5.02) and 12.71 (4.10)(P<.0001), respectively (Table 2). The stratification of efficacy with respect to age, sex, duration of melasma, site of melasma, and history of diabetes mellitus or hypertension is shown in the eTable. The site of melasma was significant with respect to stratification of efficacy. On the forehead, TA was found to be efficacious in 11 patients and nonefficacious in 0 patients (P=.036). In the malar region, it was efficacious in 16 patients and nonefficacious in 1 patient (P=.036). Finally, on the chin, it was efficacious in 23 patients and nonefficacious in 9 patients (P=.036).

Comment

Melasma Presentation and Development—Melasma is a chronic skin condition that more often affects patients with darker skin types. This condition is characterized by hyperpigmentation of skin that is directly exposed to the sun, such as the cheek, nose, forehead, and above the upper lip.¹⁷ Although the mechanism behind how melasma develops is unknown, one theory suggests that UV light can lead to increased plasmin in keratinocytes.¹⁸ This increased plasmin will thereby increase the arachidonic acid and α-MSH, leading to the observed uneven hyperpigmentation that is notable in melasma. Melasma is common in patients using oral contraceptives or expired cosmetic drugs; in those who are pregnant; and in those with liver dysfunction.¹⁸ Melasma has a negative impact on patients’ quality of life because of substantial psychological and social distress. Thus, finding an accessible treatment is imperative.¹⁹

Melasma Management—The most common treatments for melasma have been topical bleaching agents and photoprotection. Combination therapy options include chemical peels, dermabrasion, and laser treatments, though they present with limited efficacy.^17,20 Because melasma focuses on pigmentation correction, topical treatments work to disturb melanocyte pigment production at the enzymatic level.²¹ Tyrosinase is rate limiting in melanin production, as it converts L-tyrosinase to L-3,4-dihydroxyphenylalanine, using copper to interact with L-3,4-dihydroxyphenylalanine as a cofactor in the active site.²² Therefore, tyrosine is a major target for many drugs that have been developed for melasma to decrease melaninization.²¹

Recently, research has focused on the effects of topical, intradermal, and oral TA for melasma.¹⁷ Tranexamic acid most commonly has been used in medicine as a fibrinolytic agent because of its antiplasmin properties. It has been hypothesized that TA can inhibit the release of paracrine melanogenic factors that normally act to stimulate melanocytes.¹⁷ Although studies have supported the safety and efficacy of TA, there remains a lack of clinical studies that are sufficiently powered. No definitive consensus on the use of TA for melasma currently exists, which indicates the need for large-scale, randomized, controlled trials.²³

One trial (N=25) found that TA solution 5% achieved efficacy (>50% reduction in MASI score from baseline) in 86.1% of patients with melasma.²⁴ In another study (N=18), topical TA 5% achieved efficacy (>50% reduction in MASI score) in 86% of patients with melasma.²⁵

Melasma Comorbidities—To determine if certain comorbidities, such as diabetes mellitus or hypertension, influenced the progression of melasma, we stratified the efficacy results for patients with these 2 comorbidities, which showed no significant difference (P=.794 and P=.101, respectively). Thus, the relatively higher prevalence of diabetes mellitus (16 patients) and hypertension (11 patients) did not contribute to the efficacy of TA in lowering MASI scores over the 12-week period, which supports the findings of Doolan and Gupta,²⁶ who investigated the endocrinologic conditions associated with melasma and found no such association with diabetes mellitus or hypertension.

TA Formulations for Melasma—The efficacy of topical TA has been explored in several studies. Six studies with sample sizes of 13 to 50 patients each showed statistically significant differences in MASI scores between baseline and following TA treatment (P<.001).^27-32 Several formulations and regimens were utilized, including TA cream 3% for 12 weeks, TA gel 5% for 12 weeks, TA solution 3% for 12 weeks, TA liposome 5% for 12 weeks, and TA solution 2% for 12 weeks.¹⁸ Additionally, these studies found TA to be effective in limiting dyschromia and decreasing MASI scores. There were no statistically significant differences between formulations and method of application. Topical TA has been found to be just as effective as other treatments for melasma, including intradermal TA injections, topical hydroquinone, and a combination of topical hydroquinone and dexamethasone.¹⁸

Further study of the efficacy of intradermal TA is necessary because many human trials have lacked statistical significance or a control group. Lee et al³² conducted a trial of 100 female patients who received weekly intradermal TA microinjections for 12 weeks. After 8 and 12 weeks, MASI scores decreased significantly (P<.01).³² Similarly, Badran et al³³ observed 60 female patients in 3 trial groups: group A received TA (4 mg/mL) intradermal injections every 2 weeks, group B received TA (10 mg/mL) intradermal injections every 2 weeks, and group C received TA cream 10% twice daily. Although all groups showed improvement in MASI, group B, which had the highest intradermal TA concentration, exhibited the most improvement. Thus, it was determined that intradermal application led to better results, but the cream was still effective.³³

Saki et al³⁴ conducted a randomized, split-face trial of 37 patients comparing the efficacy of intradermal TA and topical hydroquinone. Each group was treated with either monthly intradermal TA injections or nightly hydroquinone for 3 months. After 4 weeks of treatment, TA initially had a greater improvement. However, after 20 weeks, the overall changes were not significant between the 2 groups.³⁴ Pazyar et al³⁵ conducted a randomized, split-face trial of 49 patients comparing the efficacy of intradermal TA and hydroquinone cream. After 24 weeks of biweekly TA injections or twice-daily hydroquinone, there were no statistically significant differences in the decreased MASI scores between treatments.³⁵ Additional large, double-blind, controlled trials are needed to thoroughly assess the role of intradermal TA in comparison to its treatment counterpart of hydroquinone.

Ebrahimi and Naeini²⁹ conducted a 12-week, double-blind, split-phase trial of 50 Iranian melasma patients, which showed that 27.3% of patients rated the improvement in melasma as excellent, 42.4% as good, and 30.3% as fair after using TA solution 3%. Wu et al³⁶ also showed a total melasma improvement rate of 80.9% in 256 patients with long-term oral use of TA. In a study by Kim et al³¹ (N=245), the mean MASI score considerably decreased after topical TA use, with a total response rate of 95.6%. In another study, Atefi et al³⁷ presented significantly increased levels of satisfaction in patients treated with topical TA 5% vs hydroquinone (P=.015).

Melasma in Patients With Darker Skin Types—Special attention must be given to choosing the appropriate medication in melasma patients with darker skin types, as there is an increased risk for postinflammatory hyperpigmentation. Currently, few randomized controlled trials exist that fulfill the criteria of evaluating pharmacologic options for patients with melasma, and even fewer studies solely focus on patients with darker skin types.³⁸ In addition to treatment advances, patients must be educated on the need to avoid sun exposure when possible or to use photoprotection, especially in the South Asian region, where these practices rarely are taught. Our study provided a unique analysis regarding the efficacy of TA solution 5% for the treatment of melasma in patients of South Asian descent. Clinicians can use these findings as a foundation for treating all patients with melasma but particularly those with darker skin types.

Study Limitations—Our study consisted of 60 patients; although our study had more patients than similar trials, larger studies are needed. Additionally, other variables were excluded from our analysis, such as comorbidities beyond diabetes mellitus and hypertension.

Conclusion

This study contributes to the growing field of melasma therapeutics by evaluating the efficacy of using TA solution 5% for the treatment of melasma in South Asian patients with darker skin types. Clinicians may use our study to broaden their treatment options for a common condition while also addressing the lack of clinical options for patients with darker skin types. Further studies investigating the effectiveness of TA in large clinical trials in humans are warranted to understand the efficacy and the risk for any complications.

Melasma is a complex, long-lasting, acquired dermatologic pigmentation disorder resulting in grey-brown patches that last for more than 3 months. Sun-exposed areas including the nose, cheeks, forehead, and forearms are most likely to be affected.¹ In Southeast Asia, 0.25% to 4% of the population affected by melasma is aged 30 to 40 years.² In particular, melasma is a concern among pregnant women due to increased levels of melanocyte-stimulating hormones (MSHs) and is impacted by genetics, hormonal influence, and exposure to UV light.^3,4 In Pakistan, approximately 46% of women are affected by melasma during pregnancy.^2,5 Although few studies have focused on the clinical approaches to melasma in darker skin types, it continues to disproportionately affect the skin of color population.⁴

The areas of hyperpigmentation seen in melasma exhibit increased deposition of melanin in the epidermis and dermis, but melanocytes are not elevated. However, in areas of hyperpigmentation, the melanocytes are larger and more dendritic and demonstrate an increased level of melanogenesis.⁶ During pregnancy, especially in the third trimester, elevated levels of estrogen, progesterone, and MSH often are found in association with melasma.⁷ Tyrosinase (TYR) activity increases and cellular proliferation is reduced after treatment of melanocytes in culture with β-estradiol.⁸ Sex steroids increase transcription of genes encoding melanogenic enzymes in normal human melanocytes, especially TYR.⁹ These results are consistent with the notable increases in melanin synthesis and TYR activity reported for normal human melanocytes under similar conditions in culture.¹⁰ Because melanocytes contain both cytosolic and nuclear estrogen receptors, melanocytes in patients with melasma may be inherently more sensitive to the stimulatory effects of estrogens and possibly other steroid hormones.¹¹

The current treatment options for melasma have varying levels of success and include topical depigmenting agents such as hydroquinone, tretinoin, azelaic acid, kojic acid, and corticosteroids; dermabrasion; and chemical peels.^12-14 Chemical peels with glycolic acid, salicylic acid, lactic acid, trichloroacetic acid, and phenol, as well as laser therapy, are reliable management options.^13,14 Traditionally, melasma has been treated with a combination of modalities along with photoprotection and trigger avoidance.¹²

The efficacy and safety of the available therapies for melasma are still controversial and require further exploration. In recent years, off-label tranexamic acid (TA) has emerged as a potential therapy for melasma. Although the mechanism of action remains unclear, TA may inhibit melanin synthesis by blocking the interaction between melanocytes and keratinocytes.¹⁵ Tranexamic acid also may reverse the abnormal dermal changes associated with melasma by inhibiting melanogenesis and angiogenesis.¹⁶

Although various therapeutic options exist for melasma, the search for a reliable option in patients with darker skin types continues.¹³ We sought to evaluate the efficacy of TA solution 5% in reducing the severity of melasma in South Asian patients, thereby improving patient outcomes and maximizing patient satisfaction. Topical TA is inexpensive and readily accessible and does not cause systemic side effects. These qualities make it a promising treatment compared to traditional therapies.

Methods

We conducted a randomized controlled trial at Rawalpindi Medical Institute (Punjab, Pakistan). The researchers obtained informed consent for all enrolled patients. Cases were sampled from the original patient population seen at the office using nonprobability consecutive sampling. The sample size was calculated with a 95% CI, margin of error of 9%, and expected percentage of efficacy of 86.1% by using TA solution 5%. South Asian male and female patients aged 20 to 45 years with melasma were included in the analysis. Patients were excluded if they were already taking TA, oral contraceptive pills, or photosensitizing drugs (eg, nonsteroidal anti-inflammatory drugs, tetracyclines, phenytoin, carbamazepine); were pregnant; had chronic kidney disease (creatinine >2.0 mg/dL); had cardiac abnormalities (abnormal electrocardiogram); had hematologic disorders (international normalized ratio >2); or had received another melasma treatment within the last 3 to 6 months.

All enrolled patients underwent a detailed history and physical examination. Patient demographics were subsequently noted, including age, sex, history of diabetes mellitus or hypertension, and duration of melasma. The melasma area and severity index (MASI) score of each patient was calculated at baseline, and a corresponding photograph was taken.

The topical solution was prepared with 5 g of TA dissolved in 10 cc of ethanol at 96 °F, 10 cc of 1,3-butanediol, and distilled water up to 100 cc. The TA solution was applied to the affected areas once daily by the patient for 12 weeks. Each application covered the affected areas completely. Patients were instructed to apply sunscreen with sun protection factor 60 to those same areas for UV protection after 15 minutes of TA application. Biweekly follow-ups were scheduled during the trial, and the MASI score was recorded at these visits. If the mean MASI score was reduced by half after 12 weeks of treatment, then the treatment was considered efficacious with a 95% CI.

The percentage reduction from baseline was calculated as follows: percentage reduction=(baseline score– follow-up score)/baseline score×100.

Statistical Analysis—Data were analyzed in SPSS Statistics 25 (IBM). The quantitative variables of age, duration of melasma, and body mass index were presented as mean (SD). Qualitative variables such as sex, history of diabetes mellitus or hypertension, site of melasma, and efficacy were presented as frequencies and percentages. Mean MASI scores at baseline and 12 weeks posttreatment were compared using a paired t test (P≤.05). Data were stratified for age, sex, history of diabetes mellitus or hypertension, site of melasma, and duration of melasma, and a χ² test was applied to compare efficacy in stratified groups (P≤.05).

Results

Sixty patients were enrolled in the study. Of them, 17 (28.33%) were male, and 43 (71.67%) were female (2:5 ratio). They ranged in age from 20 to 45 years (mean [SD], 31.93 [6.26] years). Thirty-seven patients (61.67%) were aged 31 to 45 years of age (Table 1). The mean (SD) duration of disease was 10.18 (2.10) months. The response to TA was recorded based on patient distribution according to the site of melasma as well as history of diabetes mellitus and hypertension.

Topical TA was found to be efficacious for melasma in 50 (83.33%) patients. The mean (SD) baseline and week 12 MASI scores were 23.15 (5.02) and 12.71 (4.10)(P<.0001), respectively (Table 2). The stratification of efficacy with respect to age, sex, duration of melasma, site of melasma, and history of diabetes mellitus or hypertension is shown in the eTable. The site of melasma was significant with respect to stratification of efficacy. On the forehead, TA was found to be efficacious in 11 patients and nonefficacious in 0 patients (P=.036). In the malar region, it was efficacious in 16 patients and nonefficacious in 1 patient (P=.036). Finally, on the chin, it was efficacious in 23 patients and nonefficacious in 9 patients (P=.036).

Comment

Melasma Presentation and Development—Melasma is a chronic skin condition that more often affects patients with darker skin types. This condition is characterized by hyperpigmentation of skin that is directly exposed to the sun, such as the cheek, nose, forehead, and above the upper lip.¹⁷ Although the mechanism behind how melasma develops is unknown, one theory suggests that UV light can lead to increased plasmin in keratinocytes.¹⁸ This increased plasmin will thereby increase the arachidonic acid and α-MSH, leading to the observed uneven hyperpigmentation that is notable in melasma. Melasma is common in patients using oral contraceptives or expired cosmetic drugs; in those who are pregnant; and in those with liver dysfunction.¹⁸ Melasma has a negative impact on patients’ quality of life because of substantial psychological and social distress. Thus, finding an accessible treatment is imperative.¹⁹

Melasma Management—The most common treatments for melasma have been topical bleaching agents and photoprotection. Combination therapy options include chemical peels, dermabrasion, and laser treatments, though they present with limited efficacy.^17,20 Because melasma focuses on pigmentation correction, topical treatments work to disturb melanocyte pigment production at the enzymatic level.²¹ Tyrosinase is rate limiting in melanin production, as it converts L-tyrosinase to L-3,4-dihydroxyphenylalanine, using copper to interact with L-3,4-dihydroxyphenylalanine as a cofactor in the active site.²² Therefore, tyrosine is a major target for many drugs that have been developed for melasma to decrease melaninization.²¹

Recently, research has focused on the effects of topical, intradermal, and oral TA for melasma.¹⁷ Tranexamic acid most commonly has been used in medicine as a fibrinolytic agent because of its antiplasmin properties. It has been hypothesized that TA can inhibit the release of paracrine melanogenic factors that normally act to stimulate melanocytes.¹⁷ Although studies have supported the safety and efficacy of TA, there remains a lack of clinical studies that are sufficiently powered. No definitive consensus on the use of TA for melasma currently exists, which indicates the need for large-scale, randomized, controlled trials.²³

One trial (N=25) found that TA solution 5% achieved efficacy (>50% reduction in MASI score from baseline) in 86.1% of patients with melasma.²⁴ In another study (N=18), topical TA 5% achieved efficacy (>50% reduction in MASI score) in 86% of patients with melasma.²⁵

Melasma Comorbidities—To determine if certain comorbidities, such as diabetes mellitus or hypertension, influenced the progression of melasma, we stratified the efficacy results for patients with these 2 comorbidities, which showed no significant difference (P=.794 and P=.101, respectively). Thus, the relatively higher prevalence of diabetes mellitus (16 patients) and hypertension (11 patients) did not contribute to the efficacy of TA in lowering MASI scores over the 12-week period, which supports the findings of Doolan and Gupta,²⁶ who investigated the endocrinologic conditions associated with melasma and found no such association with diabetes mellitus or hypertension.

TA Formulations for Melasma—The efficacy of topical TA has been explored in several studies. Six studies with sample sizes of 13 to 50 patients each showed statistically significant differences in MASI scores between baseline and following TA treatment (P<.001).^27-32 Several formulations and regimens were utilized, including TA cream 3% for 12 weeks, TA gel 5% for 12 weeks, TA solution 3% for 12 weeks, TA liposome 5% for 12 weeks, and TA solution 2% for 12 weeks.¹⁸ Additionally, these studies found TA to be effective in limiting dyschromia and decreasing MASI scores. There were no statistically significant differences between formulations and method of application. Topical TA has been found to be just as effective as other treatments for melasma, including intradermal TA injections, topical hydroquinone, and a combination of topical hydroquinone and dexamethasone.¹⁸

Further study of the efficacy of intradermal TA is necessary because many human trials have lacked statistical significance or a control group. Lee et al³² conducted a trial of 100 female patients who received weekly intradermal TA microinjections for 12 weeks. After 8 and 12 weeks, MASI scores decreased significantly (P<.01).³² Similarly, Badran et al³³ observed 60 female patients in 3 trial groups: group A received TA (4 mg/mL) intradermal injections every 2 weeks, group B received TA (10 mg/mL) intradermal injections every 2 weeks, and group C received TA cream 10% twice daily. Although all groups showed improvement in MASI, group B, which had the highest intradermal TA concentration, exhibited the most improvement. Thus, it was determined that intradermal application led to better results, but the cream was still effective.³³

Saki et al³⁴ conducted a randomized, split-face trial of 37 patients comparing the efficacy of intradermal TA and topical hydroquinone. Each group was treated with either monthly intradermal TA injections or nightly hydroquinone for 3 months. After 4 weeks of treatment, TA initially had a greater improvement. However, after 20 weeks, the overall changes were not significant between the 2 groups.³⁴ Pazyar et al³⁵ conducted a randomized, split-face trial of 49 patients comparing the efficacy of intradermal TA and hydroquinone cream. After 24 weeks of biweekly TA injections or twice-daily hydroquinone, there were no statistically significant differences in the decreased MASI scores between treatments.³⁵ Additional large, double-blind, controlled trials are needed to thoroughly assess the role of intradermal TA in comparison to its treatment counterpart of hydroquinone.

Ebrahimi and Naeini²⁹ conducted a 12-week, double-blind, split-phase trial of 50 Iranian melasma patients, which showed that 27.3% of patients rated the improvement in melasma as excellent, 42.4% as good, and 30.3% as fair after using TA solution 3%. Wu et al³⁶ also showed a total melasma improvement rate of 80.9% in 256 patients with long-term oral use of TA. In a study by Kim et al³¹ (N=245), the mean MASI score considerably decreased after topical TA use, with a total response rate of 95.6%. In another study, Atefi et al³⁷ presented significantly increased levels of satisfaction in patients treated with topical TA 5% vs hydroquinone (P=.015).

Melasma in Patients With Darker Skin Types—Special attention must be given to choosing the appropriate medication in melasma patients with darker skin types, as there is an increased risk for postinflammatory hyperpigmentation. Currently, few randomized controlled trials exist that fulfill the criteria of evaluating pharmacologic options for patients with melasma, and even fewer studies solely focus on patients with darker skin types.³⁸ In addition to treatment advances, patients must be educated on the need to avoid sun exposure when possible or to use photoprotection, especially in the South Asian region, where these practices rarely are taught. Our study provided a unique analysis regarding the efficacy of TA solution 5% for the treatment of melasma in patients of South Asian descent. Clinicians can use these findings as a foundation for treating all patients with melasma but particularly those with darker skin types.

Study Limitations—Our study consisted of 60 patients; although our study had more patients than similar trials, larger studies are needed. Additionally, other variables were excluded from our analysis, such as comorbidities beyond diabetes mellitus and hypertension.

