Olayemi Sokumbi, MD

To the Editor:

Micrographic surgery and dermatologic oncology (MSDO) is a highly competitive subspecialty fellowship in dermatology. Prospective applicants often depend on the Internet to obtain pertinent information about fellowship programs to navigate the application process. An up-to-date and comprehensive fellowship website has the potential to be advantageous for both applicants and programs—applicants can more readily identify programs that align with their goals and values, and programs can effectively attract compatible applicants. These advantages are increasingly relevant with the virtual application process that has become essential considering the COVID-19 pandemic. At the height of the COVID-19 pandemic in 2020, we sought to evaluate the comprehensiveness of the content of Accreditation Council for Graduate Medical Education (ACGME) MSDO fellowship program websites to identify possible areas for improvement.

We obtained a list of all ACGME MSDO fellowships from the ACGME website (https://www.acgme.org/) and verified it against the list of MSDO programs in FREIDA, the American Medical Association residency and fellowship database (https://freida.ama-assn.org/). All programs without a website were excluded from further analysis. All data collection from currently accessible fellowship websites and evaluation occurred in April 2020.

The remaining MSDO fellowship program websites were evaluated using 25 criteria distributed among 5 domains: education/research, clinical training, program information, application process, and incentives. These criteria were determined based on earlier studies that similarly evaluated the website content of fellowship programs with inclusion of information that was considered valuable in the appraisal of fellowship programs.^1,2 Criteria were further refined by direct consideration of relevance and importance to MSDO fellowship applicants (eg, inclusion of case volume, exclusion of call schedule).

Each criterion was independently assessed by 2 investigators (J.Y.C. and S.J.E.S.). A third investigator (J.R.P.) then independently evaluated those 2 assessments for agreement. Where disagreement was discovered, the third evaluator (J.R.P.) provided a final appraisal. Cohen’s kappa (κ) was conducted to evaluate for concordance between the 2 primary website evaluators. We found there to be substantial agreement between the reviewers within the education/research (κ [SD]=0.772 [0.077]), clinical training (κ [SD]=0.740 [0.051]), application process (κ [SD]=0.726 [0.103]), and incentives domains (κ [SD]=0.730 [0.110]). There was moderate agreement (κ [SD]=0.603 [0.128]) between the reviewers within the program information domain.

We identified 77 active MSDO fellowship programs. Sixty of those 77 programs (77.9%) had a dedicated fellowship website that was readily accessible. Most programs that had a dedicated fellowship website had a core or affiliated residency program (49/60 [81.7%]).

Websites that we evaluated fulfilled a mean (SD) of 9.37 (4.17) of the 25 identified criteria. Only 13 of 60 (21.7%) websites fulfilled more than 50% of evaluated criteria.

There was no statistical difference in the number of criteria fulfilled based on whether the fellowship program had a core or affiliated residency program.

Upon reviewing website accessibility directly from FREIDA, only 5 of 60 programs (8.3%) provided applicants with a link directly to their fellowship page (Table). Most programs (41 [68.3%]) provided a link to the dermatology department website, not to the specific fellowship program page, thus requiring a multistep process to find the fellowship-specific page. The remaining programs had an inaccessible (4 [6.7%]) or absent (10 [16.7%]) link on FREIDA, though a fellowship website could be identified by an Internet search of the program name.

The domain most fulfilled was program information with an average of 51.1% of programs satisfying the criteria, whereas the incentives domain was least fulfilled with an average of only 20.8% of programs satisfying the criteria. Across the various criteria, websites more often included a description of the program (58 [96.6%]), mentioned accreditation (53 [88.3%]), and provided case descriptions (48 [80.0%]). They less often reported information regarding a fellow’s call responsibility (3 [5%]); evaluation criteria (5 [8.3%]); and rotation schedule or options (6 [10.0%]).

The highest number of criteria fulfilled by a single program was 19 (76%). The lowest number of criteria met was 2 (8%). These findings suggest a large variation in comprehensiveness across fellowship websites.

Our research suggests that many current MSDO fellowship programs have room to maximize the information provided to applicants through their websites, which is particularly relevant following the COVID-19 pandemic, as the value of providing comprehensive and transparent information through an online platform is greater than ever. Given the ongoing desire to limit travel, virtual methods for navigating the application process have been readily used, including online videoconferencing for interviews and virtual program visits. This scenario has placed applicants in a challenging situation—their ability to directly evaluate their compatibility with a given program has been limited.³

Earlier studies that analyzed rheumatology fellowship recruitment during the COVID-19 pandemic found that programs may have more difficulty highlighting the strengths of their institution (eg, clinical facilities, professional opportunities, educational environment).⁴ An updated and comprehensive fellowship website was recommended⁴ as a key part in facing these new challenges. On the other hand, given the large number of applicants each year for fellowship positions in any given program, we acknowledge the potential benefit programs may obtain from limiting electronic information that is readily accessible to all applicants, as doing so may encourage applicants to communicate directly with a program and allow programs to identify candidates who are more interested.

In light of the movement to a more virtual-friendly and technology-driven fellowship application process, we identified 25 content areas that fellowships may want to include on their websites so that potential applicants can be well informed about the program before submitting an application and scheduling an interview. Efforts to improve accessibility and maximize the content of these websites may help programs attract compatible candidates, improve transparency, and guide applicants throughout the application process.

To the Editor:

Micrographic surgery and dermatologic oncology (MSDO) is a highly competitive subspecialty fellowship in dermatology. Prospective applicants often depend on the Internet to obtain pertinent information about fellowship programs to navigate the application process. An up-to-date and comprehensive fellowship website has the potential to be advantageous for both applicants and programs—applicants can more readily identify programs that align with their goals and values, and programs can effectively attract compatible applicants. These advantages are increasingly relevant with the virtual application process that has become essential considering the COVID-19 pandemic. At the height of the COVID-19 pandemic in 2020, we sought to evaluate the comprehensiveness of the content of Accreditation Council for Graduate Medical Education (ACGME) MSDO fellowship program websites to identify possible areas for improvement.

We obtained a list of all ACGME MSDO fellowships from the ACGME website (https://www.acgme.org/) and verified it against the list of MSDO programs in FREIDA, the American Medical Association residency and fellowship database (https://freida.ama-assn.org/). All programs without a website were excluded from further analysis. All data collection from currently accessible fellowship websites and evaluation occurred in April 2020.

The remaining MSDO fellowship program websites were evaluated using 25 criteria distributed among 5 domains: education/research, clinical training, program information, application process, and incentives. These criteria were determined based on earlier studies that similarly evaluated the website content of fellowship programs with inclusion of information that was considered valuable in the appraisal of fellowship programs.^1,2 Criteria were further refined by direct consideration of relevance and importance to MSDO fellowship applicants (eg, inclusion of case volume, exclusion of call schedule).

Each criterion was independently assessed by 2 investigators (J.Y.C. and S.J.E.S.). A third investigator (J.R.P.) then independently evaluated those 2 assessments for agreement. Where disagreement was discovered, the third evaluator (J.R.P.) provided a final appraisal. Cohen’s kappa (κ) was conducted to evaluate for concordance between the 2 primary website evaluators. We found there to be substantial agreement between the reviewers within the education/research (κ [SD]=0.772 [0.077]), clinical training (κ [SD]=0.740 [0.051]), application process (κ [SD]=0.726 [0.103]), and incentives domains (κ [SD]=0.730 [0.110]). There was moderate agreement (κ [SD]=0.603 [0.128]) between the reviewers within the program information domain.

We identified 77 active MSDO fellowship programs. Sixty of those 77 programs (77.9%) had a dedicated fellowship website that was readily accessible. Most programs that had a dedicated fellowship website had a core or affiliated residency program (49/60 [81.7%]).

Websites that we evaluated fulfilled a mean (SD) of 9.37 (4.17) of the 25 identified criteria. Only 13 of 60 (21.7%) websites fulfilled more than 50% of evaluated criteria.

There was no statistical difference in the number of criteria fulfilled based on whether the fellowship program had a core or affiliated residency program.

Upon reviewing website accessibility directly from FREIDA, only 5 of 60 programs (8.3%) provided applicants with a link directly to their fellowship page (Table). Most programs (41 [68.3%]) provided a link to the dermatology department website, not to the specific fellowship program page, thus requiring a multistep process to find the fellowship-specific page. The remaining programs had an inaccessible (4 [6.7%]) or absent (10 [16.7%]) link on FREIDA, though a fellowship website could be identified by an Internet search of the program name.