Conclusion

This study contributes to the growing field of melasma therapeutics by evaluating the efficacy of using TA solution 5% for the treatment of melasma in South Asian patients with darker skin types. Clinicians may use our study to broaden their treatment options for a common condition while also addressing the lack of clinical options for patients with darker skin types. Further studies investigating the effectiveness of TA in large clinical trials in humans are warranted to understand the efficacy and the risk for any complications.

Melasma is a complex, long-lasting, acquired dermatologic pigmentation disorder resulting in grey-brown patches that last for more than 3 months. Sun-exposed areas including the nose, cheeks, forehead, and forearms are most likely to be affected.¹ In Southeast Asia, 0.25% to 4% of the population affected by melasma is aged 30 to 40 years.² In particular, melasma is a concern among pregnant women due to increased levels of melanocyte-stimulating hormones (MSHs) and is impacted by genetics, hormonal influence, and exposure to UV light.^3,4 In Pakistan, approximately 46% of women are affected by melasma during pregnancy.^2,5 Although few studies have focused on the clinical approaches to melasma in darker skin types, it continues to disproportionately affect the skin of color population.⁴

The areas of hyperpigmentation seen in melasma exhibit increased deposition of melanin in the epidermis and dermis, but melanocytes are not elevated. However, in areas of hyperpigmentation, the melanocytes are larger and more dendritic and demonstrate an increased level of melanogenesis.⁶ During pregnancy, especially in the third trimester, elevated levels of estrogen, progesterone, and MSH often are found in association with melasma.⁷ Tyrosinase (TYR) activity increases and cellular proliferation is reduced after treatment of melanocytes in culture with β-estradiol.⁸ Sex steroids increase transcription of genes encoding melanogenic enzymes in normal human melanocytes, especially TYR.⁹ These results are consistent with the notable increases in melanin synthesis and TYR activity reported for normal human melanocytes under similar conditions in culture.¹⁰ Because melanocytes contain both cytosolic and nuclear estrogen receptors, melanocytes in patients with melasma may be inherently more sensitive to the stimulatory effects of estrogens and possibly other steroid hormones.¹¹

The current treatment options for melasma have varying levels of success and include topical depigmenting agents such as hydroquinone, tretinoin, azelaic acid, kojic acid, and corticosteroids; dermabrasion; and chemical peels.^12-14 Chemical peels with glycolic acid, salicylic acid, lactic acid, trichloroacetic acid, and phenol, as well as laser therapy, are reliable management options.^13,14 Traditionally, melasma has been treated with a combination of modalities along with photoprotection and trigger avoidance.¹²

The efficacy and safety of the available therapies for melasma are still controversial and require further exploration. In recent years, off-label tranexamic acid (TA) has emerged as a potential therapy for melasma. Although the mechanism of action remains unclear, TA may inhibit melanin synthesis by blocking the interaction between melanocytes and keratinocytes.¹⁵ Tranexamic acid also may reverse the abnormal dermal changes associated with melasma by inhibiting melanogenesis and angiogenesis.¹⁶

Although various therapeutic options exist for melasma, the search for a reliable option in patients with darker skin types continues.¹³ We sought to evaluate the efficacy of TA solution 5% in reducing the severity of melasma in South Asian patients, thereby improving patient outcomes and maximizing patient satisfaction. Topical TA is inexpensive and readily accessible and does not cause systemic side effects. These qualities make it a promising treatment compared to traditional therapies.

Methods

We conducted a randomized controlled trial at Rawalpindi Medical Institute (Punjab, Pakistan). The researchers obtained informed consent for all enrolled patients. Cases were sampled from the original patient population seen at the office using nonprobability consecutive sampling. The sample size was calculated with a 95% CI, margin of error of 9%, and expected percentage of efficacy of 86.1% by using TA solution 5%. South Asian male and female patients aged 20 to 45 years with melasma were included in the analysis. Patients were excluded if they were already taking TA, oral contraceptive pills, or photosensitizing drugs (eg, nonsteroidal anti-inflammatory drugs, tetracyclines, phenytoin, carbamazepine); were pregnant; had chronic kidney disease (creatinine >2.0 mg/dL); had cardiac abnormalities (abnormal electrocardiogram); had hematologic disorders (international normalized ratio >2); or had received another melasma treatment within the last 3 to 6 months.

All enrolled patients underwent a detailed history and physical examination. Patient demographics were subsequently noted, including age, sex, history of diabetes mellitus or hypertension, and duration of melasma. The melasma area and severity index (MASI) score of each patient was calculated at baseline, and a corresponding photograph was taken.

The topical solution was prepared with 5 g of TA dissolved in 10 cc of ethanol at 96 °F, 10 cc of 1,3-butanediol, and distilled water up to 100 cc. The TA solution was applied to the affected areas once daily by the patient for 12 weeks. Each application covered the affected areas completely. Patients were instructed to apply sunscreen with sun protection factor 60 to those same areas for UV protection after 15 minutes of TA application. Biweekly follow-ups were scheduled during the trial, and the MASI score was recorded at these visits. If the mean MASI score was reduced by half after 12 weeks of treatment, then the treatment was considered efficacious with a 95% CI.

The percentage reduction from baseline was calculated as follows: percentage reduction=(baseline score– follow-up score)/baseline score×100.

Statistical Analysis—Data were analyzed in SPSS Statistics 25 (IBM). The quantitative variables of age, duration of melasma, and body mass index were presented as mean (SD). Qualitative variables such as sex, history of diabetes mellitus or hypertension, site of melasma, and efficacy were presented as frequencies and percentages. Mean MASI scores at baseline and 12 weeks posttreatment were compared using a paired t test (P≤.05). Data were stratified for age, sex, history of diabetes mellitus or hypertension, site of melasma, and duration of melasma, and a χ² test was applied to compare efficacy in stratified groups (P≤.05).

Results

Sixty patients were enrolled in the study. Of them, 17 (28.33%) were male, and 43 (71.67%) were female (2:5 ratio). They ranged in age from 20 to 45 years (mean [SD], 31.93 [6.26] years). Thirty-seven patients (61.67%) were aged 31 to 45 years of age (Table 1). The mean (SD) duration of disease was 10.18 (2.10) months. The response to TA was recorded based on patient distribution according to the site of melasma as well as history of diabetes mellitus and hypertension.

Topical TA was found to be efficacious for melasma in 50 (83.33%) patients. The mean (SD) baseline and week 12 MASI scores were 23.15 (5.02) and 12.71 (4.10)(P<.0001), respectively (Table 2). The stratification of efficacy with respect to age, sex, duration of melasma, site of melasma, and history of diabetes mellitus or hypertension is shown in the eTable. The site of melasma was significant with respect to stratification of efficacy. On the forehead, TA was found to be efficacious in 11 patients and nonefficacious in 0 patients (P=.036). In the malar region, it was efficacious in 16 patients and nonefficacious in 1 patient (P=.036). Finally, on the chin, it was efficacious in 23 patients and nonefficacious in 9 patients (P=.036).

Comment

Melasma Presentation and Development—Melasma is a chronic skin condition that more often affects patients with darker skin types. This condition is characterized by hyperpigmentation of skin that is directly exposed to the sun, such as the cheek, nose, forehead, and above the upper lip.¹⁷ Although the mechanism behind how melasma develops is unknown, one theory suggests that UV light can lead to increased plasmin in keratinocytes.¹⁸ This increased plasmin will thereby increase the arachidonic acid and α-MSH, leading to the observed uneven hyperpigmentation that is notable in melasma. Melasma is common in patients using oral contraceptives or expired cosmetic drugs; in those who are pregnant; and in those with liver dysfunction.¹⁸ Melasma has a negative impact on patients’ quality of life because of substantial psychological and social distress. Thus, finding an accessible treatment is imperative.¹⁹

Melasma Management—The most common treatments for melasma have been topical bleaching agents and photoprotection. Combination therapy options include chemical peels, dermabrasion, and laser treatments, though they present with limited efficacy.^17,20 Because melasma focuses on pigmentation correction, topical treatments work to disturb melanocyte pigment production at the enzymatic level.²¹ Tyrosinase is rate limiting in melanin production, as it converts L-tyrosinase to L-3,4-dihydroxyphenylalanine, using copper to interact with L-3,4-dihydroxyphenylalanine as a cofactor in the active site.²² Therefore, tyrosine is a major target for many drugs that have been developed for melasma to decrease melaninization.²¹

Recently, research has focused on the effects of topical, intradermal, and oral TA for melasma.¹⁷ Tranexamic acid most commonly has been used in medicine as a fibrinolytic agent because of its antiplasmin properties. It has been hypothesized that TA can inhibit the release of paracrine melanogenic factors that normally act to stimulate melanocytes.¹⁷ Although studies have supported the safety and efficacy of TA, there remains a lack of clinical studies that are sufficiently powered. No definitive consensus on the use of TA for melasma currently exists, which indicates the need for large-scale, randomized, controlled trials.²³

One trial (N=25) found that TA solution 5% achieved efficacy (>50% reduction in MASI score from baseline) in 86.1% of patients with melasma.²⁴ In another study (N=18), topical TA 5% achieved efficacy (>50% reduction in MASI score) in 86% of patients with melasma.²⁵

Melasma Comorbidities—To determine if certain comorbidities, such as diabetes mellitus or hypertension, influenced the progression of melasma, we stratified the efficacy results for patients with these 2 comorbidities, which showed no significant difference (P=.794 and P=.101, respectively). Thus, the relatively higher prevalence of diabetes mellitus (16 patients) and hypertension (11 patients) did not contribute to the efficacy of TA in lowering MASI scores over the 12-week period, which supports the findings of Doolan and Gupta,²⁶ who investigated the endocrinologic conditions associated with melasma and found no such association with diabetes mellitus or hypertension.

TA Formulations for Melasma—The efficacy of topical TA has been explored in several studies. Six studies with sample sizes of 13 to 50 patients each showed statistically significant differences in MASI scores between baseline and following TA treatment (P<.001).^27-32 Several formulations and regimens were utilized, including TA cream 3% for 12 weeks, TA gel 5% for 12 weeks, TA solution 3% for 12 weeks, TA liposome 5% for 12 weeks, and TA solution 2% for 12 weeks.¹⁸ Additionally, these studies found TA to be effective in limiting dyschromia and decreasing MASI scores. There were no statistically significant differences between formulations and method of application. Topical TA has been found to be just as effective as other treatments for melasma, including intradermal TA injections, topical hydroquinone, and a combination of topical hydroquinone and dexamethasone.¹⁸

Further study of the efficacy of intradermal TA is necessary because many human trials have lacked statistical significance or a control group. Lee et al³² conducted a trial of 100 female patients who received weekly intradermal TA microinjections for 12 weeks. After 8 and 12 weeks, MASI scores decreased significantly (P<.01).³² Similarly, Badran et al³³ observed 60 female patients in 3 trial groups: group A received TA (4 mg/mL) intradermal injections every 2 weeks, group B received TA (10 mg/mL) intradermal injections every 2 weeks, and group C received TA cream 10% twice daily. Although all groups showed improvement in MASI, group B, which had the highest intradermal TA concentration, exhibited the most improvement. Thus, it was determined that intradermal application led to better results, but the cream was still effective.³³

Saki et al³⁴ conducted a randomized, split-face trial of 37 patients comparing the efficacy of intradermal TA and topical hydroquinone. Each group was treated with either monthly intradermal TA injections or nightly hydroquinone for 3 months. After 4 weeks of treatment, TA initially had a greater improvement. However, after 20 weeks, the overall changes were not significant between the 2 groups.³⁴ Pazyar et al³⁵ conducted a randomized, split-face trial of 49 patients comparing the efficacy of intradermal TA and hydroquinone cream. After 24 weeks of biweekly TA injections or twice-daily hydroquinone, there were no statistically significant differences in the decreased MASI scores between treatments.³⁵ Additional large, double-blind, controlled trials are needed to thoroughly assess the role of intradermal TA in comparison to its treatment counterpart of hydroquinone.

Ebrahimi and Naeini²⁹ conducted a 12-week, double-blind, split-phase trial of 50 Iranian melasma patients, which showed that 27.3% of patients rated the improvement in melasma as excellent, 42.4% as good, and 30.3% as fair after using TA solution 3%. Wu et al³⁶ also showed a total melasma improvement rate of 80.9% in 256 patients with long-term oral use of TA. In a study by Kim et al³¹ (N=245), the mean MASI score considerably decreased after topical TA use, with a total response rate of 95.6%. In another study, Atefi et al³⁷ presented significantly increased levels of satisfaction in patients treated with topical TA 5% vs hydroquinone (P=.015).

Melasma in Patients With Darker Skin Types—Special attention must be given to choosing the appropriate medication in melasma patients with darker skin types, as there is an increased risk for postinflammatory hyperpigmentation. Currently, few randomized controlled trials exist that fulfill the criteria of evaluating pharmacologic options for patients with melasma, and even fewer studies solely focus on patients with darker skin types.³⁸ In addition to treatment advances, patients must be educated on the need to avoid sun exposure when possible or to use photoprotection, especially in the South Asian region, where these practices rarely are taught. Our study provided a unique analysis regarding the efficacy of TA solution 5% for the treatment of melasma in patients of South Asian descent. Clinicians can use these findings as a foundation for treating all patients with melasma but particularly those with darker skin types.

Study Limitations—Our study consisted of 60 patients; although our study had more patients than similar trials, larger studies are needed. Additionally, other variables were excluded from our analysis, such as comorbidities beyond diabetes mellitus and hypertension.

Conclusion

This study contributes to the growing field of melasma therapeutics by evaluating the efficacy of using TA solution 5% for the treatment of melasma in South Asian patients with darker skin types. Clinicians may use our study to broaden their treatment options for a common condition while also addressing the lack of clinical options for patients with darker skin types. Further studies investigating the effectiveness of TA in large clinical trials in humans are warranted to understand the efficacy and the risk for any complications.

The Diagnosis: Eccrine Poroma

Histopathology demonstrated epidermal thickening, epidermal protrusions, a well-defined mass of tumor cells that extended from the epidermis down to the dermis, and luminal structures. Poroid cells and ovoid nuclei with basophilic cytoplasm also were evident (Figure 1). Dermoscopy showed papillomatous growth, milky-red areas, and dotted vessels (Figure 2). Reflectance confocal microscopy (RCM) at the spinous layer showed hyporefractile, dark, roundish lumina surrounded by keratinocytes (Figure 3). Based on the histologic, dermoscopic, and RCM findings, our patient was diagnosed with eccrine poroma.

Goldman et al¹ first described poroma in 1956. Poromas, which include eccrine poroma, are a group of benign cutaneous neoplasms arising from the terminal eccrine or apocrine sweat gland ducts.² Histologically, poroid cells appear as cuboidal keratinocytes with monomorphous ovoid nuclei and discrete nucleoli.³ They usually appear as nodules or plaques with colors varying from flesh colored to red, brown, or bluish, and they clinically mimic several benign and malignant skin tumors. The differential diagnosis may include keratoacanthoma, plantar wart, verrucous carcinoma, basal cell carcinoma, and squamous cell carcinoma. Poromas can be of eccrine or apocrine origin.⁴ They also belong to a broad group of neoplasms, including nodular hidradenomas, clear cell hidradenomas, hidroacanthoma simplex, dermal duct tumors, and hidradenomas.⁵ Four subtypes—poroma, poroid hidradenoma, hidroacanthoma simplex, and dermal duct tumor—have been documented.⁶ Because poromas have nonspecific and variable clinical presentations, they often are misdiagnosed as other skin neoplasms, and differentiation may be difficult. For example, some cases of poroma present with follicular, sebaceous, and/or apocrine differentiation, leading to difficulty in diagnosis.

Characteristic features of eccrine poroma seen on dermoscopy and RCM have the potential to aid in the diagnosis compared to histopathology. Marchetti et al⁷ proposed 4 patterns of characteristic dermoscopic findings. Pattern 1 refers to the classic description with bleeding spots, a structureless yellow appearance, milkyred globules, and branched vessels. Patterns 2 and 3 simulate basal cell carcinoma, dermal nevus, or vascular tumors. Pattern 4 refers to tumors that are large in size and resemble keratinizing neoplasms.⁷ Brugués et al⁸ described poromas with the following RCM findings: an atypical honeycomb shape that was well separated from the normal epithelium, hyporefractile nests with atypical cells, lack of palisading, and dark holes. One study described RCM parameters as cords without palisading, dark holes, prominent vascularization, and abundant stroma—findings that were positively associated with poroma in a univariate analysis. These findings assist in distinguishing poromas from other conditions in the differential diagnosis.⁹

There is a substantial overlap in clinical appearance with malignant conditions, including basal cell carcinoma, squamous cell carcinoma, cutaneous metastases, and Paget disease; therefore, the use of dermoscopy and RCM may be helpful in the diagnosis and recognition of specific features, as well as the corresponding patterns of poroma. Poromas commonly display vascularized features due to the variability of dermoscopic patterns of eccrine poroma, and further studies are required to establish the specificity of vascularized features.

Acral lesions are more likely to show the classic clinical features of erythema and exophytic growth. A case of a collision tumor with the verrucous changes of poroma, seborrheic keratosis, and viral wart has been described.10 The verrucous changes may lead to misdiagnosis as plantar warts or other neoplasms. Clinicians also should consider conditions that are induced by friction or trauma. In our patient, dermoscopy and RCM aided in the diagnosis of eccrine poroma due to the interference of prominent overlying verrucous changes.

Treatment of poroma is optional. Deeper lesions can be treated with surgical excision, and superficial lesions may be treated with electrosurgical destruction. Our patient was treated with surgical excision followed by repair of the surgical defect with a double V-Y flap.

The Diagnosis: Eccrine Poroma

Histopathology demonstrated epidermal thickening, epidermal protrusions, a well-defined mass of tumor cells that extended from the epidermis down to the dermis, and luminal structures. Poroid cells and ovoid nuclei with basophilic cytoplasm also were evident (Figure 1). Dermoscopy showed papillomatous growth, milky-red areas, and dotted vessels (Figure 2). Reflectance confocal microscopy (RCM) at the spinous layer showed hyporefractile, dark, roundish lumina surrounded by keratinocytes (Figure 3). Based on the histologic, dermoscopic, and RCM findings, our patient was diagnosed with eccrine poroma.

Goldman et al¹ first described poroma in 1956. Poromas, which include eccrine poroma, are a group of benign cutaneous neoplasms arising from the terminal eccrine or apocrine sweat gland ducts.² Histologically, poroid cells appear as cuboidal keratinocytes with monomorphous ovoid nuclei and discrete nucleoli.³ They usually appear as nodules or plaques with colors varying from flesh colored to red, brown, or bluish, and they clinically mimic several benign and malignant skin tumors. The differential diagnosis may include keratoacanthoma, plantar wart, verrucous carcinoma, basal cell carcinoma, and squamous cell carcinoma. Poromas can be of eccrine or apocrine origin.⁴ They also belong to a broad group of neoplasms, including nodular hidradenomas, clear cell hidradenomas, hidroacanthoma simplex, dermal duct tumors, and hidradenomas.⁵ Four subtypes—poroma, poroid hidradenoma, hidroacanthoma simplex, and dermal duct tumor—have been documented.⁶ Because poromas have nonspecific and variable clinical presentations, they often are misdiagnosed as other skin neoplasms, and differentiation may be difficult. For example, some cases of poroma present with follicular, sebaceous, and/or apocrine differentiation, leading to difficulty in diagnosis.

Characteristic features of eccrine poroma seen on dermoscopy and RCM have the potential to aid in the diagnosis compared to histopathology. Marchetti et al⁷ proposed 4 patterns of characteristic dermoscopic findings. Pattern 1 refers to the classic description with bleeding spots, a structureless yellow appearance, milkyred globules, and branched vessels. Patterns 2 and 3 simulate basal cell carcinoma, dermal nevus, or vascular tumors. Pattern 4 refers to tumors that are large in size and resemble keratinizing neoplasms.⁷ Brugués et al⁸ described poromas with the following RCM findings: an atypical honeycomb shape that was well separated from the normal epithelium, hyporefractile nests with atypical cells, lack of palisading, and dark holes. One study described RCM parameters as cords without palisading, dark holes, prominent vascularization, and abundant stroma—findings that were positively associated with poroma in a univariate analysis. These findings assist in distinguishing poromas from other conditions in the differential diagnosis.⁹

There is a substantial overlap in clinical appearance with malignant conditions, including basal cell carcinoma, squamous cell carcinoma, cutaneous metastases, and Paget disease; therefore, the use of dermoscopy and RCM may be helpful in the diagnosis and recognition of specific features, as well as the corresponding patterns of poroma. Poromas commonly display vascularized features due to the variability of dermoscopic patterns of eccrine poroma, and further studies are required to establish the specificity of vascularized features.