The domain most fulfilled was program information with an average of 51.1% of programs satisfying the criteria, whereas the incentives domain was least fulfilled with an average of only 20.8% of programs satisfying the criteria. Across the various criteria, websites more often included a description of the program (58 [96.6%]), mentioned accreditation (53 [88.3%]), and provided case descriptions (48 [80.0%]). They less often reported information regarding a fellow’s call responsibility (3 [5%]); evaluation criteria (5 [8.3%]); and rotation schedule or options (6 [10.0%]).

The highest number of criteria fulfilled by a single program was 19 (76%). The lowest number of criteria met was 2 (8%). These findings suggest a large variation in comprehensiveness across fellowship websites.

Our research suggests that many current MSDO fellowship programs have room to maximize the information provided to applicants through their websites, which is particularly relevant following the COVID-19 pandemic, as the value of providing comprehensive and transparent information through an online platform is greater than ever. Given the ongoing desire to limit travel, virtual methods for navigating the application process have been readily used, including online videoconferencing for interviews and virtual program visits. This scenario has placed applicants in a challenging situation—their ability to directly evaluate their compatibility with a given program has been limited.³

Earlier studies that analyzed rheumatology fellowship recruitment during the COVID-19 pandemic found that programs may have more difficulty highlighting the strengths of their institution (eg, clinical facilities, professional opportunities, educational environment).⁴ An updated and comprehensive fellowship website was recommended⁴ as a key part in facing these new challenges. On the other hand, given the large number of applicants each year for fellowship positions in any given program, we acknowledge the potential benefit programs may obtain from limiting electronic information that is readily accessible to all applicants, as doing so may encourage applicants to communicate directly with a program and allow programs to identify candidates who are more interested.

In light of the movement to a more virtual-friendly and technology-driven fellowship application process, we identified 25 content areas that fellowships may want to include on their websites so that potential applicants can be well informed about the program before submitting an application and scheduling an interview. Efforts to improve accessibility and maximize the content of these websites may help programs attract compatible candidates, improve transparency, and guide applicants throughout the application process.

To the Editor:

Micrographic surgery and dermatologic oncology (MSDO) is a highly competitive subspecialty fellowship in dermatology. Prospective applicants often depend on the Internet to obtain pertinent information about fellowship programs to navigate the application process. An up-to-date and comprehensive fellowship website has the potential to be advantageous for both applicants and programs—applicants can more readily identify programs that align with their goals and values, and programs can effectively attract compatible applicants. These advantages are increasingly relevant with the virtual application process that has become essential considering the COVID-19 pandemic. At the height of the COVID-19 pandemic in 2020, we sought to evaluate the comprehensiveness of the content of Accreditation Council for Graduate Medical Education (ACGME) MSDO fellowship program websites to identify possible areas for improvement.

We obtained a list of all ACGME MSDO fellowships from the ACGME website (https://www.acgme.org/) and verified it against the list of MSDO programs in FREIDA, the American Medical Association residency and fellowship database (https://freida.ama-assn.org/). All programs without a website were excluded from further analysis. All data collection from currently accessible fellowship websites and evaluation occurred in April 2020.

The remaining MSDO fellowship program websites were evaluated using 25 criteria distributed among 5 domains: education/research, clinical training, program information, application process, and incentives. These criteria were determined based on earlier studies that similarly evaluated the website content of fellowship programs with inclusion of information that was considered valuable in the appraisal of fellowship programs.^1,2 Criteria were further refined by direct consideration of relevance and importance to MSDO fellowship applicants (eg, inclusion of case volume, exclusion of call schedule).

Each criterion was independently assessed by 2 investigators (J.Y.C. and S.J.E.S.). A third investigator (J.R.P.) then independently evaluated those 2 assessments for agreement. Where disagreement was discovered, the third evaluator (J.R.P.) provided a final appraisal. Cohen’s kappa (κ) was conducted to evaluate for concordance between the 2 primary website evaluators. We found there to be substantial agreement between the reviewers within the education/research (κ [SD]=0.772 [0.077]), clinical training (κ [SD]=0.740 [0.051]), application process (κ [SD]=0.726 [0.103]), and incentives domains (κ [SD]=0.730 [0.110]). There was moderate agreement (κ [SD]=0.603 [0.128]) between the reviewers within the program information domain.

We identified 77 active MSDO fellowship programs. Sixty of those 77 programs (77.9%) had a dedicated fellowship website that was readily accessible. Most programs that had a dedicated fellowship website had a core or affiliated residency program (49/60 [81.7%]).

Websites that we evaluated fulfilled a mean (SD) of 9.37 (4.17) of the 25 identified criteria. Only 13 of 60 (21.7%) websites fulfilled more than 50% of evaluated criteria.

There was no statistical difference in the number of criteria fulfilled based on whether the fellowship program had a core or affiliated residency program.

Upon reviewing website accessibility directly from FREIDA, only 5 of 60 programs (8.3%) provided applicants with a link directly to their fellowship page (Table). Most programs (41 [68.3%]) provided a link to the dermatology department website, not to the specific fellowship program page, thus requiring a multistep process to find the fellowship-specific page. The remaining programs had an inaccessible (4 [6.7%]) or absent (10 [16.7%]) link on FREIDA, though a fellowship website could be identified by an Internet search of the program name.

The domain most fulfilled was program information with an average of 51.1% of programs satisfying the criteria, whereas the incentives domain was least fulfilled with an average of only 20.8% of programs satisfying the criteria. Across the various criteria, websites more often included a description of the program (58 [96.6%]), mentioned accreditation (53 [88.3%]), and provided case descriptions (48 [80.0%]). They less often reported information regarding a fellow’s call responsibility (3 [5%]); evaluation criteria (5 [8.3%]); and rotation schedule or options (6 [10.0%]).

The highest number of criteria fulfilled by a single program was 19 (76%). The lowest number of criteria met was 2 (8%). These findings suggest a large variation in comprehensiveness across fellowship websites.

Our research suggests that many current MSDO fellowship programs have room to maximize the information provided to applicants through their websites, which is particularly relevant following the COVID-19 pandemic, as the value of providing comprehensive and transparent information through an online platform is greater than ever. Given the ongoing desire to limit travel, virtual methods for navigating the application process have been readily used, including online videoconferencing for interviews and virtual program visits. This scenario has placed applicants in a challenging situation—their ability to directly evaluate their compatibility with a given program has been limited.³

Earlier studies that analyzed rheumatology fellowship recruitment during the COVID-19 pandemic found that programs may have more difficulty highlighting the strengths of their institution (eg, clinical facilities, professional opportunities, educational environment).⁴ An updated and comprehensive fellowship website was recommended⁴ as a key part in facing these new challenges. On the other hand, given the large number of applicants each year for fellowship positions in any given program, we acknowledge the potential benefit programs may obtain from limiting electronic information that is readily accessible to all applicants, as doing so may encourage applicants to communicate directly with a program and allow programs to identify candidates who are more interested.

In light of the movement to a more virtual-friendly and technology-driven fellowship application process, we identified 25 content areas that fellowships may want to include on their websites so that potential applicants can be well informed about the program before submitting an application and scheduling an interview. Efforts to improve accessibility and maximize the content of these websites may help programs attract compatible candidates, improve transparency, and guide applicants throughout the application process.

To the Editor:

A 47-year-old man presented to the dermatology service with an asymptomatic plaque on the right thigh of 2 months’ duration. He had a medical history of HIV and Kaposi sarcoma as well as a recently relapsed primary effusion lymphoma (PEL) subsequent to an allogeneic bone marrow transplant. He initially was diagnosed with PEL 3 years prior to the current presentation during a workup for fever and weight loss. Imaging at the time demonstrated a bladder mass, which was biopsied and demonstrated PEL. Further imaging demonstrated both sinus and bone marrow involvement. Prior to dermatologic consultation, he had been treated with 6 cycles of etoposide, prednisolone, vincristine, cyclophosphamide, and doxorubicin (EPOCH); 6 cycles of brentuximab; 4 cycles of rituximab with gemcitabine and oxaliplatin; and 2 cycles of ifosfamide, carboplatin, and etoposide. Despite these therapies, he had 3 relapses, and oncology determined the need for a matched unrelated donor allogeneic stem cell transplant for his PEL.