Acral lesions are more likely to show the classic clinical features of erythema and exophytic growth. A case of a collision tumor with the verrucous changes of poroma, seborrheic keratosis, and viral wart has been described.10 The verrucous changes may lead to misdiagnosis as plantar warts or other neoplasms. Clinicians also should consider conditions that are induced by friction or trauma. In our patient, dermoscopy and RCM aided in the diagnosis of eccrine poroma due to the interference of prominent overlying verrucous changes.

Treatment of poroma is optional. Deeper lesions can be treated with surgical excision, and superficial lesions may be treated with electrosurgical destruction. Our patient was treated with surgical excision followed by repair of the surgical defect with a double V-Y flap.

The Diagnosis: Eccrine Poroma

Histopathology demonstrated epidermal thickening, epidermal protrusions, a well-defined mass of tumor cells that extended from the epidermis down to the dermis, and luminal structures. Poroid cells and ovoid nuclei with basophilic cytoplasm also were evident (Figure 1). Dermoscopy showed papillomatous growth, milky-red areas, and dotted vessels (Figure 2). Reflectance confocal microscopy (RCM) at the spinous layer showed hyporefractile, dark, roundish lumina surrounded by keratinocytes (Figure 3). Based on the histologic, dermoscopic, and RCM findings, our patient was diagnosed with eccrine poroma.

Goldman et al¹ first described poroma in 1956. Poromas, which include eccrine poroma, are a group of benign cutaneous neoplasms arising from the terminal eccrine or apocrine sweat gland ducts.² Histologically, poroid cells appear as cuboidal keratinocytes with monomorphous ovoid nuclei and discrete nucleoli.³ They usually appear as nodules or plaques with colors varying from flesh colored to red, brown, or bluish, and they clinically mimic several benign and malignant skin tumors. The differential diagnosis may include keratoacanthoma, plantar wart, verrucous carcinoma, basal cell carcinoma, and squamous cell carcinoma. Poromas can be of eccrine or apocrine origin.⁴ They also belong to a broad group of neoplasms, including nodular hidradenomas, clear cell hidradenomas, hidroacanthoma simplex, dermal duct tumors, and hidradenomas.⁵ Four subtypes—poroma, poroid hidradenoma, hidroacanthoma simplex, and dermal duct tumor—have been documented.⁶ Because poromas have nonspecific and variable clinical presentations, they often are misdiagnosed as other skin neoplasms, and differentiation may be difficult. For example, some cases of poroma present with follicular, sebaceous, and/or apocrine differentiation, leading to difficulty in diagnosis.

Characteristic features of eccrine poroma seen on dermoscopy and RCM have the potential to aid in the diagnosis compared to histopathology. Marchetti et al⁷ proposed 4 patterns of characteristic dermoscopic findings. Pattern 1 refers to the classic description with bleeding spots, a structureless yellow appearance, milkyred globules, and branched vessels. Patterns 2 and 3 simulate basal cell carcinoma, dermal nevus, or vascular tumors. Pattern 4 refers to tumors that are large in size and resemble keratinizing neoplasms.⁷ Brugués et al⁸ described poromas with the following RCM findings: an atypical honeycomb shape that was well separated from the normal epithelium, hyporefractile nests with atypical cells, lack of palisading, and dark holes. One study described RCM parameters as cords without palisading, dark holes, prominent vascularization, and abundant stroma—findings that were positively associated with poroma in a univariate analysis. These findings assist in distinguishing poromas from other conditions in the differential diagnosis.⁹

There is a substantial overlap in clinical appearance with malignant conditions, including basal cell carcinoma, squamous cell carcinoma, cutaneous metastases, and Paget disease; therefore, the use of dermoscopy and RCM may be helpful in the diagnosis and recognition of specific features, as well as the corresponding patterns of poroma. Poromas commonly display vascularized features due to the variability of dermoscopic patterns of eccrine poroma, and further studies are required to establish the specificity of vascularized features.

Acral lesions are more likely to show the classic clinical features of erythema and exophytic growth. A case of a collision tumor with the verrucous changes of poroma, seborrheic keratosis, and viral wart has been described.10 The verrucous changes may lead to misdiagnosis as plantar warts or other neoplasms. Clinicians also should consider conditions that are induced by friction or trauma. In our patient, dermoscopy and RCM aided in the diagnosis of eccrine poroma due to the interference of prominent overlying verrucous changes.

Treatment of poroma is optional. Deeper lesions can be treated with surgical excision, and superficial lesions may be treated with electrosurgical destruction. Our patient was treated with surgical excision followed by repair of the surgical defect with a double V-Y flap.

The Diagnosis: Monilethrix

A diagnosis of monilethrix was rendered based on the clinical and trichoscopic findings. Simple surveillance of the patient’s condition and prevention of further hair trauma were proposed as management options.

Monilethrix is a hair shaft disorder that is inherited in a predominantly autosomal-dominant pattern with variable expressiveness and penetrance resulting from heterozygous mutations in hair keratin genes KRT81, KRT83, and KRT86 in a region of chromosome 12q13.13.^1,2 An autosomalrecessive form has been described with mutation in desmoglein 4, but it differs from the classical form by the variable periodicity of the region between the nodules.^3,4

The morphologic alteration consists of the formation of fusiform nodules of normal structure alternated with narrow and dystrophic constrictions (Figure). These internodes are fragile areas that cause breakage at constricted points.⁵ Clinically, monilethrix presents as areas of focal or diffuse alopecia with frequent involvement of the terminal follicles, mainly in areas of friction. The hair is normal at birth due to the predominance of lanugo in the neonatal period, but it subsequently is replaced by abnormal hairs in the first months of life.⁶ Initial clinical signs begin to appear when the terminal hairs begin to form.⁷ Although rarer, the eyebrows and eyelashes, as well as the axillary, pubic, and body hair, may be involved.⁵

Other hair shaft anomalies merit consideration in the differential diagnosis of monilethrix, including pseudomonilethrix, pressure alopecia, trichorrhexis invaginata, ectodermal dysplasia, tinea capitis, and trichothiodystrophy.⁶ The diagnosis is reached by clinical history and physical examination. Trichoscopy and light microscopy are used to confirm the diagnosis. Trichoscopic examination shows markedly higher rates of anagen hair. The shafts examined in our patient revealed 0.7- to 1-mm intervals between nodes. Hair can be better visualized under a polarized microscope, and the condition can be distinguished from pseudomonilethrix using this approach.^5,6 In our patient, the diagnosis was made based on light microscopy and trichoscopic findings with no genetic testing; however, genetic testing for the classic mutations of the keratin genes would be desirable to confirm the diagnosis but was not done in our patient.⁶ The prognosis of monilethrix is variable; most cases persist into adulthood, though spontaneous improvement may occur with advancing age, during summer, and during pregnancy.⁸

There is no definitive therapy for monilethrix. Although there have been reports of cases treated with systemic corticosteroids, oral retinoids, topical minoxidil, vitamins, and peeling ointments (desquamative oil), the cornerstone of management is protecting the hair against traumatic procedures such as excessive combing, brushing, and friction, as well as parent and patient education about the benign nature of the condition.9 Additionally, some cases have shown improvement with minoxidil solution at 2% and 5% concentrations, oral minoxidil, or acitretin.^7-9

The Diagnosis: Monilethrix

A diagnosis of monilethrix was rendered based on the clinical and trichoscopic findings. Simple surveillance of the patient’s condition and prevention of further hair trauma were proposed as management options.

Monilethrix is a hair shaft disorder that is inherited in a predominantly autosomal-dominant pattern with variable expressiveness and penetrance resulting from heterozygous mutations in hair keratin genes KRT81, KRT83, and KRT86 in a region of chromosome 12q13.13.^1,2 An autosomalrecessive form has been described with mutation in desmoglein 4, but it differs from the classical form by the variable periodicity of the region between the nodules.^3,4

The morphologic alteration consists of the formation of fusiform nodules of normal structure alternated with narrow and dystrophic constrictions (Figure). These internodes are fragile areas that cause breakage at constricted points.⁵ Clinically, monilethrix presents as areas of focal or diffuse alopecia with frequent involvement of the terminal follicles, mainly in areas of friction. The hair is normal at birth due to the predominance of lanugo in the neonatal period, but it subsequently is replaced by abnormal hairs in the first months of life.⁶ Initial clinical signs begin to appear when the terminal hairs begin to form.⁷ Although rarer, the eyebrows and eyelashes, as well as the axillary, pubic, and body hair, may be involved.⁵

Other hair shaft anomalies merit consideration in the differential diagnosis of monilethrix, including pseudomonilethrix, pressure alopecia, trichorrhexis invaginata, ectodermal dysplasia, tinea capitis, and trichothiodystrophy.⁶ The diagnosis is reached by clinical history and physical examination. Trichoscopy and light microscopy are used to confirm the diagnosis. Trichoscopic examination shows markedly higher rates of anagen hair. The shafts examined in our patient revealed 0.7- to 1-mm intervals between nodes. Hair can be better visualized under a polarized microscope, and the condition can be distinguished from pseudomonilethrix using this approach.^5,6 In our patient, the diagnosis was made based on light microscopy and trichoscopic findings with no genetic testing; however, genetic testing for the classic mutations of the keratin genes would be desirable to confirm the diagnosis but was not done in our patient.⁶ The prognosis of monilethrix is variable; most cases persist into adulthood, though spontaneous improvement may occur with advancing age, during summer, and during pregnancy.⁸

There is no definitive therapy for monilethrix. Although there have been reports of cases treated with systemic corticosteroids, oral retinoids, topical minoxidil, vitamins, and peeling ointments (desquamative oil), the cornerstone of management is protecting the hair against traumatic procedures such as excessive combing, brushing, and friction, as well as parent and patient education about the benign nature of the condition.9 Additionally, some cases have shown improvement with minoxidil solution at 2% and 5% concentrations, oral minoxidil, or acitretin.^7-9

The Diagnosis: Monilethrix

A diagnosis of monilethrix was rendered based on the clinical and trichoscopic findings. Simple surveillance of the patient’s condition and prevention of further hair trauma were proposed as management options.

Monilethrix is a hair shaft disorder that is inherited in a predominantly autosomal-dominant pattern with variable expressiveness and penetrance resulting from heterozygous mutations in hair keratin genes KRT81, KRT83, and KRT86 in a region of chromosome 12q13.13.^1,2 An autosomalrecessive form has been described with mutation in desmoglein 4, but it differs from the classical form by the variable periodicity of the region between the nodules.^3,4

The morphologic alteration consists of the formation of fusiform nodules of normal structure alternated with narrow and dystrophic constrictions (Figure). These internodes are fragile areas that cause breakage at constricted points.⁵ Clinically, monilethrix presents as areas of focal or diffuse alopecia with frequent involvement of the terminal follicles, mainly in areas of friction. The hair is normal at birth due to the predominance of lanugo in the neonatal period, but it subsequently is replaced by abnormal hairs in the first months of life.⁶ Initial clinical signs begin to appear when the terminal hairs begin to form.⁷ Although rarer, the eyebrows and eyelashes, as well as the axillary, pubic, and body hair, may be involved.⁵

Other hair shaft anomalies merit consideration in the differential diagnosis of monilethrix, including pseudomonilethrix, pressure alopecia, trichorrhexis invaginata, ectodermal dysplasia, tinea capitis, and trichothiodystrophy.⁶ The diagnosis is reached by clinical history and physical examination. Trichoscopy and light microscopy are used to confirm the diagnosis. Trichoscopic examination shows markedly higher rates of anagen hair. The shafts examined in our patient revealed 0.7- to 1-mm intervals between nodes. Hair can be better visualized under a polarized microscope, and the condition can be distinguished from pseudomonilethrix using this approach.^5,6 In our patient, the diagnosis was made based on light microscopy and trichoscopic findings with no genetic testing; however, genetic testing for the classic mutations of the keratin genes would be desirable to confirm the diagnosis but was not done in our patient.⁶ The prognosis of monilethrix is variable; most cases persist into adulthood, though spontaneous improvement may occur with advancing age, during summer, and during pregnancy.⁸

There is no definitive therapy for monilethrix. Although there have been reports of cases treated with systemic corticosteroids, oral retinoids, topical minoxidil, vitamins, and peeling ointments (desquamative oil), the cornerstone of management is protecting the hair against traumatic procedures such as excessive combing, brushing, and friction, as well as parent and patient education about the benign nature of the condition.9 Additionally, some cases have shown improvement with minoxidil solution at 2% and 5% concentrations, oral minoxidil, or acitretin.^7-9

To the Editor:

Granulomatous dermatitis (GD) has been described as a rare side effect of MEK and BRAF inhibitor use in the treatment of BRAF V600E mutation–positive metastatic melanoma. As the utilization of BRAF and MEK inhibitors increases for the treatment of a variety of cancers, it is essential that clinicians and pathologists recognize GD as a potential cutaneous manifestation. We present the case of a 52-year-old woman who developed GD while being treated with vemurafenib and cobimetinib for BRAF V600E mutation–positive metastatic cholangiocarcinoma.

A 52-year-old White woman presented with faint patches of nonpalpable violaceous mottling that extended distally to proximally from the ankles to the thighs on the medial aspects of both legs. She was diagnosed with cholangiocarcinoma 10 months prior, with metastases to the lung, liver, and sternum. She underwent treatment with gemcitabine and cisplatin therapy. Computed tomography after several treatment cycles revealed progressive disease with multiple pulmonary nodules as well as metastatic intrathoracic and abdominal adenopathy. Treatment with gemcitabine and cisplatin failed to produce a favorable response and was discontinued after 6 treatment cycles.

Genomic testing performed at the time of diagnosis revealed a positive mutation for BRAF V600E. The patient subsequently enrolled in a clinical trial and started treatment with the BRAF inhibitor vemurafenib and the MEK inhibitor cobimetinib. She developed sun sensitivity and multiple sunburns after starting these therapies. The patient tolerated the next few cycles of therapy well with only moderate concerns of dry sensitive skin.

During the sixth cycle of therapy, she presented to dermatology after developing a rash. Over the next 2 weeks, similar lesions appeared on the arms. The patient denied the use of any new lotions, soaps, or other medications. Punch biopsies of the right forearm and right medial thigh revealed nonnecrotizing granulomas in the superficial dermis that extended into the subcutaneous adipose tissue (Figure 1). Surrounding chronic inflammation was scant, and the presence of rare eosinophils was noted (Figure 2). The histiocytes were highlighted by a CD68 immunohistochemical stain. An auramine-O special stain test was negative for acid-fast bacilli, and a Grocott methenamine-silver special stain test for fungal organisms was negative. These findings were consistent with GD. Computed tomography of the chest performed 2 months prior and 1 month after biopsy of the skin lesions revealed no axillary, mediastinal, or hilar lymphadenopathy. The calcium level at the time of skin biopsy was within reference range.

A topical steroid was prescribed; however, it was not utilized by the patient. Within 2 months of onset, the GD lesions resolved with no treatment. The GD lesions did not affect the patient’s enrollment in the clinical trial, and no dose reductions were made. Due to progressive disease with metastases to the brain, the patient eventually discontinued the clinical trial.

BRAF inhibitors are US Food and Drug Administration approved for the treatment of metastatic melanoma to deactivate the serine-threonine kinase BRAF gene mutation, which leads to decreased generation and survival of melanoma cells.^1,2 Vemurafenib, dabrafenib, and encorafenib are the only BRAF inhibitors approved in the United States.³ The most common side effects of vemurafenib include arthralgia, fatigue, rash, and photosensitivity.^1,4 There are 4 MEK inhibitors currently available in the United States: cobimetinib, trametinib, selumetinib and binimetinib. The addition of a MEK inhibitor to BRAF inhibitor therapy has shown increased patient response rates and prolonged survival in 3 phase 3 studies.^5-10

Response rates remain low in the treatment of advanced cholangiocarcinoma with standard chemotherapy. Recent research has explored if targeted therapies at the molecular level would be of benefit.¹¹ Our patient was enrolled in the American Society of Clinical Oncology Targeted Agent and Profiling Utilization Registry (TAPUR) trial, a phase 2, prospective, nonrandomized trial that matches eligible participants to US Food and Drug Administration–approved study medications based on specific data from their molecular testing results.¹² Some of the most common mutations in intrahepatic cholangiocarcinoma include HER2, KRAS, MET, and BRAF.^13-17 Our patient’s molecular test results were positive for a BRAF V600E–positive mutation, and she subsequently started therapy with vemurafenib and cobimetinib. The use of personalized genomic treatment approaches for BRAF V600E mutation–positive cholangiocarcinoma has produced a dramatic patient response to BRAF and MEK inhibitor combination therapies.^11,18-20

Drug-induced GD most likely is caused by vascular insults that lead to deposition of immune complexes in vessels causing inflammation and a consequent granulomatous infiltrate.^21,22 Although cordlike lesions in the subcutaneous tissue on the trunk commonly are reported, the presentation of GD can vary considerably. Other presentations include areas of violaceous or erythematous patches or plaques on the limbs, intertriginous areas, and upper trunk. Diffuse macular erythema or small flesh-colored papules also can be observed.²³

Granulomatous dermatitis secondary to drug reactions can have varying morphologies. The infiltrate often can have an interstitial appearance with the presence of lymphocytes, plasma cells, histiocytes, eosinophils, and multinucleated giant cells.²⁴ These findings can be confused with interstitial granuloma annulare. Other cases, such as in our patient, can have discrete granulomata formation with a sarcoidlike appearance. These naked granulomas lack surrounding inflammation and suggest a differential diagnosis of sarcoidosis and infection. Use of immune checkpoint inhibitors (CIs) and kinase inhibitors has been proven to cause sarcoidosislike reactions.²⁵ The development of granulomatous/sarcoidlike lesions associated with the use of BRAF and MEK inhibitors may clinically and radiographically mimic disease recurrence. An awareness of this type of reaction by clinicians and pathologists is important to ensure appropriate management in patients who develop GD.²⁶

Checkpoint inhibitor–induced GD that remains asymptomatic does not necessarily warrant treatment; however, corticosteroid use and elimination of CI therapies have resolved GD in prior cases. Responsiveness of the cancer to CI therapy and severity of GD symptoms should be considered before discontinuation of a CI trial.²⁵

One case report described complete resolution of a GD eruption without interruption of the scheduled BRAF and MEK inhibitor therapies for the treatment of metastatic melanoma. There was no reported use of a steroidal cream or other topical medication to aid in controlling the eruption.²⁷ The exact mechanism of how GD resolves while continuing therapy is unknown; however, it has been suggested that a GD eruption may be the consequence of a BRAF and MEK inhibitor–mediated immune response against a subclinical area of metastatic melanoma.²⁸ If the immune response successfully eliminates the subclinical tumor, one could postulate that the inflammatory response and granulomatous eruption would resolve. Future studies are necessary to further elucidate the exact mechanisms involved.

There have been several case reports of GD with vemurafenib treatment,^29,30 1 report of GD and erythema induratum with vemurafenib and cobimetinib treatment,³¹ 2 reports of GD with dabrafenib treatment,^27,30 and a few reports of GD with the BRAF inhibitor dabrafenib combined with the MEK inhibitor trametinib,^28,32,33 all for the treatment of metastatic melanoma. Additionally, a report described a 3-year-old boy who developed GD secondary to vemurafenib for the treatment of Langerhans cell histiocytosis.³⁴ We present a unique case of BRAF and MEK inhibitor therapy–induced GD in the treatment of metastatic cholangiocarcinoma with vemurafenib and cobimetinib.

BRAF and MEK inhibitor therapy is used in patients with metastatic melanomas with a positive BRAF V600E mutation. Due to advancements in next-generation DNA sequencing, these therapies also are being tested in clinical trials for use in the treatment of other cancers with the same checkpoint mutation, such as metastatic cholangiocarcinoma. Cutaneous reactions frequently are documented side effects that occur during treatment with BRAF and MEK inhibitors; GD is an uncommon finding. As the utilization of BRAF and MEK inhibitors increases for the treatment of a variety of other cancers, it is essential that clinicians and pathologists recognize GD as a potential cutaneous manifestation.

To the Editor:

Granulomatous dermatitis (GD) has been described as a rare side effect of MEK and BRAF inhibitor use in the treatment of BRAF V600E mutation–positive metastatic melanoma. As the utilization of BRAF and MEK inhibitors increases for the treatment of a variety of cancers, it is essential that clinicians and pathologists recognize GD as a potential cutaneous manifestation. We present the case of a 52-year-old woman who developed GD while being treated with vemurafenib and cobimetinib for BRAF V600E mutation–positive metastatic cholangiocarcinoma.

A 52-year-old White woman presented with faint patches of nonpalpable violaceous mottling that extended distally to proximally from the ankles to the thighs on the medial aspects of both legs. She was diagnosed with cholangiocarcinoma 10 months prior, with metastases to the lung, liver, and sternum. She underwent treatment with gemcitabine and cisplatin therapy. Computed tomography after several treatment cycles revealed progressive disease with multiple pulmonary nodules as well as metastatic intrathoracic and abdominal adenopathy. Treatment with gemcitabine and cisplatin failed to produce a favorable response and was discontinued after 6 treatment cycles.

Genomic testing performed at the time of diagnosis revealed a positive mutation for BRAF V600E. The patient subsequently enrolled in a clinical trial and started treatment with the BRAF inhibitor vemurafenib and the MEK inhibitor cobimetinib. She developed sun sensitivity and multiple sunburns after starting these therapies. The patient tolerated the next few cycles of therapy well with only moderate concerns of dry sensitive skin.

During the sixth cycle of therapy, she presented to dermatology after developing a rash. Over the next 2 weeks, similar lesions appeared on the arms. The patient denied the use of any new lotions, soaps, or other medications. Punch biopsies of the right forearm and right medial thigh revealed nonnecrotizing granulomas in the superficial dermis that extended into the subcutaneous adipose tissue (Figure 1). Surrounding chronic inflammation was scant, and the presence of rare eosinophils was noted (Figure 2). The histiocytes were highlighted by a CD68 immunohistochemical stain. An auramine-O special stain test was negative for acid-fast bacilli, and a Grocott methenamine-silver special stain test for fungal organisms was negative. These findings were consistent with GD. Computed tomography of the chest performed 2 months prior and 1 month after biopsy of the skin lesions revealed no axillary, mediastinal, or hilar lymphadenopathy. The calcium level at the time of skin biopsy was within reference range.

A topical steroid was prescribed; however, it was not utilized by the patient. Within 2 months of onset, the GD lesions resolved with no treatment. The GD lesions did not affect the patient’s enrollment in the clinical trial, and no dose reductions were made. Due to progressive disease with metastases to the brain, the patient eventually discontinued the clinical trial.

BRAF inhibitors are US Food and Drug Administration approved for the treatment of metastatic melanoma to deactivate the serine-threonine kinase BRAF gene mutation, which leads to decreased generation and survival of melanoma cells.^1,2 Vemurafenib, dabrafenib, and encorafenib are the only BRAF inhibitors approved in the United States.³ The most common side effects of vemurafenib include arthralgia, fatigue, rash, and photosensitivity.^1,4 There are 4 MEK inhibitors currently available in the United States: cobimetinib, trametinib, selumetinib and binimetinib. The addition of a MEK inhibitor to BRAF inhibitor therapy has shown increased patient response rates and prolonged survival in 3 phase 3 studies.^5-10

Response rates remain low in the treatment of advanced cholangiocarcinoma with standard chemotherapy. Recent research has explored if targeted therapies at the molecular level would be of benefit.¹¹ Our patient was enrolled in the American Society of Clinical Oncology Targeted Agent and Profiling Utilization Registry (TAPUR) trial, a phase 2, prospective, nonrandomized trial that matches eligible participants to US Food and Drug Administration–approved study medications based on specific data from their molecular testing results.¹² Some of the most common mutations in intrahepatic cholangiocarcinoma include HER2, KRAS, MET, and BRAF.^13-17 Our patient’s molecular test results were positive for a BRAF V600E–positive mutation, and she subsequently started therapy with vemurafenib and cobimetinib. The use of personalized genomic treatment approaches for BRAF V600E mutation–positive cholangiocarcinoma has produced a dramatic patient response to BRAF and MEK inhibitor combination therapies.^11,18-20

Drug-induced GD most likely is caused by vascular insults that lead to deposition of immune complexes in vessels causing inflammation and a consequent granulomatous infiltrate.^21,22 Although cordlike lesions in the subcutaneous tissue on the trunk commonly are reported, the presentation of GD can vary considerably. Other presentations include areas of violaceous or erythematous patches or plaques on the limbs, intertriginous areas, and upper trunk. Diffuse macular erythema or small flesh-colored papules also can be observed.²³

Granulomatous dermatitis secondary to drug reactions can have varying morphologies. The infiltrate often can have an interstitial appearance with the presence of lymphocytes, plasma cells, histiocytes, eosinophils, and multinucleated giant cells.²⁴ These findings can be confused with interstitial granuloma annulare. Other cases, such as in our patient, can have discrete granulomata formation with a sarcoidlike appearance. These naked granulomas lack surrounding inflammation and suggest a differential diagnosis of sarcoidosis and infection. Use of immune checkpoint inhibitors (CIs) and kinase inhibitors has been proven to cause sarcoidosislike reactions.²⁵ The development of granulomatous/sarcoidlike lesions associated with the use of BRAF and MEK inhibitors may clinically and radiographically mimic disease recurrence. An awareness of this type of reaction by clinicians and pathologists is important to ensure appropriate management in patients who develop GD.²⁶

Checkpoint inhibitor–induced GD that remains asymptomatic does not necessarily warrant treatment; however, corticosteroid use and elimination of CI therapies have resolved GD in prior cases. Responsiveness of the cancer to CI therapy and severity of GD symptoms should be considered before discontinuation of a CI trial.²⁵

One case report described complete resolution of a GD eruption without interruption of the scheduled BRAF and MEK inhibitor therapies for the treatment of metastatic melanoma. There was no reported use of a steroidal cream or other topical medication to aid in controlling the eruption.²⁷ The exact mechanism of how GD resolves while continuing therapy is unknown; however, it has been suggested that a GD eruption may be the consequence of a BRAF and MEK inhibitor–mediated immune response against a subclinical area of metastatic melanoma.²⁸ If the immune response successfully eliminates the subclinical tumor, one could postulate that the inflammatory response and granulomatous eruption would resolve. Future studies are necessary to further elucidate the exact mechanisms involved.

There have been several case reports of GD with vemurafenib treatment,^29,30 1 report of GD and erythema induratum with vemurafenib and cobimetinib treatment,³¹ 2 reports of GD with dabrafenib treatment,^27,30 and a few reports of GD with the BRAF inhibitor dabrafenib combined with the MEK inhibitor trametinib,^28,32,33 all for the treatment of metastatic melanoma. Additionally, a report described a 3-year-old boy who developed GD secondary to vemurafenib for the treatment of Langerhans cell histiocytosis.³⁴ We present a unique case of BRAF and MEK inhibitor therapy–induced GD in the treatment of metastatic cholangiocarcinoma with vemurafenib and cobimetinib.

BRAF and MEK inhibitor therapy is used in patients with metastatic melanomas with a positive BRAF V600E mutation. Due to advancements in next-generation DNA sequencing, these therapies also are being tested in clinical trials for use in the treatment of other cancers with the same checkpoint mutation, such as metastatic cholangiocarcinoma. Cutaneous reactions frequently are documented side effects that occur during treatment with BRAF and MEK inhibitors; GD is an uncommon finding. As the utilization of BRAF and MEK inhibitors increases for the treatment of a variety of other cancers, it is essential that clinicians and pathologists recognize GD as a potential cutaneous manifestation.

To the Editor:

Granulomatous dermatitis (GD) has been described as a rare side effect of MEK and BRAF inhibitor use in the treatment of BRAF V600E mutation–positive metastatic melanoma. As the utilization of BRAF and MEK inhibitors increases for the treatment of a variety of cancers, it is essential that clinicians and pathologists recognize GD as a potential cutaneous manifestation. We present the case of a 52-year-old woman who developed GD while being treated with vemurafenib and cobimetinib for BRAF V600E mutation–positive metastatic cholangiocarcinoma.

A 52-year-old White woman presented with faint patches of nonpalpable violaceous mottling that extended distally to proximally from the ankles to the thighs on the medial aspects of both legs. She was diagnosed with cholangiocarcinoma 10 months prior, with metastases to the lung, liver, and sternum. She underwent treatment with gemcitabine and cisplatin therapy. Computed tomography after several treatment cycles revealed progressive disease with multiple pulmonary nodules as well as metastatic intrathoracic and abdominal adenopathy. Treatment with gemcitabine and cisplatin failed to produce a favorable response and was discontinued after 6 treatment cycles.

Genomic testing performed at the time of diagnosis revealed a positive mutation for BRAF V600E. The patient subsequently enrolled in a clinical trial and started treatment with the BRAF inhibitor vemurafenib and the MEK inhibitor cobimetinib. She developed sun sensitivity and multiple sunburns after starting these therapies. The patient tolerated the next few cycles of therapy well with only moderate concerns of dry sensitive skin.

During the sixth cycle of therapy, she presented to dermatology after developing a rash. Over the next 2 weeks, similar lesions appeared on the arms. The patient denied the use of any new lotions, soaps, or other medications. Punch biopsies of the right forearm and right medial thigh revealed nonnecrotizing granulomas in the superficial dermis that extended into the subcutaneous adipose tissue (Figure 1). Surrounding chronic inflammation was scant, and the presence of rare eosinophils was noted (Figure 2). The histiocytes were highlighted by a CD68 immunohistochemical stain. An auramine-O special stain test was negative for acid-fast bacilli, and a Grocott methenamine-silver special stain test for fungal organisms was negative. These findings were consistent with GD. Computed tomography of the chest performed 2 months prior and 1 month after biopsy of the skin lesions revealed no axillary, mediastinal, or hilar lymphadenopathy. The calcium level at the time of skin biopsy was within reference range.

A topical steroid was prescribed; however, it was not utilized by the patient. Within 2 months of onset, the GD lesions resolved with no treatment. The GD lesions did not affect the patient’s enrollment in the clinical trial, and no dose reductions were made. Due to progressive disease with metastases to the brain, the patient eventually discontinued the clinical trial.

BRAF inhibitors are US Food and Drug Administration approved for the treatment of metastatic melanoma to deactivate the serine-threonine kinase BRAF gene mutation, which leads to decreased generation and survival of melanoma cells.^1,2 Vemurafenib, dabrafenib, and encorafenib are the only BRAF inhibitors approved in the United States.³ The most common side effects of vemurafenib include arthralgia, fatigue, rash, and photosensitivity.^1,4 There are 4 MEK inhibitors currently available in the United States: cobimetinib, trametinib, selumetinib and binimetinib. The addition of a MEK inhibitor to BRAF inhibitor therapy has shown increased patient response rates and prolonged survival in 3 phase 3 studies.^5-10

Response rates remain low in the treatment of advanced cholangiocarcinoma with standard chemotherapy. Recent research has explored if targeted therapies at the molecular level would be of benefit.¹¹ Our patient was enrolled in the American Society of Clinical Oncology Targeted Agent and Profiling Utilization Registry (TAPUR) trial, a phase 2, prospective, nonrandomized trial that matches eligible participants to US Food and Drug Administration–approved study medications based on specific data from their molecular testing results.¹² Some of the most common mutations in intrahepatic cholangiocarcinoma include HER2, KRAS, MET, and BRAF.^13-17 Our patient’s molecular test results were positive for a BRAF V600E–positive mutation, and she subsequently started therapy with vemurafenib and cobimetinib. The use of personalized genomic treatment approaches for BRAF V600E mutation–positive cholangiocarcinoma has produced a dramatic patient response to BRAF and MEK inhibitor combination therapies.^11,18-20

Drug-induced GD most likely is caused by vascular insults that lead to deposition of immune complexes in vessels causing inflammation and a consequent granulomatous infiltrate.^21,22 Although cordlike lesions in the subcutaneous tissue on the trunk commonly are reported, the presentation of GD can vary considerably. Other presentations include areas of violaceous or erythematous patches or plaques on the limbs, intertriginous areas, and upper trunk. Diffuse macular erythema or small flesh-colored papules also can be observed.²³

Granulomatous dermatitis secondary to drug reactions can have varying morphologies. The infiltrate often can have an interstitial appearance with the presence of lymphocytes, plasma cells, histiocytes, eosinophils, and multinucleated giant cells.²⁴ These findings can be confused with interstitial granuloma annulare. Other cases, such as in our patient, can have discrete granulomata formation with a sarcoidlike appearance. These naked granulomas lack surrounding inflammation and suggest a differential diagnosis of sarcoidosis and infection. Use of immune checkpoint inhibitors (CIs) and kinase inhibitors has been proven to cause sarcoidosislike reactions.²⁵ The development of granulomatous/sarcoidlike lesions associated with the use of BRAF and MEK inhibitors may clinically and radiographically mimic disease recurrence. An awareness of this type of reaction by clinicians and pathologists is important to ensure appropriate management in patients who develop GD.²⁶

Checkpoint inhibitor–induced GD that remains asymptomatic does not necessarily warrant treatment; however, corticosteroid use and elimination of CI therapies have resolved GD in prior cases. Responsiveness of the cancer to CI therapy and severity of GD symptoms should be considered before discontinuation of a CI trial.²⁵

One case report described complete resolution of a GD eruption without interruption of the scheduled BRAF and MEK inhibitor therapies for the treatment of metastatic melanoma. There was no reported use of a steroidal cream or other topical medication to aid in controlling the eruption.²⁷ The exact mechanism of how GD resolves while continuing therapy is unknown; however, it has been suggested that a GD eruption may be the consequence of a BRAF and MEK inhibitor–mediated immune response against a subclinical area of metastatic melanoma.²⁸ If the immune response successfully eliminates the subclinical tumor, one could postulate that the inflammatory response and granulomatous eruption would resolve. Future studies are necessary to further elucidate the exact mechanisms involved.

There have been several case reports of GD with vemurafenib treatment,^29,30 1 report of GD and erythema induratum with vemurafenib and cobimetinib treatment,³¹ 2 reports of GD with dabrafenib treatment,^27,30 and a few reports of GD with the BRAF inhibitor dabrafenib combined with the MEK inhibitor trametinib,^28,32,33 all for the treatment of metastatic melanoma. Additionally, a report described a 3-year-old boy who developed GD secondary to vemurafenib for the treatment of Langerhans cell histiocytosis.³⁴ We present a unique case of BRAF and MEK inhibitor therapy–induced GD in the treatment of metastatic cholangiocarcinoma with vemurafenib and cobimetinib.

BRAF and MEK inhibitor therapy is used in patients with metastatic melanomas with a positive BRAF V600E mutation. Due to advancements in next-generation DNA sequencing, these therapies also are being tested in clinical trials for use in the treatment of other cancers with the same checkpoint mutation, such as metastatic cholangiocarcinoma. Cutaneous reactions frequently are documented side effects that occur during treatment with BRAF and MEK inhibitors; GD is an uncommon finding. As the utilization of BRAF and MEK inhibitors increases for the treatment of a variety of other cancers, it is essential that clinicians and pathologists recognize GD as a potential cutaneous manifestation.

Atopic dermatitis (AD) and psoriasis are common skin diseases in which dysfunction of the epidermal barrier leads to skin inflammation and altered expression of proinflammatory cytokines.¹ There often is overlap in the clinical and histopathologic features of AD and psoriasis, which can make diagnosis a challenge. Persistent late-stage AD can present with psoriasiform lichenified changes, and psoriasis lesions in the acute stage can have an eczematous appearance.² Histologically, chronic psoriasis lesions share many overlapping features with AD, and some subsets of AD with IL-17 predominance (ie, intrinsic, pediatric, presentation in Asian patients) exhibit a psoriasiform appearance.^3,4

Atopic dermatitis and psoriasis are considered 2 distinct conditions because AD is a helper T cell (T_H2)–driven disease with subsequent overproduction of IL-4 and IL-13 and psoriasis is a T_H17 cell–driven disease with overproduction of IL-17³; however, the shared features of AD and psoriasis represent an underlying immunopathological spectrum^2,5,6 in which one condition can develop following treatment of the other condition (immunological shift in pathways), both conditions can occur at different times in a patient’s life with alternating cycles of disease flares, or both conditions can coexist as an overlapping syndrome.^1,2 A retrospective study from 2012 to 2019 estimated the prevalence of concomitant AD and psoriasis in the United States at 1.3%, with AD following the diagnosis of psoriasis in 67% of cases.¹ Concurrent AD and psoriasis—when both diseases flaresimultaneously—is the rarest scenario.^2,5

Treatment modalities for AD include topical corticosteroids, which act on immune cells to suppress the release of proinflammatory cytokines, as well as dupilumab, which offers targeted blockade of involved cytokines IL-4 and IL-13. Psoriasis can be treated with multiple immune modulators, including topical corticosteroids and vitamin D analogs, as well as systemic medications that reduce T-cell activation and inflammatory cytokines through targeting of IFN-γ, IL-2, tumor necrosis factor α, IL-17, and IL-23.^7,8

We present the case of a patient with long-standing concurrent, treatment-resistant AD and psoriasis who was successfully treated with dual biologic therapy with guselkumab and dupilumab.

Case Report

A 62-year-old woman presented to our dermatology clinic with red itchy scales and painful fissures on the palms, hands, and soles of more than 12 years’ duration. Her medical history included an allergy to amoxicillin-clavulanate as well as an allergy to both dog and cat dander on prick testing. Her family history included dyshidrotic eczema in her mother. A complete blood cell count with differential was within reference range. A shave biopsy of the right dorsal hand performed at the onset of symptoms at an outside facility revealed hyperkeratotic acanthotic epidermis with a mild perivascular lymphocytic infiltrate.

Results of patch testing indicated contact hypersensitivity to the botanical rosin colophonium (or colophony); carba mix (1, 3-diphenylguanidine, zinc dibutyldithiocarbamate, and zinc diethydithiocarbamate); thiuram mix (tetramethylthiuram disulfide, tetramethylthiuram monosulfide, and tetraethylthiuram disulfide); n,n-diphenylguanidine; and tixocortol-21-pivalate. Our patient was given guidance on avoiding these agents, as it was suspected that exposure may be exacerbating the psoriasis. The psoriasis was treated with topical corticosteroids, keratolytics, and calcineurin inhibitors, all of which offered minimal or no relief. Trials of systemic agents, including methotrexate (discontinued because transaminitis developed), etanercept, adalimumab, and apremilast for 6 to 10 months did not provide improvement.

Two years prior to the current presentation, our patient had been treated with the IL-23 inhibitor guselkumab, which provided moderate improvement. When she presented to our clinic, physical examination while she was taking guselkumab demonstrated prurigo with excoriations of the extremities, hyperkeratosis with scaling and fissures of the soles, erythematous scaly plaques on the palms and dorsal surface of the hands, and mild onycholysis of the nails (Figures 1 and 2). Because we were concerned about concomitant intrinsic AD, dupilumab was initiated in conjunction with guselkumab. A second biopsy was considered but deferred in favor of clinical monitoring.

After 1 year of dual biologic therapy, the patient experienced near-complete resolution of symptoms. The psoriasis completely resolved from an initial body surface area of 5%, and the AD body surface area decreased from 30% to 2% (Figure 3). The patient reported no adverse effects from treatment.

Comment

Atopic dermatitis and psoriasis involve complex immunopathology and a spectrum of cytokines that might explain the overlap in their clinical and histopathologic presentations.

Atopic dermatitis—Atopic dermatitis involves T_H1, T_H2, T_H9, T_H17, and T_H22 cells; T_H2 cells release IL-4, IL-5, and IL-13, all of which are key cytokines in the inflammatory pathway of AD.^9,10 Activation of the helper T-cell subset and the release of cytokines differ slightly based on the subcategory of AD and the stage of exacerbation. In addition to T_H2-cell activation, T_H1 cells and T_H22 cells—which release IL-12 and IL-22, respectively—are active in both intrinsic and extrinsic AD. T_H17 cells and T_H9 cells—which release IL-17 and IL-9, respectively—are more prominent in the intrinsic pathway than in the extrinsic pathway.⁹ Intrinsic AD is recognized by a lack of eosinophilia, female predominance, and delayed onset compared to extrinsic AD; there also is a lack of history of atopy.¹ Extrinsic AD is characterized by eosinophilia as well as a personal and family history of atopy.¹¹ Our patient—a female with onset in older adulthood, lack of eosinophilia, and a family history of atopy—displayed features of both intrinsic and extrinsic AD.