At the time of dermatology consultation, the patient was being managed on daratumumab and bortezomib. Physical examination revealed an infiltrative plaque on the right inferomedial thigh measuring approximately 6.0 cm (largest dimension) with a small amount of peripheral scale (Figure 1). An ultrasound revealed notable subcutaneous tissue edema and increased vascularity without a discrete mass or fluid collection. A 4-mm punch biopsy demonstrated a dense infiltrate comprised of collections of histiocytes admixed with scattered plasma cells and mature lymphoid aggregates. Additionally, rare enlarged plasmablastic cells with scant basophilic cytoplasm and slightly irregular nuclear contours were visualized (Figure 2A). Immunohistochemistry was positive for CD3 with a normal CD4:CD8 ratio, CD68-highlighted histiocytes within the lymphoid aggregates, and human herpesvirus 8 (HHV-8)(or Kaposi sarcoma–associated herpesvirus) demonstrated stippled nuclear staining within the scattered large cells (Figure 2B). Epstein-Barr virus–encoded RNA staining was negative, though the area of interest was lost on deeper sectioning of the tissue block. The histopathologic findings were consistent with cutaneous extracavitary PEL. Shortly after this diagnosis, he died from disease complications.

Primary effusion lymphoma is an aggressive non-Hodgkin B-cell lymphoma that was first described by Knowles et al¹ in 1989. Primary effusion lymphoma occurs exclusively in the setting of HHV-8 infection and typically is associated with chronic immunosuppression related to HIV/AIDS. Cases that are negative for HIV-1 are rare but have been reported in organ transplant recipients and elderly men from areas with a high prevalence of HHV-8 infections. Most HIV-associated cases show concurrent Epstein-Barr virus infection, though the pathogenic meaning of this co-infection remains unclear.^2,3

Primary effusion lymphoma classically presents as an isolated effusion of malignant lymphoid cells within body cavities in the absence of solid tumor masses. The pleural, peritoneal, and pericardial spaces most commonly are involved. Extracavitary PEL, a rare variant, may present as a solid mass without effusion. In general, extracavitary tumors may occur in the setting of de novo malignancy or recurrent PEL.⁴ Cutaneous manifestations associated with extracavitary PEL are rare; 4 cases have been described in which skin lesions were the heralding sign of the disease.³ Interestingly, despite obligatory underlying HHV-8 infection, a review by Pielasinski et al³ noted only 2 patients with cutaneous PEL who had prior or concurrent Kaposi sarcoma. This heterogeneity in HHV-8–related phenotypes may be related to differences in microRNA expression, but further study is needed.⁵

The diagnosis of PEL relies on histologic, immunophenotypic, and molecular analysis of the affected tissue. The malignant cells typically are large with round to irregular nuclei. These cells may demonstrate a variety of appearances, including anaplastic, plasmablastic, and immunoblastic morphologies.^6,7 The immunophenotype displays CD45 positivity and markers of lymphocyte activation (CD30, CD38, CD71), while typical B-cell (CD19, CD20, CD79a) and T-cell (CD3, CD4, CD8) markers often are absent.^6-8 Human herpesvirus 8 detection by polymerase chain reaction testing of the peripheral blood or by immunohistochemistry staining of the affected tissue is required for diagnosis.^6,7 Epstein-Barr virus infection may be detected via in situ hybridization, though it is not required for diagnosis.

The overall prognosis for PEL is poor; Brimo et al⁶ reported a median survival of less than 6 months, and Guillet et al⁹ reported 5-year overall survival (OS) for PEL vs extracavitary PEL to be 43% vs 39%. Another review noted variation in survival contingent on the number of body cavities involved; patients with a single body cavity involved experienced a median OS of 18 months, whereas patients with multiple involved cavities experienced a median OS of 4 months,⁷ possibly due to the limited study of treatment regimens or disease aggressiveness. Even in cases of successful initial treatment, relapse within 6 to 8 months is common. Extracavitary PEL may have improved disease-free survival relative to classic PEL, though the data were less clear for OS.⁹ Limitations of the Guillet et al⁹ study included a small sample size, the impossibility to randomize to disease type, and loss of power on the log-rank test for OS in the setting of possible nonproportional hazards (crossing survival curves). Overall, prognostic differences between the groups may be challenging to ascertain until further data are obtained.