Psoriasis—The immunopathology of psoriasis involves stimulation of dendritic cells, which activate T_H17 cells through IL-23. T_H17 cells then release IL-17 and IL-22. Therefore, both AD and psoriasis involve activation of T_H22 and T_H1 cells, with increased IL-17 and IL-22 production.^3,10,12 IL-17 and IL-22 induce epidermal hyperplasia; IL-22 also contributes to skin barrier dysfunction.¹² Therefore, it might be reasonable to consider psoriasis and AD as diseases that exist across a T-cell axis spectrum, thereby accounting for some overlap in disease characteristics.³

Dual Biologic Therapy—Dupilumab blocks the IL-4 receptor α subunit, a receptor for IL-4 and IL-13, which are key cytokines in the pathogenesis of AD.¹⁰ Guselkumab inhibits IL-23, thus blocking the inflammatory cascade of T_H17 cell activation and release of IL-17 and IL-22 in the psoriasis pathway.¹³ Although an immunopathological spectrum exists between the 2 diseases, the continued presence of AD symptoms after blocking the IL-23 cascade suggests that additional blockade of T_H2 cells is required to control AD in patients with true concurrent disease.

Accurate diagnosis of AD and/or psoriasis is important when considering targeted treatment of these conditions with biologics. The use of dual biologics is limited by a paucity of data regarding the safety of these agents when given in combination. A recent meta-analysis of dual biologic therapy in patients with inflammatory bowel disease demonstrated acceptable safety results with a pooled adverse reaction rate of 31%.¹⁴

Anchoring Bias—Anchoring bias can occur when a clinician’s decisions are influenced by a particular event or reference point, which might cause them to disregard subsequent evidence. Our case illustrates the importance of critically assessing the response to treatment and being mindful of the potential influence of anchoring bias on the differential diagnosis. Although overcoming biases in conditions with clinical overlap can be challenging, it is important to consider coexisting AD and psoriasis in patients with extensive hand involvement when multiple treatments have failed and only a partial response to targeted pathways has been achieved. In our case, the patient also had contact hypersensitivity to tixocortol-21-pivalate, which indicates hypersensitivity to many prescription topical corticosteroids, oral prednisone, and over-the-counter hydrocortisone; however, topical corticosteroids continued to be prescribed for her, which might have contributed to the lack of improvement and even exacerbated the rash.

Future Considerations—A consideration for the future in this case is discontinuing guselkumab to observe whether symptoms recur. We discussed this option with the patient, but she opted to continue treatment with dupilumab and guselkumab because of the symptom resolution.

Conclusion

Concomitant disease can present as an overlapping pattern in the same area, whereas other regions might have geographically isolated disease. Our patient’s overlap of symptoms, the failure of multiple treatments, and the partial improvement she experienced on guselkumab made diagnosis and management challenging; however, dual biologic therapy was successful.

Atopic dermatitis (AD) and psoriasis are common skin diseases in which dysfunction of the epidermal barrier leads to skin inflammation and altered expression of proinflammatory cytokines.¹ There often is overlap in the clinical and histopathologic features of AD and psoriasis, which can make diagnosis a challenge. Persistent late-stage AD can present with psoriasiform lichenified changes, and psoriasis lesions in the acute stage can have an eczematous appearance.² Histologically, chronic psoriasis lesions share many overlapping features with AD, and some subsets of AD with IL-17 predominance (ie, intrinsic, pediatric, presentation in Asian patients) exhibit a psoriasiform appearance.^3,4

Atopic dermatitis and psoriasis are considered 2 distinct conditions because AD is a helper T cell (T_H2)–driven disease with subsequent overproduction of IL-4 and IL-13 and psoriasis is a T_H17 cell–driven disease with overproduction of IL-17³; however, the shared features of AD and psoriasis represent an underlying immunopathological spectrum^2,5,6 in which one condition can develop following treatment of the other condition (immunological shift in pathways), both conditions can occur at different times in a patient’s life with alternating cycles of disease flares, or both conditions can coexist as an overlapping syndrome.^1,2 A retrospective study from 2012 to 2019 estimated the prevalence of concomitant AD and psoriasis in the United States at 1.3%, with AD following the diagnosis of psoriasis in 67% of cases.¹ Concurrent AD and psoriasis—when both diseases flaresimultaneously—is the rarest scenario.^2,5

Treatment modalities for AD include topical corticosteroids, which act on immune cells to suppress the release of proinflammatory cytokines, as well as dupilumab, which offers targeted blockade of involved cytokines IL-4 and IL-13. Psoriasis can be treated with multiple immune modulators, including topical corticosteroids and vitamin D analogs, as well as systemic medications that reduce T-cell activation and inflammatory cytokines through targeting of IFN-γ, IL-2, tumor necrosis factor α, IL-17, and IL-23.^7,8

We present the case of a patient with long-standing concurrent, treatment-resistant AD and psoriasis who was successfully treated with dual biologic therapy with guselkumab and dupilumab.

Case Report

A 62-year-old woman presented to our dermatology clinic with red itchy scales and painful fissures on the palms, hands, and soles of more than 12 years’ duration. Her medical history included an allergy to amoxicillin-clavulanate as well as an allergy to both dog and cat dander on prick testing. Her family history included dyshidrotic eczema in her mother. A complete blood cell count with differential was within reference range. A shave biopsy of the right dorsal hand performed at the onset of symptoms at an outside facility revealed hyperkeratotic acanthotic epidermis with a mild perivascular lymphocytic infiltrate.

Results of patch testing indicated contact hypersensitivity to the botanical rosin colophonium (or colophony); carba mix (1, 3-diphenylguanidine, zinc dibutyldithiocarbamate, and zinc diethydithiocarbamate); thiuram mix (tetramethylthiuram disulfide, tetramethylthiuram monosulfide, and tetraethylthiuram disulfide); n,n-diphenylguanidine; and tixocortol-21-pivalate. Our patient was given guidance on avoiding these agents, as it was suspected that exposure may be exacerbating the psoriasis. The psoriasis was treated with topical corticosteroids, keratolytics, and calcineurin inhibitors, all of which offered minimal or no relief. Trials of systemic agents, including methotrexate (discontinued because transaminitis developed), etanercept, adalimumab, and apremilast for 6 to 10 months did not provide improvement.

Two years prior to the current presentation, our patient had been treated with the IL-23 inhibitor guselkumab, which provided moderate improvement. When she presented to our clinic, physical examination while she was taking guselkumab demonstrated prurigo with excoriations of the extremities, hyperkeratosis with scaling and fissures of the soles, erythematous scaly plaques on the palms and dorsal surface of the hands, and mild onycholysis of the nails (Figures 1 and 2). Because we were concerned about concomitant intrinsic AD, dupilumab was initiated in conjunction with guselkumab. A second biopsy was considered but deferred in favor of clinical monitoring.

After 1 year of dual biologic therapy, the patient experienced near-complete resolution of symptoms. The psoriasis completely resolved from an initial body surface area of 5%, and the AD body surface area decreased from 30% to 2% (Figure 3). The patient reported no adverse effects from treatment.

Comment

Atopic dermatitis and psoriasis involve complex immunopathology and a spectrum of cytokines that might explain the overlap in their clinical and histopathologic presentations.

Atopic dermatitis—Atopic dermatitis involves T_H1, T_H2, T_H9, T_H17, and T_H22 cells; T_H2 cells release IL-4, IL-5, and IL-13, all of which are key cytokines in the inflammatory pathway of AD.^9,10 Activation of the helper T-cell subset and the release of cytokines differ slightly based on the subcategory of AD and the stage of exacerbation. In addition to T_H2-cell activation, T_H1 cells and T_H22 cells—which release IL-12 and IL-22, respectively—are active in both intrinsic and extrinsic AD. T_H17 cells and T_H9 cells—which release IL-17 and IL-9, respectively—are more prominent in the intrinsic pathway than in the extrinsic pathway.⁹ Intrinsic AD is recognized by a lack of eosinophilia, female predominance, and delayed onset compared to extrinsic AD; there also is a lack of history of atopy.¹ Extrinsic AD is characterized by eosinophilia as well as a personal and family history of atopy.¹¹ Our patient—a female with onset in older adulthood, lack of eosinophilia, and a family history of atopy—displayed features of both intrinsic and extrinsic AD.

Psoriasis—The immunopathology of psoriasis involves stimulation of dendritic cells, which activate T_H17 cells through IL-23. T_H17 cells then release IL-17 and IL-22. Therefore, both AD and psoriasis involve activation of T_H22 and T_H1 cells, with increased IL-17 and IL-22 production.^3,10,12 IL-17 and IL-22 induce epidermal hyperplasia; IL-22 also contributes to skin barrier dysfunction.¹² Therefore, it might be reasonable to consider psoriasis and AD as diseases that exist across a T-cell axis spectrum, thereby accounting for some overlap in disease characteristics.³

Dual Biologic Therapy—Dupilumab blocks the IL-4 receptor α subunit, a receptor for IL-4 and IL-13, which are key cytokines in the pathogenesis of AD.¹⁰ Guselkumab inhibits IL-23, thus blocking the inflammatory cascade of T_H17 cell activation and release of IL-17 and IL-22 in the psoriasis pathway.¹³ Although an immunopathological spectrum exists between the 2 diseases, the continued presence of AD symptoms after blocking the IL-23 cascade suggests that additional blockade of T_H2 cells is required to control AD in patients with true concurrent disease.

Accurate diagnosis of AD and/or psoriasis is important when considering targeted treatment of these conditions with biologics. The use of dual biologics is limited by a paucity of data regarding the safety of these agents when given in combination. A recent meta-analysis of dual biologic therapy in patients with inflammatory bowel disease demonstrated acceptable safety results with a pooled adverse reaction rate of 31%.¹⁴

Anchoring Bias—Anchoring bias can occur when a clinician’s decisions are influenced by a particular event or reference point, which might cause them to disregard subsequent evidence. Our case illustrates the importance of critically assessing the response to treatment and being mindful of the potential influence of anchoring bias on the differential diagnosis. Although overcoming biases in conditions with clinical overlap can be challenging, it is important to consider coexisting AD and psoriasis in patients with extensive hand involvement when multiple treatments have failed and only a partial response to targeted pathways has been achieved. In our case, the patient also had contact hypersensitivity to tixocortol-21-pivalate, which indicates hypersensitivity to many prescription topical corticosteroids, oral prednisone, and over-the-counter hydrocortisone; however, topical corticosteroids continued to be prescribed for her, which might have contributed to the lack of improvement and even exacerbated the rash.

Future Considerations—A consideration for the future in this case is discontinuing guselkumab to observe whether symptoms recur. We discussed this option with the patient, but she opted to continue treatment with dupilumab and guselkumab because of the symptom resolution.

Conclusion

Concomitant disease can present as an overlapping pattern in the same area, whereas other regions might have geographically isolated disease. Our patient’s overlap of symptoms, the failure of multiple treatments, and the partial improvement she experienced on guselkumab made diagnosis and management challenging; however, dual biologic therapy was successful.

Atopic dermatitis (AD) and psoriasis are common skin diseases in which dysfunction of the epidermal barrier leads to skin inflammation and altered expression of proinflammatory cytokines.¹ There often is overlap in the clinical and histopathologic features of AD and psoriasis, which can make diagnosis a challenge. Persistent late-stage AD can present with psoriasiform lichenified changes, and psoriasis lesions in the acute stage can have an eczematous appearance.² Histologically, chronic psoriasis lesions share many overlapping features with AD, and some subsets of AD with IL-17 predominance (ie, intrinsic, pediatric, presentation in Asian patients) exhibit a psoriasiform appearance.^3,4

Atopic dermatitis and psoriasis are considered 2 distinct conditions because AD is a helper T cell (T_H2)–driven disease with subsequent overproduction of IL-4 and IL-13 and psoriasis is a T_H17 cell–driven disease with overproduction of IL-17³; however, the shared features of AD and psoriasis represent an underlying immunopathological spectrum^2,5,6 in which one condition can develop following treatment of the other condition (immunological shift in pathways), both conditions can occur at different times in a patient’s life with alternating cycles of disease flares, or both conditions can coexist as an overlapping syndrome.^1,2 A retrospective study from 2012 to 2019 estimated the prevalence of concomitant AD and psoriasis in the United States at 1.3%, with AD following the diagnosis of psoriasis in 67% of cases.¹ Concurrent AD and psoriasis—when both diseases flaresimultaneously—is the rarest scenario.^2,5

Treatment modalities for AD include topical corticosteroids, which act on immune cells to suppress the release of proinflammatory cytokines, as well as dupilumab, which offers targeted blockade of involved cytokines IL-4 and IL-13. Psoriasis can be treated with multiple immune modulators, including topical corticosteroids and vitamin D analogs, as well as systemic medications that reduce T-cell activation and inflammatory cytokines through targeting of IFN-γ, IL-2, tumor necrosis factor α, IL-17, and IL-23.^7,8

We present the case of a patient with long-standing concurrent, treatment-resistant AD and psoriasis who was successfully treated with dual biologic therapy with guselkumab and dupilumab.

Case Report

A 62-year-old woman presented to our dermatology clinic with red itchy scales and painful fissures on the palms, hands, and soles of more than 12 years’ duration. Her medical history included an allergy to amoxicillin-clavulanate as well as an allergy to both dog and cat dander on prick testing. Her family history included dyshidrotic eczema in her mother. A complete blood cell count with differential was within reference range. A shave biopsy of the right dorsal hand performed at the onset of symptoms at an outside facility revealed hyperkeratotic acanthotic epidermis with a mild perivascular lymphocytic infiltrate.

Results of patch testing indicated contact hypersensitivity to the botanical rosin colophonium (or colophony); carba mix (1, 3-diphenylguanidine, zinc dibutyldithiocarbamate, and zinc diethydithiocarbamate); thiuram mix (tetramethylthiuram disulfide, tetramethylthiuram monosulfide, and tetraethylthiuram disulfide); n,n-diphenylguanidine; and tixocortol-21-pivalate. Our patient was given guidance on avoiding these agents, as it was suspected that exposure may be exacerbating the psoriasis. The psoriasis was treated with topical corticosteroids, keratolytics, and calcineurin inhibitors, all of which offered minimal or no relief. Trials of systemic agents, including methotrexate (discontinued because transaminitis developed), etanercept, adalimumab, and apremilast for 6 to 10 months did not provide improvement.

Two years prior to the current presentation, our patient had been treated with the IL-23 inhibitor guselkumab, which provided moderate improvement. When she presented to our clinic, physical examination while she was taking guselkumab demonstrated prurigo with excoriations of the extremities, hyperkeratosis with scaling and fissures of the soles, erythematous scaly plaques on the palms and dorsal surface of the hands, and mild onycholysis of the nails (Figures 1 and 2). Because we were concerned about concomitant intrinsic AD, dupilumab was initiated in conjunction with guselkumab. A second biopsy was considered but deferred in favor of clinical monitoring.

After 1 year of dual biologic therapy, the patient experienced near-complete resolution of symptoms. The psoriasis completely resolved from an initial body surface area of 5%, and the AD body surface area decreased from 30% to 2% (Figure 3). The patient reported no adverse effects from treatment.

Comment

Atopic dermatitis and psoriasis involve complex immunopathology and a spectrum of cytokines that might explain the overlap in their clinical and histopathologic presentations.

Atopic dermatitis—Atopic dermatitis involves T_H1, T_H2, T_H9, T_H17, and T_H22 cells; T_H2 cells release IL-4, IL-5, and IL-13, all of which are key cytokines in the inflammatory pathway of AD.^9,10 Activation of the helper T-cell subset and the release of cytokines differ slightly based on the subcategory of AD and the stage of exacerbation. In addition to T_H2-cell activation, T_H1 cells and T_H22 cells—which release IL-12 and IL-22, respectively—are active in both intrinsic and extrinsic AD. T_H17 cells and T_H9 cells—which release IL-17 and IL-9, respectively—are more prominent in the intrinsic pathway than in the extrinsic pathway.⁹ Intrinsic AD is recognized by a lack of eosinophilia, female predominance, and delayed onset compared to extrinsic AD; there also is a lack of history of atopy.¹ Extrinsic AD is characterized by eosinophilia as well as a personal and family history of atopy.¹¹ Our patient—a female with onset in older adulthood, lack of eosinophilia, and a family history of atopy—displayed features of both intrinsic and extrinsic AD.

Psoriasis—The immunopathology of psoriasis involves stimulation of dendritic cells, which activate T_H17 cells through IL-23. T_H17 cells then release IL-17 and IL-22. Therefore, both AD and psoriasis involve activation of T_H22 and T_H1 cells, with increased IL-17 and IL-22 production.^3,10,12 IL-17 and IL-22 induce epidermal hyperplasia; IL-22 also contributes to skin barrier dysfunction.¹² Therefore, it might be reasonable to consider psoriasis and AD as diseases that exist across a T-cell axis spectrum, thereby accounting for some overlap in disease characteristics.³

Dual Biologic Therapy—Dupilumab blocks the IL-4 receptor α subunit, a receptor for IL-4 and IL-13, which are key cytokines in the pathogenesis of AD.¹⁰ Guselkumab inhibits IL-23, thus blocking the inflammatory cascade of T_H17 cell activation and release of IL-17 and IL-22 in the psoriasis pathway.¹³ Although an immunopathological spectrum exists between the 2 diseases, the continued presence of AD symptoms after blocking the IL-23 cascade suggests that additional blockade of T_H2 cells is required to control AD in patients with true concurrent disease.

Accurate diagnosis of AD and/or psoriasis is important when considering targeted treatment of these conditions with biologics. The use of dual biologics is limited by a paucity of data regarding the safety of these agents when given in combination. A recent meta-analysis of dual biologic therapy in patients with inflammatory bowel disease demonstrated acceptable safety results with a pooled adverse reaction rate of 31%.¹⁴

Anchoring Bias—Anchoring bias can occur when a clinician’s decisions are influenced by a particular event or reference point, which might cause them to disregard subsequent evidence. Our case illustrates the importance of critically assessing the response to treatment and being mindful of the potential influence of anchoring bias on the differential diagnosis. Although overcoming biases in conditions with clinical overlap can be challenging, it is important to consider coexisting AD and psoriasis in patients with extensive hand involvement when multiple treatments have failed and only a partial response to targeted pathways has been achieved. In our case, the patient also had contact hypersensitivity to tixocortol-21-pivalate, which indicates hypersensitivity to many prescription topical corticosteroids, oral prednisone, and over-the-counter hydrocortisone; however, topical corticosteroids continued to be prescribed for her, which might have contributed to the lack of improvement and even exacerbated the rash.

Future Considerations—A consideration for the future in this case is discontinuing guselkumab to observe whether symptoms recur. We discussed this option with the patient, but she opted to continue treatment with dupilumab and guselkumab because of the symptom resolution.

Conclusion

Concomitant disease can present as an overlapping pattern in the same area, whereas other regions might have geographically isolated disease. Our patient’s overlap of symptoms, the failure of multiple treatments, and the partial improvement she experienced on guselkumab made diagnosis and management challenging; however, dual biologic therapy was successful.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands. These neoplasms share many histologic features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC,¹ which is analogous to ductal carcinoma in situ and mucinous carcinoma of the breast, respectively.^2-5 Management involves a metastatic workup and either wide local excision (WLE) with margins greater than 5 mm or Mohs micrographic surgery (MMS) in anatomically sensitive areas.² We present 2 cases of EMPSGC and 3 cases of PCMC. We also review the clinical and histopathological features, differential diagnoses, and treatments.

Methods

Following institutional review board approval, we conducted a retrospective, single-institution case series. We searched electronic medical records dating from 2000 to 2019 for tumors diagnosed as PCMC or extramammary Paget disease treated with MMS. We gathered demographic, clinical, pathologic, and follow-up information from the electronic medical records for each case (Tables 1 and 2). Two dermatopathologists (B.P. and B.F.K.) reviewed the hematoxylin and eosin–stained slides of each tumor as well as all available immunohistochemical stains. One of the reviewers (B.F.K.) is a board-certified dermatologist, dermatopathologist, and fellowship-trained Mohs surgeon.

Results

Demographic and Clinical Information—We identified 2 cases of EMPSGC and 3 cases of PCMC diagnosed and treated at our institution; 4 of these cases had been treated within the last 2 years. One had been treated 18 years prior; case information was limited due to planned institutional record destruction. Three of the patients were female and 2 were male. The mean age at presentation was 71 years (range, 62–87 years). None had experienced recurrence or metastases after a mean follow-up of 30 months.

Case 1—A 68-year-old woman noted a slow-growing, flesh-colored papule measuring 12×10 mm on the right lower eyelid. An excisional biopsy was completed with 2-mm clinical margins, and the defect was closed in a linear fashion. Histologic sections demonstrated EMPSGC with uninvolved margins. The patient desired no further intervention and was clinically followed. Magnetic resonance imaging (MRI) of the head and neck found no evidence of metastasis. She has had no recurrence after 15 months.

Case 2—A 62-year-old man presented with a 7×5-mm, flesh-colored papule on the left lower eyelid margin (Figure 1). It was previously treated conservatively as a hordeolum but was biopsied after it failed to resolve with 3-mm margins. Histopathology demonstrated an EMPSGC (Figure 2). The lesion was treated with modified MMS with permanent en face section processing and cleared after 1 stage. Computed tomography of the head and neck showed no abnormalities. He has had no recurrence after 9 months.

Case 3—A 72-year-old man presented with a nontender papule near the right lateral canthus. A punch biopsy demonstrated PCMC. He was treated via modified MMS with permanent en face section processing. The tumor was cleared in 1 stage. He showed no evidence of recurrence after 112 months and died of unrelated causes. The rest of his clinical information was limited because of planned institutional destruction of records.

Case 4—An 87-year-old woman presented with a 25×25-mm, slow-growing mass of 12 months’ duration on the left lower abdomen (Figure 3). A biopsy demonstrated PCMC (Figure 4). Because of the size of the lesion, she underwent WLE with 20- to 30-mm margins by a general surgeon under general anesthesia. Positron emission tomography/computed tomography was unremarkable. She has remained disease free for 11 months.

Case 5—A 66-year-old woman presented for evaluation of a posterior scalp mass measuring 23×18 mm that had grown over the last 24 months. Biopsy showed mucinous carcinoma with lymphovascular invasion consistent with PCMC (Figure 5) confirmed on multiple tissue levels and with the aid of immunohistochemistry. She was sent for an MRI of the head, neck, chest, abdomen, and pelvis, which demonstrated 2 enlarged postauricular lymph nodes and raised suspicion for metastatic disease vs reactive lymphadenopathy. Mohs micrographic surgery with frozen sections was performed with 1- to 3-mm margins; the final layer was sent for permanent processing and confirmed negative margins. Sentinel lymph node biopsy and lymphadenectomy of the 2 nodes present on imaging showed no evidence of metastasis. The patient had no recurrence in 1 month.

Comment

Endocrine mucin-producing sweat gland carcinoma and PCMC are sweat gland malignancies that carry low metastatic potential but are locally aggressive. Endocrine mucin-producing sweat gland carcinoma has a strong predilection for the periorbital region, especially the lower eyelids of older women.³ Primary cutaneous mucinous carcinoma may arise on the eyelids, scalp, axillae, and trunk and has been reported more often in older men. These slow-growing tumors appear as nonspecific nodules.³ Lesions frequently are asymptomatic but rarely may cause pruritus and bleeding. Histologically, EMPSGC appears as solid or cystic nodules of cells with a papillary, cribriform, or pseudopapillary appearance. Intracellular or extracellular mucin as well as malignant spread of tumor cells along pre-existing ductlike structures make it difficult to histologically distinguish EMPSGC from ductal carcinoma in situ.³

A key histopathologic feature of PCMC is basophilic epithelioid cell nests in mucinous lakes.⁴ Rosettelike structures are seen within solid areas of the tumor. Fibrous septae separate individual collections of mucin, creating a lobulated appearance. The histopathologic differential diagnosis of EMPSGC and PCMC is broad, including basal cell carcinoma, hidradenoma, hidradenocarcinoma, apocrine adenoma, and dermal duct tumor. Positive expression of at least 1 neuroendocrine marker (ie, synaptophysin, neuron-specific enolase, chromogranin) and low-molecular cytokeratin (cytokeratin 7, CAM5.2, Ber-EP4) can aid in the diagnosis of both EMPSGC and PCMC.⁴ The use of p63 immunostaining is beneficial in delineating adnexal neoplasms. Adnexal tumors that stain positively with p63 are more likely to be of primary cutaneous origin, whereas lack of p63 staining usually denotes a secondary metastatic process. However, p63 staining is less reliable when distinguishing primary and metastatic mucinous neoplasms. Metastatic mucinous carcinomas often stain positive with p63, while PCMC usually stains negative despite its primary cutaneous origin, decreasing the clinical utility of p63. The tumor may be identical to metastatic mucinous adenocarcinoma of the breast, gastrointestinal tract, lung, ovary, and pancreas. Tumor islands floating in mucin are identified in both primary cutaneous and metastatic disease to the skin.^3,6 Areas of tumor necrosis, notable atypia, and perineural or lymphovascular invasion are infrequently reported in EMPSGC or PCMC, though lymphatic invasion was identified in case 5 presented herein.

A metastatic workup is warranted in all cases of PCMC, including a thorough history, review of systems, breast examination, and imaging. A workup may be considered in cases of EMPSGC depending on histologic features or clinical history.

There is uncertainty regarding the optimal management of these slow-growing yet locally destructive tumors.⁵ The incidence of local recurrence of PCMC after WLE with narrow margins of at least 1 cm can be as high as 30% to 40%, especially on the eyelid.⁴ There is no consensus on surgical care for either of these tumors.⁵ Because of the high recurrence rate and the predilection for the eyelid and face, MMS provides an excellent alternative to WLE for tissue preservation and meticulous margin control. We advocate for the use of the Mohs technique with permanent sectioning, which may delay the repair, but reviewing tissue with permanent fixation improves the quality and accuracy of the margin evaluation because these tumors often are infiltrative and difficult to delineate under frozen section processing. Permanent en face sectioning allows the laboratory to utilize the full array of immunohistochemical stains for these tumors, providing accurate and timely results.

Limitations to our retrospective uncontrolled study include missing or incomplete data points and short follow-up time. Additionally, there was no standardization to the margins removed with MMS or WLE because of the limited available data that comment on appropriate margins.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands. These neoplasms share many histologic features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC,¹ which is analogous to ductal carcinoma in situ and mucinous carcinoma of the breast, respectively.^2-5 Management involves a metastatic workup and either wide local excision (WLE) with margins greater than 5 mm or Mohs micrographic surgery (MMS) in anatomically sensitive areas.² We present 2 cases of EMPSGC and 3 cases of PCMC. We also review the clinical and histopathological features, differential diagnoses, and treatments.

Methods

Following institutional review board approval, we conducted a retrospective, single-institution case series. We searched electronic medical records dating from 2000 to 2019 for tumors diagnosed as PCMC or extramammary Paget disease treated with MMS. We gathered demographic, clinical, pathologic, and follow-up information from the electronic medical records for each case (Tables 1 and 2). Two dermatopathologists (B.P. and B.F.K.) reviewed the hematoxylin and eosin–stained slides of each tumor as well as all available immunohistochemical stains. One of the reviewers (B.F.K.) is a board-certified dermatologist, dermatopathologist, and fellowship-trained Mohs surgeon.

Results

Demographic and Clinical Information—We identified 2 cases of EMPSGC and 3 cases of PCMC diagnosed and treated at our institution; 4 of these cases had been treated within the last 2 years. One had been treated 18 years prior; case information was limited due to planned institutional record destruction. Three of the patients were female and 2 were male. The mean age at presentation was 71 years (range, 62–87 years). None had experienced recurrence or metastases after a mean follow-up of 30 months.

Case 1—A 68-year-old woman noted a slow-growing, flesh-colored papule measuring 12×10 mm on the right lower eyelid. An excisional biopsy was completed with 2-mm clinical margins, and the defect was closed in a linear fashion. Histologic sections demonstrated EMPSGC with uninvolved margins. The patient desired no further intervention and was clinically followed. Magnetic resonance imaging (MRI) of the head and neck found no evidence of metastasis. She has had no recurrence after 15 months.

Case 2—A 62-year-old man presented with a 7×5-mm, flesh-colored papule on the left lower eyelid margin (Figure 1). It was previously treated conservatively as a hordeolum but was biopsied after it failed to resolve with 3-mm margins. Histopathology demonstrated an EMPSGC (Figure 2). The lesion was treated with modified MMS with permanent en face section processing and cleared after 1 stage. Computed tomography of the head and neck showed no abnormalities. He has had no recurrence after 9 months.

Case 3—A 72-year-old man presented with a nontender papule near the right lateral canthus. A punch biopsy demonstrated PCMC. He was treated via modified MMS with permanent en face section processing. The tumor was cleared in 1 stage. He showed no evidence of recurrence after 112 months and died of unrelated causes. The rest of his clinical information was limited because of planned institutional destruction of records.

Case 4—An 87-year-old woman presented with a 25×25-mm, slow-growing mass of 12 months’ duration on the left lower abdomen (Figure 3). A biopsy demonstrated PCMC (Figure 4). Because of the size of the lesion, she underwent WLE with 20- to 30-mm margins by a general surgeon under general anesthesia. Positron emission tomography/computed tomography was unremarkable. She has remained disease free for 11 months.

Case 5—A 66-year-old woman presented for evaluation of a posterior scalp mass measuring 23×18 mm that had grown over the last 24 months. Biopsy showed mucinous carcinoma with lymphovascular invasion consistent with PCMC (Figure 5) confirmed on multiple tissue levels and with the aid of immunohistochemistry. She was sent for an MRI of the head, neck, chest, abdomen, and pelvis, which demonstrated 2 enlarged postauricular lymph nodes and raised suspicion for metastatic disease vs reactive lymphadenopathy. Mohs micrographic surgery with frozen sections was performed with 1- to 3-mm margins; the final layer was sent for permanent processing and confirmed negative margins. Sentinel lymph node biopsy and lymphadenectomy of the 2 nodes present on imaging showed no evidence of metastasis. The patient had no recurrence in 1 month.

Comment

Endocrine mucin-producing sweat gland carcinoma and PCMC are sweat gland malignancies that carry low metastatic potential but are locally aggressive. Endocrine mucin-producing sweat gland carcinoma has a strong predilection for the periorbital region, especially the lower eyelids of older women.³ Primary cutaneous mucinous carcinoma may arise on the eyelids, scalp, axillae, and trunk and has been reported more often in older men. These slow-growing tumors appear as nonspecific nodules.³ Lesions frequently are asymptomatic but rarely may cause pruritus and bleeding. Histologically, EMPSGC appears as solid or cystic nodules of cells with a papillary, cribriform, or pseudopapillary appearance. Intracellular or extracellular mucin as well as malignant spread of tumor cells along pre-existing ductlike structures make it difficult to histologically distinguish EMPSGC from ductal carcinoma in situ.³

A key histopathologic feature of PCMC is basophilic epithelioid cell nests in mucinous lakes.⁴ Rosettelike structures are seen within solid areas of the tumor. Fibrous septae separate individual collections of mucin, creating a lobulated appearance. The histopathologic differential diagnosis of EMPSGC and PCMC is broad, including basal cell carcinoma, hidradenoma, hidradenocarcinoma, apocrine adenoma, and dermal duct tumor. Positive expression of at least 1 neuroendocrine marker (ie, synaptophysin, neuron-specific enolase, chromogranin) and low-molecular cytokeratin (cytokeratin 7, CAM5.2, Ber-EP4) can aid in the diagnosis of both EMPSGC and PCMC.⁴ The use of p63 immunostaining is beneficial in delineating adnexal neoplasms. Adnexal tumors that stain positively with p63 are more likely to be of primary cutaneous origin, whereas lack of p63 staining usually denotes a secondary metastatic process. However, p63 staining is less reliable when distinguishing primary and metastatic mucinous neoplasms. Metastatic mucinous carcinomas often stain positive with p63, while PCMC usually stains negative despite its primary cutaneous origin, decreasing the clinical utility of p63. The tumor may be identical to metastatic mucinous adenocarcinoma of the breast, gastrointestinal tract, lung, ovary, and pancreas. Tumor islands floating in mucin are identified in both primary cutaneous and metastatic disease to the skin.^3,6 Areas of tumor necrosis, notable atypia, and perineural or lymphovascular invasion are infrequently reported in EMPSGC or PCMC, though lymphatic invasion was identified in case 5 presented herein.

A metastatic workup is warranted in all cases of PCMC, including a thorough history, review of systems, breast examination, and imaging. A workup may be considered in cases of EMPSGC depending on histologic features or clinical history.

There is uncertainty regarding the optimal management of these slow-growing yet locally destructive tumors.⁵ The incidence of local recurrence of PCMC after WLE with narrow margins of at least 1 cm can be as high as 30% to 40%, especially on the eyelid.⁴ There is no consensus on surgical care for either of these tumors.⁵ Because of the high recurrence rate and the predilection for the eyelid and face, MMS provides an excellent alternative to WLE for tissue preservation and meticulous margin control. We advocate for the use of the Mohs technique with permanent sectioning, which may delay the repair, but reviewing tissue with permanent fixation improves the quality and accuracy of the margin evaluation because these tumors often are infiltrative and difficult to delineate under frozen section processing. Permanent en face sectioning allows the laboratory to utilize the full array of immunohistochemical stains for these tumors, providing accurate and timely results.

Limitations to our retrospective uncontrolled study include missing or incomplete data points and short follow-up time. Additionally, there was no standardization to the margins removed with MMS or WLE because of the limited available data that comment on appropriate margins.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands. These neoplasms share many histologic features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC,¹ which is analogous to ductal carcinoma in situ and mucinous carcinoma of the breast, respectively.^2-5 Management involves a metastatic workup and either wide local excision (WLE) with margins greater than 5 mm or Mohs micrographic surgery (MMS) in anatomically sensitive areas.² We present 2 cases of EMPSGC and 3 cases of PCMC. We also review the clinical and histopathological features, differential diagnoses, and treatments.

Methods

Following institutional review board approval, we conducted a retrospective, single-institution case series. We searched electronic medical records dating from 2000 to 2019 for tumors diagnosed as PCMC or extramammary Paget disease treated with MMS. We gathered demographic, clinical, pathologic, and follow-up information from the electronic medical records for each case (Tables 1 and 2). Two dermatopathologists (B.P. and B.F.K.) reviewed the hematoxylin and eosin–stained slides of each tumor as well as all available immunohistochemical stains. One of the reviewers (B.F.K.) is a board-certified dermatologist, dermatopathologist, and fellowship-trained Mohs surgeon.

Results

Demographic and Clinical Information—We identified 2 cases of EMPSGC and 3 cases of PCMC diagnosed and treated at our institution; 4 of these cases had been treated within the last 2 years. One had been treated 18 years prior; case information was limited due to planned institutional record destruction. Three of the patients were female and 2 were male. The mean age at presentation was 71 years (range, 62–87 years). None had experienced recurrence or metastases after a mean follow-up of 30 months.

Case 1—A 68-year-old woman noted a slow-growing, flesh-colored papule measuring 12×10 mm on the right lower eyelid. An excisional biopsy was completed with 2-mm clinical margins, and the defect was closed in a linear fashion. Histologic sections demonstrated EMPSGC with uninvolved margins. The patient desired no further intervention and was clinically followed. Magnetic resonance imaging (MRI) of the head and neck found no evidence of metastasis. She has had no recurrence after 15 months.

Case 2—A 62-year-old man presented with a 7×5-mm, flesh-colored papule on the left lower eyelid margin (Figure 1). It was previously treated conservatively as a hordeolum but was biopsied after it failed to resolve with 3-mm margins. Histopathology demonstrated an EMPSGC (Figure 2). The lesion was treated with modified MMS with permanent en face section processing and cleared after 1 stage. Computed tomography of the head and neck showed no abnormalities. He has had no recurrence after 9 months.

Case 3—A 72-year-old man presented with a nontender papule near the right lateral canthus. A punch biopsy demonstrated PCMC. He was treated via modified MMS with permanent en face section processing. The tumor was cleared in 1 stage. He showed no evidence of recurrence after 112 months and died of unrelated causes. The rest of his clinical information was limited because of planned institutional destruction of records.

Case 4—An 87-year-old woman presented with a 25×25-mm, slow-growing mass of 12 months’ duration on the left lower abdomen (Figure 3). A biopsy demonstrated PCMC (Figure 4). Because of the size of the lesion, she underwent WLE with 20- to 30-mm margins by a general surgeon under general anesthesia. Positron emission tomography/computed tomography was unremarkable. She has remained disease free for 11 months.

Case 5—A 66-year-old woman presented for evaluation of a posterior scalp mass measuring 23×18 mm that had grown over the last 24 months. Biopsy showed mucinous carcinoma with lymphovascular invasion consistent with PCMC (Figure 5) confirmed on multiple tissue levels and with the aid of immunohistochemistry. She was sent for an MRI of the head, neck, chest, abdomen, and pelvis, which demonstrated 2 enlarged postauricular lymph nodes and raised suspicion for metastatic disease vs reactive lymphadenopathy. Mohs micrographic surgery with frozen sections was performed with 1- to 3-mm margins; the final layer was sent for permanent processing and confirmed negative margins. Sentinel lymph node biopsy and lymphadenectomy of the 2 nodes present on imaging showed no evidence of metastasis. The patient had no recurrence in 1 month.

Comment

Endocrine mucin-producing sweat gland carcinoma and PCMC are sweat gland malignancies that carry low metastatic potential but are locally aggressive. Endocrine mucin-producing sweat gland carcinoma has a strong predilection for the periorbital region, especially the lower eyelids of older women.³ Primary cutaneous mucinous carcinoma may arise on the eyelids, scalp, axillae, and trunk and has been reported more often in older men. These slow-growing tumors appear as nonspecific nodules.³ Lesions frequently are asymptomatic but rarely may cause pruritus and bleeding. Histologically, EMPSGC appears as solid or cystic nodules of cells with a papillary, cribriform, or pseudopapillary appearance. Intracellular or extracellular mucin as well as malignant spread of tumor cells along pre-existing ductlike structures make it difficult to histologically distinguish EMPSGC from ductal carcinoma in situ.³

A key histopathologic feature of PCMC is basophilic epithelioid cell nests in mucinous lakes.⁴ Rosettelike structures are seen within solid areas of the tumor. Fibrous septae separate individual collections of mucin, creating a lobulated appearance. The histopathologic differential diagnosis of EMPSGC and PCMC is broad, including basal cell carcinoma, hidradenoma, hidradenocarcinoma, apocrine adenoma, and dermal duct tumor. Positive expression of at least 1 neuroendocrine marker (ie, synaptophysin, neuron-specific enolase, chromogranin) and low-molecular cytokeratin (cytokeratin 7, CAM5.2, Ber-EP4) can aid in the diagnosis of both EMPSGC and PCMC.⁴ The use of p63 immunostaining is beneficial in delineating adnexal neoplasms. Adnexal tumors that stain positively with p63 are more likely to be of primary cutaneous origin, whereas lack of p63 staining usually denotes a secondary metastatic process. However, p63 staining is less reliable when distinguishing primary and metastatic mucinous neoplasms. Metastatic mucinous carcinomas often stain positive with p63, while PCMC usually stains negative despite its primary cutaneous origin, decreasing the clinical utility of p63. The tumor may be identical to metastatic mucinous adenocarcinoma of the breast, gastrointestinal tract, lung, ovary, and pancreas. Tumor islands floating in mucin are identified in both primary cutaneous and metastatic disease to the skin.^3,6 Areas of tumor necrosis, notable atypia, and perineural or lymphovascular invasion are infrequently reported in EMPSGC or PCMC, though lymphatic invasion was identified in case 5 presented herein.

A metastatic workup is warranted in all cases of PCMC, including a thorough history, review of systems, breast examination, and imaging. A workup may be considered in cases of EMPSGC depending on histologic features or clinical history.

There is uncertainty regarding the optimal management of these slow-growing yet locally destructive tumors.⁵ The incidence of local recurrence of PCMC after WLE with narrow margins of at least 1 cm can be as high as 30% to 40%, especially on the eyelid.⁴ There is no consensus on surgical care for either of these tumors.⁵ Because of the high recurrence rate and the predilection for the eyelid and face, MMS provides an excellent alternative to WLE for tissue preservation and meticulous margin control. We advocate for the use of the Mohs technique with permanent sectioning, which may delay the repair, but reviewing tissue with permanent fixation improves the quality and accuracy of the margin evaluation because these tumors often are infiltrative and difficult to delineate under frozen section processing. Permanent en face sectioning allows the laboratory to utilize the full array of immunohistochemical stains for these tumors, providing accurate and timely results.

Limitations to our retrospective uncontrolled study include missing or incomplete data points and short follow-up time. Additionally, there was no standardization to the margins removed with MMS or WLE because of the limited available data that comment on appropriate margins.

To the Editor:

Cat scratch disease (CSD) is caused by Bartonella henselae and Bartonella clarridgeiae bacteria transferred from cats to humans that results in an inflamed inoculation site and tender lymphadenopathy. Pityriasis rosea (PR) and PR-like eruptions are self-limited, acute exanthems that have been associated with infections, vaccinations, and medications. We report a case of PR occurring in a 10-year-old girl with CSD, which may suggest an association between the 2 diseases.