As with many HIV-associated neoplasms, antiretroviral treatment (ART) for HIV-positive patients affords a better prognosis when used in addition to therapy directed at malignancy.⁷ The general approach is for concurrent ART with systemic therapies such as rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone for the rare CD20⁺ cases, and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or dose-adjusted EPOCH therapy in the more common CD20⁻ PEL cases. Narkhede et al⁷ suggested avoidance of methotrexate in patients with effusions because of increased toxicity, but it is unclear if this recommendation is applicable in extracavitary PEL patients without an effusion. Additionally, second-line treatment modalities include radiation for solid PEL masses, HHV-8–targeted antivirals, and stem cell transplantation, though evidence is limited. Of note, there is a phase I-II trial (ClinicalTrials.gov identifier NCT02911142) ongoing for treatment-naïve PEL patients involving the experimental treatment DA-EPOCH-R plus lenalidomide, but the trial is ongoing.¹⁰

We report a case of cutaneous PEL in a patient with a history of Kaposi sarcoma. The patient’s deterioration and ultimate death despite initial treatment with EPOCH and bone marrow transplantation followed by final management with daratumumab and bortezomib confirm other reports that PEL has a poor prognosis and that optimal treatments are not well delineated for these patients. In general, the current approach is to utilize ART for HIV-positive patients and to then implement chemotherapy such as CHOP. Without continued research and careful planning of treatments, data will remain limited on how best to serve patients with PEL.

To the Editor:

A 47-year-old man presented to the dermatology service with an asymptomatic plaque on the right thigh of 2 months’ duration. He had a medical history of HIV and Kaposi sarcoma as well as a recently relapsed primary effusion lymphoma (PEL) subsequent to an allogeneic bone marrow transplant. He initially was diagnosed with PEL 3 years prior to the current presentation during a workup for fever and weight loss. Imaging at the time demonstrated a bladder mass, which was biopsied and demonstrated PEL. Further imaging demonstrated both sinus and bone marrow involvement. Prior to dermatologic consultation, he had been treated with 6 cycles of etoposide, prednisolone, vincristine, cyclophosphamide, and doxorubicin (EPOCH); 6 cycles of brentuximab; 4 cycles of rituximab with gemcitabine and oxaliplatin; and 2 cycles of ifosfamide, carboplatin, and etoposide. Despite these therapies, he had 3 relapses, and oncology determined the need for a matched unrelated donor allogeneic stem cell transplant for his PEL.

At the time of dermatology consultation, the patient was being managed on daratumumab and bortezomib. Physical examination revealed an infiltrative plaque on the right inferomedial thigh measuring approximately 6.0 cm (largest dimension) with a small amount of peripheral scale (Figure 1). An ultrasound revealed notable subcutaneous tissue edema and increased vascularity without a discrete mass or fluid collection. A 4-mm punch biopsy demonstrated a dense infiltrate comprised of collections of histiocytes admixed with scattered plasma cells and mature lymphoid aggregates. Additionally, rare enlarged plasmablastic cells with scant basophilic cytoplasm and slightly irregular nuclear contours were visualized (Figure 2A). Immunohistochemistry was positive for CD3 with a normal CD4:CD8 ratio, CD68-highlighted histiocytes within the lymphoid aggregates, and human herpesvirus 8 (HHV-8)(or Kaposi sarcoma–associated herpesvirus) demonstrated stippled nuclear staining within the scattered large cells (Figure 2B). Epstein-Barr virus–encoded RNA staining was negative, though the area of interest was lost on deeper sectioning of the tissue block. The histopathologic findings were consistent with cutaneous extracavitary PEL. Shortly after this diagnosis, he died from disease complications.

Primary effusion lymphoma is an aggressive non-Hodgkin B-cell lymphoma that was first described by Knowles et al¹ in 1989. Primary effusion lymphoma occurs exclusively in the setting of HHV-8 infection and typically is associated with chronic immunosuppression related to HIV/AIDS. Cases that are negative for HIV-1 are rare but have been reported in organ transplant recipients and elderly men from areas with a high prevalence of HHV-8 infections. Most HIV-associated cases show concurrent Epstein-Barr virus infection, though the pathogenic meaning of this co-infection remains unclear.^2,3