A 10-year-old girl who was otherwise healthy presented in the winter with a rash of 5 days’ duration. Fourteen days prior to the rash, the patient reported being scratched by a new kitten and noted a pinpoint “puncture” on the left forearm that developed into a red papule over the following week. Seven days after the cat scratch, the patient experienced pain and swelling in the left axilla. Approximately 1 week after the onset of lymphadenopathy, the patient developed an asymptomatic rash that started with a large spot on the left chest, followed by smaller spots appearing over the next 2 days and spreading to the rest of the trunk. Four days after the rash onset, the patient experienced a mild headache, low-grade subjective fever, and chills. She denied any recent travel, bug bites, sore throat, and diarrhea. She was up-to-date on all vaccinations and had not received any vaccines preceding the symptoms. Physical examination revealed a 2-cm pink, scaly, thin plaque with a collarette of scale on the left upper chest (herald patch), along with multiple thin pink papules and small plaques with central scale on the trunk (Figure 1). A pustule with adjacent linear erosion was present on the left ventral forearm (Figure 2). The patient had a tender subcutaneous nodule in the left axilla as well as bilateral anterior and posterior cervical-chain subcutaneous tender nodules. There was no involvement of the palms, soles, or mucosae.

The patient was empirically treated for CSD with azithromycin (200 mg/5 mL), 404 mg on day 1 followed by 202 mg daily for 4 days. The rash was treated with hydrocortisone cream 2.5% twice daily for 2 weeks. A wound culture of the pustule on the left forearm was negative for neutrophils and organisms. Antibody serologies obtained 4 weeks after presentation were notable for an elevated B henselae IgG titer of 1:640, confirming the diagnosis of CSD. Following treatment with azithromycin and hydrocortisone, all of the patient’s symptoms resolved after 1 to 2 weeks.

Cat scratch disease is a zoonotic infection caused by the bacteria B henselae and the more recently described pathogen B clarridgeiae. Cat fleas spread these bacteria among cats, which subsequently inoculate the bacteria into humans through bites and scratches. The incidence of CSD in the United States is estimated to be 4.5 to 9.3 per 100,000 individuals in the outpatient setting and 0.19 to 0.86 per 100,000 individuals in the inpatient setting.¹ Geographic variance can occur based on flea populations, resulting in higher incidence in warm humid climates and lower incidence in mountainous arid climates. The incidence of CSD in the pediatric population is highest in children aged 5 to 9 years. A national representative survey (N=3011) from 2017 revealed that 37.2% of primary care providers had diagnosed CSD in the prior year.¹

Classic CSD presents as an erythematous papule at the inoculation site lasting days to weeks, with progression to tender lymphadenopathy lasting weeks to months. Fever, malaise, and chills also can be seen. Atypical CSD occurs in up to 24% of cases in immunocompetent patients.¹ Atypical and systemic presentations are varied and can include fever of unknown origin, neuroretinitis, uveitis, retinal vessel occlusion, encephalitis, hepatosplenic lesions, Parinaud oculoglandular syndrome, osteomyelitis, and endocarditis.^1,2 Atypical dermatologic presentations of CSD include maculopapular rash in 7% of cases and erythema nodosum in 2.5% of cases, as well as rare reports of cutaneous vasculitis, urticaria, immune thrombocytopenic purpura, and papuloedematous eruption.³ Treatment guidelines for CSD vary widely depending on the clinical presentation as well as the immunocompetence of the infected individual. Our patient had limited regional lymphadenopathy with no signs of dissemination or neurologic involvement and was successfully treated with a 5-day course of oral azithromycin (weight based, 10 mg/kg). More extensive disease such as hepatosplenic or neurologic CSD may require multiple antibiotics for up to 6 weeks. Alternative or additional antibiotics used for CSD include rifampin, trimethoprim-sulfamethoxazole, ciprofloxacin, doxycycline, gentamicin, and clarithromycin. Opinions vary as to whether all patients or just those with complicated infections warrant antibiotic therapy.^4-6

Pityriasis rosea is a self-limited acute exanthematous disease that is classically associated with a systemic reactivation of human herpesvirus (HHV) 6 and/or HHV-7. The incidence of PR is estimated to be 480 per 100,000 dermatologic patients. It is slightly more common in females and occurs most often in patients aged 10 to 35 years.⁷ Clinically, PR appears with the abrupt onset of a single erythematous scaly patch (termed the herald patch), followed by a secondary eruption of smaller erythematous scaly macules and patches along the trunk’s cleavage lines. The secondary eruption on the back is sometimes termed a Christmas or fir tree pattern.^7,8

In addition to the classic presentation of PR, there have been reports of numerous atypical clinical presentations. The herald patch, which classically presents on the trunk, also has been reported to present on the extremities; PR of the extremities is defined by lesions that appear as large scaly plaques on the extremities only. Inverse PR presents with lesions occurring in flexural areas and acral surfaces but not on the trunk. There also is an acral PR variant in which lesions appear only on the palms, wrists, and soles. Purpuric or hemorrhagic PR has been described and presents with purpura and petechiae with or without collarettes of scale in diffuse locations, including the palate. Oral PR presents more commonly in patients of color as erosions, ulcers, hemorrhagic lesions, bullae, or geographic tongue. Erythema multiforme–like PR appears with targetoid lesions on the trunk, face, neck, and arms without a history of herpes simplex virus infection. A large pear-shaped herald patch has been reported and characterizes the gigantea PR of Darier variant. Irritated PR occurs with typical PR findings, but afflicted patients report severe pain and burning with diaphoresis. Relapsing PR can occur within 1 year of a prior episode of PR and presents without a herald patch. Persistent PR is defined by PR lasting more than 3 months, and most reported cases have included oral lesions. Finally, other PR variants that have been described include urticarial, papular, follicular, vesicular, and hypopigmented types.^7-9

Furthermore, there have been reports of multiple atypical presentations occurring simultaneously in the same patient.¹⁰ Although PR classically has been associated with HHV-6 and/or HHV-7 reactivation, it has been reported with a few other clinical situations and conditions. Pityriasislike eruption specifically refers to an exanthem secondary to drugs or vaccination that resembles PR but shows clinical differences, including diffuse and confluent dusky-red macules and/or plaques with or without desquamation on the trunk, extremities, and face. Drugs that have been implicated as triggers include ACE inhibitors, gold, isotretinoin, nonsteroidal anti-inflammatory agents, omeprazole, terbinafine, and tyrosine kinase inhibitors. Smallpox, tuberculosis, poliomyelitis, influenza, diphtheria, tetanus, hepatitis B virus, pneumococcus, papillomavirus, yellow fever, and pertussis vaccinations also have been associated with PR.^7,11,12 Additionally, PR has been reported to occur with active systemic infections, specifically H1N1 influenza, though it is rare.¹³ Because of its self-limited course, treatment of PR most often involves only reassurance. Topical corticosteroids may be appropriate for pruritus.^7,8

Pediatric health care providers including dermatologists should be familiar with both CSD and PR because they are common diseases that more often are encountered in the pediatric population. We present a unique case of CSD presenting with concurrent PR, which highlights a potential new etiology for PR and a rare cutaneous manifestation of CSD. Further investigation into a possible relationship between CSD and PR may be warranted. Patients with any signs and symptoms of fever, tender lymphadenopathy, worsening rash, or exposure to cats warrant a thorough history and physical examination to ensure that neither entity is overlooked.

To the Editor:

Cat scratch disease (CSD) is caused by Bartonella henselae and Bartonella clarridgeiae bacteria transferred from cats to humans that results in an inflamed inoculation site and tender lymphadenopathy. Pityriasis rosea (PR) and PR-like eruptions are self-limited, acute exanthems that have been associated with infections, vaccinations, and medications. We report a case of PR occurring in a 10-year-old girl with CSD, which may suggest an association between the 2 diseases.

A 10-year-old girl who was otherwise healthy presented in the winter with a rash of 5 days’ duration. Fourteen days prior to the rash, the patient reported being scratched by a new kitten and noted a pinpoint “puncture” on the left forearm that developed into a red papule over the following week. Seven days after the cat scratch, the patient experienced pain and swelling in the left axilla. Approximately 1 week after the onset of lymphadenopathy, the patient developed an asymptomatic rash that started with a large spot on the left chest, followed by smaller spots appearing over the next 2 days and spreading to the rest of the trunk. Four days after the rash onset, the patient experienced a mild headache, low-grade subjective fever, and chills. She denied any recent travel, bug bites, sore throat, and diarrhea. She was up-to-date on all vaccinations and had not received any vaccines preceding the symptoms. Physical examination revealed a 2-cm pink, scaly, thin plaque with a collarette of scale on the left upper chest (herald patch), along with multiple thin pink papules and small plaques with central scale on the trunk (Figure 1). A pustule with adjacent linear erosion was present on the left ventral forearm (Figure 2). The patient had a tender subcutaneous nodule in the left axilla as well as bilateral anterior and posterior cervical-chain subcutaneous tender nodules. There was no involvement of the palms, soles, or mucosae.

The patient was empirically treated for CSD with azithromycin (200 mg/5 mL), 404 mg on day 1 followed by 202 mg daily for 4 days. The rash was treated with hydrocortisone cream 2.5% twice daily for 2 weeks. A wound culture of the pustule on the left forearm was negative for neutrophils and organisms. Antibody serologies obtained 4 weeks after presentation were notable for an elevated B henselae IgG titer of 1:640, confirming the diagnosis of CSD. Following treatment with azithromycin and hydrocortisone, all of the patient’s symptoms resolved after 1 to 2 weeks.

Cat scratch disease is a zoonotic infection caused by the bacteria B henselae and the more recently described pathogen B clarridgeiae. Cat fleas spread these bacteria among cats, which subsequently inoculate the bacteria into humans through bites and scratches. The incidence of CSD in the United States is estimated to be 4.5 to 9.3 per 100,000 individuals in the outpatient setting and 0.19 to 0.86 per 100,000 individuals in the inpatient setting.¹ Geographic variance can occur based on flea populations, resulting in higher incidence in warm humid climates and lower incidence in mountainous arid climates. The incidence of CSD in the pediatric population is highest in children aged 5 to 9 years. A national representative survey (N=3011) from 2017 revealed that 37.2% of primary care providers had diagnosed CSD in the prior year.¹

Classic CSD presents as an erythematous papule at the inoculation site lasting days to weeks, with progression to tender lymphadenopathy lasting weeks to months. Fever, malaise, and chills also can be seen. Atypical CSD occurs in up to 24% of cases in immunocompetent patients.¹ Atypical and systemic presentations are varied and can include fever of unknown origin, neuroretinitis, uveitis, retinal vessel occlusion, encephalitis, hepatosplenic lesions, Parinaud oculoglandular syndrome, osteomyelitis, and endocarditis.^1,2 Atypical dermatologic presentations of CSD include maculopapular rash in 7% of cases and erythema nodosum in 2.5% of cases, as well as rare reports of cutaneous vasculitis, urticaria, immune thrombocytopenic purpura, and papuloedematous eruption.³ Treatment guidelines for CSD vary widely depending on the clinical presentation as well as the immunocompetence of the infected individual. Our patient had limited regional lymphadenopathy with no signs of dissemination or neurologic involvement and was successfully treated with a 5-day course of oral azithromycin (weight based, 10 mg/kg). More extensive disease such as hepatosplenic or neurologic CSD may require multiple antibiotics for up to 6 weeks. Alternative or additional antibiotics used for CSD include rifampin, trimethoprim-sulfamethoxazole, ciprofloxacin, doxycycline, gentamicin, and clarithromycin. Opinions vary as to whether all patients or just those with complicated infections warrant antibiotic therapy.^4-6

Pityriasis rosea is a self-limited acute exanthematous disease that is classically associated with a systemic reactivation of human herpesvirus (HHV) 6 and/or HHV-7. The incidence of PR is estimated to be 480 per 100,000 dermatologic patients. It is slightly more common in females and occurs most often in patients aged 10 to 35 years.⁷ Clinically, PR appears with the abrupt onset of a single erythematous scaly patch (termed the herald patch), followed by a secondary eruption of smaller erythematous scaly macules and patches along the trunk’s cleavage lines. The secondary eruption on the back is sometimes termed a Christmas or fir tree pattern.^7,8

In addition to the classic presentation of PR, there have been reports of numerous atypical clinical presentations. The herald patch, which classically presents on the trunk, also has been reported to present on the extremities; PR of the extremities is defined by lesions that appear as large scaly plaques on the extremities only. Inverse PR presents with lesions occurring in flexural areas and acral surfaces but not on the trunk. There also is an acral PR variant in which lesions appear only on the palms, wrists, and soles. Purpuric or hemorrhagic PR has been described and presents with purpura and petechiae with or without collarettes of scale in diffuse locations, including the palate. Oral PR presents more commonly in patients of color as erosions, ulcers, hemorrhagic lesions, bullae, or geographic tongue. Erythema multiforme–like PR appears with targetoid lesions on the trunk, face, neck, and arms without a history of herpes simplex virus infection. A large pear-shaped herald patch has been reported and characterizes the gigantea PR of Darier variant. Irritated PR occurs with typical PR findings, but afflicted patients report severe pain and burning with diaphoresis. Relapsing PR can occur within 1 year of a prior episode of PR and presents without a herald patch. Persistent PR is defined by PR lasting more than 3 months, and most reported cases have included oral lesions. Finally, other PR variants that have been described include urticarial, papular, follicular, vesicular, and hypopigmented types.^7-9

Furthermore, there have been reports of multiple atypical presentations occurring simultaneously in the same patient.¹⁰ Although PR classically has been associated with HHV-6 and/or HHV-7 reactivation, it has been reported with a few other clinical situations and conditions. Pityriasislike eruption specifically refers to an exanthem secondary to drugs or vaccination that resembles PR but shows clinical differences, including diffuse and confluent dusky-red macules and/or plaques with or without desquamation on the trunk, extremities, and face. Drugs that have been implicated as triggers include ACE inhibitors, gold, isotretinoin, nonsteroidal anti-inflammatory agents, omeprazole, terbinafine, and tyrosine kinase inhibitors. Smallpox, tuberculosis, poliomyelitis, influenza, diphtheria, tetanus, hepatitis B virus, pneumococcus, papillomavirus, yellow fever, and pertussis vaccinations also have been associated with PR.^7,11,12 Additionally, PR has been reported to occur with active systemic infections, specifically H1N1 influenza, though it is rare.¹³ Because of its self-limited course, treatment of PR most often involves only reassurance. Topical corticosteroids may be appropriate for pruritus.^7,8

Pediatric health care providers including dermatologists should be familiar with both CSD and PR because they are common diseases that more often are encountered in the pediatric population. We present a unique case of CSD presenting with concurrent PR, which highlights a potential new etiology for PR and a rare cutaneous manifestation of CSD. Further investigation into a possible relationship between CSD and PR may be warranted. Patients with any signs and symptoms of fever, tender lymphadenopathy, worsening rash, or exposure to cats warrant a thorough history and physical examination to ensure that neither entity is overlooked.

To the Editor:

Cat scratch disease (CSD) is caused by Bartonella henselae and Bartonella clarridgeiae bacteria transferred from cats to humans that results in an inflamed inoculation site and tender lymphadenopathy. Pityriasis rosea (PR) and PR-like eruptions are self-limited, acute exanthems that have been associated with infections, vaccinations, and medications. We report a case of PR occurring in a 10-year-old girl with CSD, which may suggest an association between the 2 diseases.

A 10-year-old girl who was otherwise healthy presented in the winter with a rash of 5 days’ duration. Fourteen days prior to the rash, the patient reported being scratched by a new kitten and noted a pinpoint “puncture” on the left forearm that developed into a red papule over the following week. Seven days after the cat scratch, the patient experienced pain and swelling in the left axilla. Approximately 1 week after the onset of lymphadenopathy, the patient developed an asymptomatic rash that started with a large spot on the left chest, followed by smaller spots appearing over the next 2 days and spreading to the rest of the trunk. Four days after the rash onset, the patient experienced a mild headache, low-grade subjective fever, and chills. She denied any recent travel, bug bites, sore throat, and diarrhea. She was up-to-date on all vaccinations and had not received any vaccines preceding the symptoms. Physical examination revealed a 2-cm pink, scaly, thin plaque with a collarette of scale on the left upper chest (herald patch), along with multiple thin pink papules and small plaques with central scale on the trunk (Figure 1). A pustule with adjacent linear erosion was present on the left ventral forearm (Figure 2). The patient had a tender subcutaneous nodule in the left axilla as well as bilateral anterior and posterior cervical-chain subcutaneous tender nodules. There was no involvement of the palms, soles, or mucosae.

The patient was empirically treated for CSD with azithromycin (200 mg/5 mL), 404 mg on day 1 followed by 202 mg daily for 4 days. The rash was treated with hydrocortisone cream 2.5% twice daily for 2 weeks. A wound culture of the pustule on the left forearm was negative for neutrophils and organisms. Antibody serologies obtained 4 weeks after presentation were notable for an elevated B henselae IgG titer of 1:640, confirming the diagnosis of CSD. Following treatment with azithromycin and hydrocortisone, all of the patient’s symptoms resolved after 1 to 2 weeks.

Cat scratch disease is a zoonotic infection caused by the bacteria B henselae and the more recently described pathogen B clarridgeiae. Cat fleas spread these bacteria among cats, which subsequently inoculate the bacteria into humans through bites and scratches. The incidence of CSD in the United States is estimated to be 4.5 to 9.3 per 100,000 individuals in the outpatient setting and 0.19 to 0.86 per 100,000 individuals in the inpatient setting.¹ Geographic variance can occur based on flea populations, resulting in higher incidence in warm humid climates and lower incidence in mountainous arid climates. The incidence of CSD in the pediatric population is highest in children aged 5 to 9 years. A national representative survey (N=3011) from 2017 revealed that 37.2% of primary care providers had diagnosed CSD in the prior year.¹

Classic CSD presents as an erythematous papule at the inoculation site lasting days to weeks, with progression to tender lymphadenopathy lasting weeks to months. Fever, malaise, and chills also can be seen. Atypical CSD occurs in up to 24% of cases in immunocompetent patients.¹ Atypical and systemic presentations are varied and can include fever of unknown origin, neuroretinitis, uveitis, retinal vessel occlusion, encephalitis, hepatosplenic lesions, Parinaud oculoglandular syndrome, osteomyelitis, and endocarditis.^1,2 Atypical dermatologic presentations of CSD include maculopapular rash in 7% of cases and erythema nodosum in 2.5% of cases, as well as rare reports of cutaneous vasculitis, urticaria, immune thrombocytopenic purpura, and papuloedematous eruption.³ Treatment guidelines for CSD vary widely depending on the clinical presentation as well as the immunocompetence of the infected individual. Our patient had limited regional lymphadenopathy with no signs of dissemination or neurologic involvement and was successfully treated with a 5-day course of oral azithromycin (weight based, 10 mg/kg). More extensive disease such as hepatosplenic or neurologic CSD may require multiple antibiotics for up to 6 weeks. Alternative or additional antibiotics used for CSD include rifampin, trimethoprim-sulfamethoxazole, ciprofloxacin, doxycycline, gentamicin, and clarithromycin. Opinions vary as to whether all patients or just those with complicated infections warrant antibiotic therapy.^4-6

Pityriasis rosea is a self-limited acute exanthematous disease that is classically associated with a systemic reactivation of human herpesvirus (HHV) 6 and/or HHV-7. The incidence of PR is estimated to be 480 per 100,000 dermatologic patients. It is slightly more common in females and occurs most often in patients aged 10 to 35 years.⁷ Clinically, PR appears with the abrupt onset of a single erythematous scaly patch (termed the herald patch), followed by a secondary eruption of smaller erythematous scaly macules and patches along the trunk’s cleavage lines. The secondary eruption on the back is sometimes termed a Christmas or fir tree pattern.^7,8

In addition to the classic presentation of PR, there have been reports of numerous atypical clinical presentations. The herald patch, which classically presents on the trunk, also has been reported to present on the extremities; PR of the extremities is defined by lesions that appear as large scaly plaques on the extremities only. Inverse PR presents with lesions occurring in flexural areas and acral surfaces but not on the trunk. There also is an acral PR variant in which lesions appear only on the palms, wrists, and soles. Purpuric or hemorrhagic PR has been described and presents with purpura and petechiae with or without collarettes of scale in diffuse locations, including the palate. Oral PR presents more commonly in patients of color as erosions, ulcers, hemorrhagic lesions, bullae, or geographic tongue. Erythema multiforme–like PR appears with targetoid lesions on the trunk, face, neck, and arms without a history of herpes simplex virus infection. A large pear-shaped herald patch has been reported and characterizes the gigantea PR of Darier variant. Irritated PR occurs with typical PR findings, but afflicted patients report severe pain and burning with diaphoresis. Relapsing PR can occur within 1 year of a prior episode of PR and presents without a herald patch. Persistent PR is defined by PR lasting more than 3 months, and most reported cases have included oral lesions. Finally, other PR variants that have been described include urticarial, papular, follicular, vesicular, and hypopigmented types.^7-9

Furthermore, there have been reports of multiple atypical presentations occurring simultaneously in the same patient.¹⁰ Although PR classically has been associated with HHV-6 and/or HHV-7 reactivation, it has been reported with a few other clinical situations and conditions. Pityriasislike eruption specifically refers to an exanthem secondary to drugs or vaccination that resembles PR but shows clinical differences, including diffuse and confluent dusky-red macules and/or plaques with or without desquamation on the trunk, extremities, and face. Drugs that have been implicated as triggers include ACE inhibitors, gold, isotretinoin, nonsteroidal anti-inflammatory agents, omeprazole, terbinafine, and tyrosine kinase inhibitors. Smallpox, tuberculosis, poliomyelitis, influenza, diphtheria, tetanus, hepatitis B virus, pneumococcus, papillomavirus, yellow fever, and pertussis vaccinations also have been associated with PR.^7,11,12 Additionally, PR has been reported to occur with active systemic infections, specifically H1N1 influenza, though it is rare.¹³ Because of its self-limited course, treatment of PR most often involves only reassurance. Topical corticosteroids may be appropriate for pruritus.^7,8

Pediatric health care providers including dermatologists should be familiar with both CSD and PR because they are common diseases that more often are encountered in the pediatric population. We present a unique case of CSD presenting with concurrent PR, which highlights a potential new etiology for PR and a rare cutaneous manifestation of CSD. Further investigation into a possible relationship between CSD and PR may be warranted. Patients with any signs and symptoms of fever, tender lymphadenopathy, worsening rash, or exposure to cats warrant a thorough history and physical examination to ensure that neither entity is overlooked.

The Diagnosis: Scabies Infestation

Direct microscopy revealed the presence of a live scabies mite and numerous eggs (Figure), confirming the diagnosis of a scabies infestation. Scabies, caused by the Sarcoptes scabiei var hominis mite, characteristically presents in adults as pruritic hyperkeratotic plaques of the interdigital web spaces of the hands, flexor surfaces of the wrists and elbows, axillae, male genitalia, and breasts; however, an atypical presentation is common in immunocompromised or immunosuppressed individuals, such as our patient. In children, the palms, soles, and head (ie, face, scalp, neck) are common sites of involvement. Although dermatologists generally are familiar with severe atypical presentations such as Norwegian crusted scabies or bullous scabies, it is important that they are aware of other atypical presentations, such as the diffuse papulonodular variant observed in our patient.¹ As such, a low threshold of suspicion for scabies infestations should be employed in immunocompromised patients with new-onset pruritic eruptions.

Direct microscopy is widely accepted as the gold standard for the diagnosis of scabies infestations; it is a fast and low-cost diagnostic tool. However, this technique displays variable sensitivity in clinical practice, requiring experience and a skilled hand.^1,2 Other more sensitive diagnostic options for suspected scabies infestations include histopathology, serology, and molecular-based techniques such as DNA isolation and polymerase chain reaction. Although these tests do demonstrate greater sensitivity, they also are more invasive, time intensive, and costly.² Therefore, they typically are not the first choice for a suspected scabies infestation. Dermoscopy has emerged as another tool to aid in the diagnosis of a suspected scabies infestation, enabling visualization of scaly burrows, eggs, and live mites. Classically, findings resembling a delta wing with contrail are seen on dermoscopic examination. The delta wing represents the brown triangular structure of the pigmented scabies mite head and anterior legs; the contrail is the lighter linear structures streaming behind the scabies mite (similar to visible vapor streams occurring behind flying jets), representing the burrow of the mite.

Although treatment of scabies infestations typically can be accomplished with permethrin cream 5%, the diffuse nature of our patient’s lesions in combination with his immunocompromised state made oral therapy a more appropriate choice. Based on Centers for Disease Control and Prevention recommendations, the patient received 2 doses of oral weight-based ivermectin (200 μg/kg per dose) administered 1 week apart.^1,3 The initial dose at day 1 serves to eliminate any scabies mites that are present, while the second dose 1 week later eliminates any residual eggs. Our patient experienced complete resolution of the symptoms following this treatment regimen.

It was important to differentiate our patient’s scabies infestation from other intensely pruritic conditions and morphologic mimics including papular urticaria, lichenoid drug eruptions, tinea corporis, and prurigo nodularis. Papular urticaria is an intensely pruritic hypersensitivity reaction to insect bites that commonly affects the extremities or other exposed areas. Visible puncta may be present.⁴ Our patient’s lesion distribution involved areas covered by clothing, no puncta were present, and he had no history of a recent arthropod assault, making the diagnosis of papular urticaria less likely.

Lichenoid drug eruptions classically present with symmetric, diffuse, pruritic, violaceous, scaling papules and plaques that present 2 to 3 months after exposure to an offending agent.⁵ Our patient’s eruption was papulonodular with no violaceous plaques, and he did not report changes to his medications, making a lichenoid drug eruption less likely.

Tinea corporis is another intensely pruritic condition that should be considered, especially in immunocompromised patients. It is caused by dermatophytes and classically presents as erythematous pruritic plaques with an annular, advancing, scaling border.⁶ Although immunocompromised patients may display extensive involvement, our patient’s lesions were papulonodular with no annular morphology or scale, rendering tinea corporis less likely.

Prurigo nodularis is a chronic condition characterized by pruritic, violaceous, dome-shaped, smooth or crusted nodules secondary to repeated scratching or pressure. Although prurigo nodules can develop as a secondary change due to chronic excoriations in scabies infestations, prurigo nodules usually do not develop in areas such as the midline of the back that are not easily reached by the fingernails,⁷ which made prurigo nodularis less likely in our patient.

This case describes a unique papulonodular variant of scabies presenting in an immunocompromised cancer patient. Timely recognition and diagnosis of atypical scabies infestations can decrease morbidity and improve the quality of life of these patients.

The Diagnosis: Scabies Infestation

Direct microscopy revealed the presence of a live scabies mite and numerous eggs (Figure), confirming the diagnosis of a scabies infestation. Scabies, caused by the Sarcoptes scabiei var hominis mite, characteristically presents in adults as pruritic hyperkeratotic plaques of the interdigital web spaces of the hands, flexor surfaces of the wrists and elbows, axillae, male genitalia, and breasts; however, an atypical presentation is common in immunocompromised or immunosuppressed individuals, such as our patient. In children, the palms, soles, and head (ie, face, scalp, neck) are common sites of involvement. Although dermatologists generally are familiar with severe atypical presentations such as Norwegian crusted scabies or bullous scabies, it is important that they are aware of other atypical presentations, such as the diffuse papulonodular variant observed in our patient.¹ As such, a low threshold of suspicion for scabies infestations should be employed in immunocompromised patients with new-onset pruritic eruptions.

Direct microscopy is widely accepted as the gold standard for the diagnosis of scabies infestations; it is a fast and low-cost diagnostic tool. However, this technique displays variable sensitivity in clinical practice, requiring experience and a skilled hand.^1,2 Other more sensitive diagnostic options for suspected scabies infestations include histopathology, serology, and molecular-based techniques such as DNA isolation and polymerase chain reaction. Although these tests do demonstrate greater sensitivity, they also are more invasive, time intensive, and costly.² Therefore, they typically are not the first choice for a suspected scabies infestation. Dermoscopy has emerged as another tool to aid in the diagnosis of a suspected scabies infestation, enabling visualization of scaly burrows, eggs, and live mites. Classically, findings resembling a delta wing with contrail are seen on dermoscopic examination. The delta wing represents the brown triangular structure of the pigmented scabies mite head and anterior legs; the contrail is the lighter linear structures streaming behind the scabies mite (similar to visible vapor streams occurring behind flying jets), representing the burrow of the mite.

Although treatment of scabies infestations typically can be accomplished with permethrin cream 5%, the diffuse nature of our patient’s lesions in combination with his immunocompromised state made oral therapy a more appropriate choice. Based on Centers for Disease Control and Prevention recommendations, the patient received 2 doses of oral weight-based ivermectin (200 μg/kg per dose) administered 1 week apart.^1,3 The initial dose at day 1 serves to eliminate any scabies mites that are present, while the second dose 1 week later eliminates any residual eggs. Our patient experienced complete resolution of the symptoms following this treatment regimen.

It was important to differentiate our patient’s scabies infestation from other intensely pruritic conditions and morphologic mimics including papular urticaria, lichenoid drug eruptions, tinea corporis, and prurigo nodularis. Papular urticaria is an intensely pruritic hypersensitivity reaction to insect bites that commonly affects the extremities or other exposed areas. Visible puncta may be present.⁴ Our patient’s lesion distribution involved areas covered by clothing, no puncta were present, and he had no history of a recent arthropod assault, making the diagnosis of papular urticaria less likely.

Lichenoid drug eruptions classically present with symmetric, diffuse, pruritic, violaceous, scaling papules and plaques that present 2 to 3 months after exposure to an offending agent.⁵ Our patient’s eruption was papulonodular with no violaceous plaques, and he did not report changes to his medications, making a lichenoid drug eruption less likely.

Tinea corporis is another intensely pruritic condition that should be considered, especially in immunocompromised patients. It is caused by dermatophytes and classically presents as erythematous pruritic plaques with an annular, advancing, scaling border.⁶ Although immunocompromised patients may display extensive involvement, our patient’s lesions were papulonodular with no annular morphology or scale, rendering tinea corporis less likely.

Prurigo nodularis is a chronic condition characterized by pruritic, violaceous, dome-shaped, smooth or crusted nodules secondary to repeated scratching or pressure. Although prurigo nodules can develop as a secondary change due to chronic excoriations in scabies infestations, prurigo nodules usually do not develop in areas such as the midline of the back that are not easily reached by the fingernails,⁷ which made prurigo nodularis less likely in our patient.

This case describes a unique papulonodular variant of scabies presenting in an immunocompromised cancer patient. Timely recognition and diagnosis of atypical scabies infestations can decrease morbidity and improve the quality of life of these patients.

The Diagnosis: Scabies Infestation

Direct microscopy revealed the presence of a live scabies mite and numerous eggs (Figure), confirming the diagnosis of a scabies infestation. Scabies, caused by the Sarcoptes scabiei var hominis mite, characteristically presents in adults as pruritic hyperkeratotic plaques of the interdigital web spaces of the hands, flexor surfaces of the wrists and elbows, axillae, male genitalia, and breasts; however, an atypical presentation is common in immunocompromised or immunosuppressed individuals, such as our patient. In children, the palms, soles, and head (ie, face, scalp, neck) are common sites of involvement. Although dermatologists generally are familiar with severe atypical presentations such as Norwegian crusted scabies or bullous scabies, it is important that they are aware of other atypical presentations, such as the diffuse papulonodular variant observed in our patient.¹ As such, a low threshold of suspicion for scabies infestations should be employed in immunocompromised patients with new-onset pruritic eruptions.

Direct microscopy is widely accepted as the gold standard for the diagnosis of scabies infestations; it is a fast and low-cost diagnostic tool. However, this technique displays variable sensitivity in clinical practice, requiring experience and a skilled hand.^1,2 Other more sensitive diagnostic options for suspected scabies infestations include histopathology, serology, and molecular-based techniques such as DNA isolation and polymerase chain reaction. Although these tests do demonstrate greater sensitivity, they also are more invasive, time intensive, and costly.² Therefore, they typically are not the first choice for a suspected scabies infestation. Dermoscopy has emerged as another tool to aid in the diagnosis of a suspected scabies infestation, enabling visualization of scaly burrows, eggs, and live mites. Classically, findings resembling a delta wing with contrail are seen on dermoscopic examination. The delta wing represents the brown triangular structure of the pigmented scabies mite head and anterior legs; the contrail is the lighter linear structures streaming behind the scabies mite (similar to visible vapor streams occurring behind flying jets), representing the burrow of the mite.

Although treatment of scabies infestations typically can be accomplished with permethrin cream 5%, the diffuse nature of our patient’s lesions in combination with his immunocompromised state made oral therapy a more appropriate choice. Based on Centers for Disease Control and Prevention recommendations, the patient received 2 doses of oral weight-based ivermectin (200 μg/kg per dose) administered 1 week apart.^1,3 The initial dose at day 1 serves to eliminate any scabies mites that are present, while the second dose 1 week later eliminates any residual eggs. Our patient experienced complete resolution of the symptoms following this treatment regimen.

It was important to differentiate our patient’s scabies infestation from other intensely pruritic conditions and morphologic mimics including papular urticaria, lichenoid drug eruptions, tinea corporis, and prurigo nodularis. Papular urticaria is an intensely pruritic hypersensitivity reaction to insect bites that commonly affects the extremities or other exposed areas. Visible puncta may be present.⁴ Our patient’s lesion distribution involved areas covered by clothing, no puncta were present, and he had no history of a recent arthropod assault, making the diagnosis of papular urticaria less likely.

Lichenoid drug eruptions classically present with symmetric, diffuse, pruritic, violaceous, scaling papules and plaques that present 2 to 3 months after exposure to an offending agent.⁵ Our patient’s eruption was papulonodular with no violaceous plaques, and he did not report changes to his medications, making a lichenoid drug eruption less likely.

Tinea corporis is another intensely pruritic condition that should be considered, especially in immunocompromised patients. It is caused by dermatophytes and classically presents as erythematous pruritic plaques with an annular, advancing, scaling border.⁶ Although immunocompromised patients may display extensive involvement, our patient’s lesions were papulonodular with no annular morphology or scale, rendering tinea corporis less likely.

Prurigo nodularis is a chronic condition characterized by pruritic, violaceous, dome-shaped, smooth or crusted nodules secondary to repeated scratching or pressure. Although prurigo nodules can develop as a secondary change due to chronic excoriations in scabies infestations, prurigo nodules usually do not develop in areas such as the midline of the back that are not easily reached by the fingernails,⁷ which made prurigo nodularis less likely in our patient.

This case describes a unique papulonodular variant of scabies presenting in an immunocompromised cancer patient. Timely recognition and diagnosis of atypical scabies infestations can decrease morbidity and improve the quality of life of these patients.

The Diagnosis: Infantile Transient Smooth Muscle Contraction of the Skin

A diagnosis of infantile transient smooth muscle contraction of the skin (ITSMC) was made based on our patient’s clinical presentation and eliminating the diagnoses in the differential. No treatment ultimately was indicated, as episodes became less frequent over time.

The term infantile transient smooth muscle contraction of the skin was first proposed in 2013 by Torrelo et al,¹ who described 9 newborns with episodic skin rippling occasionally associated with exposure to cold or friction. The authors postulated that ITSMC was the result of a transient contraction of the arrector pili smooth muscle fibers of the skin, secondary to autonomic immaturity, primitive reflexes, or smooth muscle hypersensitivity.¹ Since this first description, ITSMC has remained a rarely reported and poorly understood phenomenon with rare identified cases in the literature.^2,3 Clinical history and examination of infants with intermittent transient skin rippling help to distinguish ITSMC from other diagnoses without the need for biopsy, which is particularly undesirable in the pediatric population.

Congenital smooth muscle hamartoma is a benign proliferation of mature smooth muscle that also can arise from the arrector pili muscles.⁴ In contrast to ITSMC, a hamartoma does not clear; rather, it persists and grows proportionally with the child and is associated with overlying hyperpigmentation and hypertrichosis. The transient nature of ITSMC may be worrisome for mastocytoma; however, this condition presents as erythematous, yellow, red, or brown macules, papules, plaques, or nodules with a positive Darier sign.⁵ Although the differential diagnosis includes the shagreen patch characteristic of tuberous sclerosis, this irregular plaque typically is located on the lower back with overlying peau d’orange skin changes, and our patient lacked other features indicative of this condition.⁶ Becker nevus also remains a consideration in patients with rippled skin, but this entity typically becomes more notable at puberty and is associated with hyperpigmentation and hypertrichosis and is a type of smooth muscle hamartoma.⁴

Our case highlighted the unusual presentation of ITSMC, a condition that can easily go unrecognized, leading to unnecessary referrals and concern. Familiarity with this benign diagnosis is essential to inform prognosis and guide management.

The Diagnosis: Infantile Transient Smooth Muscle Contraction of the Skin

A diagnosis of infantile transient smooth muscle contraction of the skin (ITSMC) was made based on our patient’s clinical presentation and eliminating the diagnoses in the differential. No treatment ultimately was indicated, as episodes became less frequent over time.

The term infantile transient smooth muscle contraction of the skin was first proposed in 2013 by Torrelo et al,¹ who described 9 newborns with episodic skin rippling occasionally associated with exposure to cold or friction. The authors postulated that ITSMC was the result of a transient contraction of the arrector pili smooth muscle fibers of the skin, secondary to autonomic immaturity, primitive reflexes, or smooth muscle hypersensitivity.¹ Since this first description, ITSMC has remained a rarely reported and poorly understood phenomenon with rare identified cases in the literature.^2,3 Clinical history and examination of infants with intermittent transient skin rippling help to distinguish ITSMC from other diagnoses without the need for biopsy, which is particularly undesirable in the pediatric population.

Congenital smooth muscle hamartoma is a benign proliferation of mature smooth muscle that also can arise from the arrector pili muscles.⁴ In contrast to ITSMC, a hamartoma does not clear; rather, it persists and grows proportionally with the child and is associated with overlying hyperpigmentation and hypertrichosis. The transient nature of ITSMC may be worrisome for mastocytoma; however, this condition presents as erythematous, yellow, red, or brown macules, papules, plaques, or nodules with a positive Darier sign.⁵ Although the differential diagnosis includes the shagreen patch characteristic of tuberous sclerosis, this irregular plaque typically is located on the lower back with overlying peau d’orange skin changes, and our patient lacked other features indicative of this condition.⁶ Becker nevus also remains a consideration in patients with rippled skin, but this entity typically becomes more notable at puberty and is associated with hyperpigmentation and hypertrichosis and is a type of smooth muscle hamartoma.⁴

Our case highlighted the unusual presentation of ITSMC, a condition that can easily go unrecognized, leading to unnecessary referrals and concern. Familiarity with this benign diagnosis is essential to inform prognosis and guide management.

The Diagnosis: Infantile Transient Smooth Muscle Contraction of the Skin

A diagnosis of infantile transient smooth muscle contraction of the skin (ITSMC) was made based on our patient’s clinical presentation and eliminating the diagnoses in the differential. No treatment ultimately was indicated, as episodes became less frequent over time.

The term infantile transient smooth muscle contraction of the skin was first proposed in 2013 by Torrelo et al,¹ who described 9 newborns with episodic skin rippling occasionally associated with exposure to cold or friction. The authors postulated that ITSMC was the result of a transient contraction of the arrector pili smooth muscle fibers of the skin, secondary to autonomic immaturity, primitive reflexes, or smooth muscle hypersensitivity.¹ Since this first description, ITSMC has remained a rarely reported and poorly understood phenomenon with rare identified cases in the literature.^2,3 Clinical history and examination of infants with intermittent transient skin rippling help to distinguish ITSMC from other diagnoses without the need for biopsy, which is particularly undesirable in the pediatric population.

Congenital smooth muscle hamartoma is a benign proliferation of mature smooth muscle that also can arise from the arrector pili muscles.⁴ In contrast to ITSMC, a hamartoma does not clear; rather, it persists and grows proportionally with the child and is associated with overlying hyperpigmentation and hypertrichosis. The transient nature of ITSMC may be worrisome for mastocytoma; however, this condition presents as erythematous, yellow, red, or brown macules, papules, plaques, or nodules with a positive Darier sign.⁵ Although the differential diagnosis includes the shagreen patch characteristic of tuberous sclerosis, this irregular plaque typically is located on the lower back with overlying peau d’orange skin changes, and our patient lacked other features indicative of this condition.⁶ Becker nevus also remains a consideration in patients with rippled skin, but this entity typically becomes more notable at puberty and is associated with hyperpigmentation and hypertrichosis and is a type of smooth muscle hamartoma.⁴

Our case highlighted the unusual presentation of ITSMC, a condition that can easily go unrecognized, leading to unnecessary referrals and concern. Familiarity with this benign diagnosis is essential to inform prognosis and guide management.