Primary effusion lymphoma classically presents as an isolated effusion of malignant lymphoid cells within body cavities in the absence of solid tumor masses. The pleural, peritoneal, and pericardial spaces most commonly are involved. Extracavitary PEL, a rare variant, may present as a solid mass without effusion. In general, extracavitary tumors may occur in the setting of de novo malignancy or recurrent PEL.⁴ Cutaneous manifestations associated with extracavitary PEL are rare; 4 cases have been described in which skin lesions were the heralding sign of the disease.³ Interestingly, despite obligatory underlying HHV-8 infection, a review by Pielasinski et al³ noted only 2 patients with cutaneous PEL who had prior or concurrent Kaposi sarcoma. This heterogeneity in HHV-8–related phenotypes may be related to differences in microRNA expression, but further study is needed.⁵

The diagnosis of PEL relies on histologic, immunophenotypic, and molecular analysis of the affected tissue. The malignant cells typically are large with round to irregular nuclei. These cells may demonstrate a variety of appearances, including anaplastic, plasmablastic, and immunoblastic morphologies.^6,7 The immunophenotype displays CD45 positivity and markers of lymphocyte activation (CD30, CD38, CD71), while typical B-cell (CD19, CD20, CD79a) and T-cell (CD3, CD4, CD8) markers often are absent.^6-8 Human herpesvirus 8 detection by polymerase chain reaction testing of the peripheral blood or by immunohistochemistry staining of the affected tissue is required for diagnosis.^6,7 Epstein-Barr virus infection may be detected via in situ hybridization, though it is not required for diagnosis.

The overall prognosis for PEL is poor; Brimo et al⁶ reported a median survival of less than 6 months, and Guillet et al⁹ reported 5-year overall survival (OS) for PEL vs extracavitary PEL to be 43% vs 39%. Another review noted variation in survival contingent on the number of body cavities involved; patients with a single body cavity involved experienced a median OS of 18 months, whereas patients with multiple involved cavities experienced a median OS of 4 months,⁷ possibly due to the limited study of treatment regimens or disease aggressiveness. Even in cases of successful initial treatment, relapse within 6 to 8 months is common. Extracavitary PEL may have improved disease-free survival relative to classic PEL, though the data were less clear for OS.⁹ Limitations of the Guillet et al⁹ study included a small sample size, the impossibility to randomize to disease type, and loss of power on the log-rank test for OS in the setting of possible nonproportional hazards (crossing survival curves). Overall, prognostic differences between the groups may be challenging to ascertain until further data are obtained.

As with many HIV-associated neoplasms, antiretroviral treatment (ART) for HIV-positive patients affords a better prognosis when used in addition to therapy directed at malignancy.⁷ The general approach is for concurrent ART with systemic therapies such as rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone for the rare CD20⁺ cases, and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or dose-adjusted EPOCH therapy in the more common CD20⁻ PEL cases. Narkhede et al⁷ suggested avoidance of methotrexate in patients with effusions because of increased toxicity, but it is unclear if this recommendation is applicable in extracavitary PEL patients without an effusion. Additionally, second-line treatment modalities include radiation for solid PEL masses, HHV-8–targeted antivirals, and stem cell transplantation, though evidence is limited. Of note, there is a phase I-II trial (ClinicalTrials.gov identifier NCT02911142) ongoing for treatment-naïve PEL patients involving the experimental treatment DA-EPOCH-R plus lenalidomide, but the trial is ongoing.¹⁰

We report a case of cutaneous PEL in a patient with a history of Kaposi sarcoma. The patient’s deterioration and ultimate death despite initial treatment with EPOCH and bone marrow transplantation followed by final management with daratumumab and bortezomib confirm other reports that PEL has a poor prognosis and that optimal treatments are not well delineated for these patients. In general, the current approach is to utilize ART for HIV-positive patients and to then implement chemotherapy such as CHOP. Without continued research and careful planning of treatments, data will remain limited on how best to serve patients with PEL.

To the Editor:

A 47-year-old man presented to the dermatology service with an asymptomatic plaque on the right thigh of 2 months’ duration. He had a medical history of HIV and Kaposi sarcoma as well as a recently relapsed primary effusion lymphoma (PEL) subsequent to an allogeneic bone marrow transplant. He initially was diagnosed with PEL 3 years prior to the current presentation during a workup for fever and weight loss. Imaging at the time demonstrated a bladder mass, which was biopsied and demonstrated PEL. Further imaging demonstrated both sinus and bone marrow involvement. Prior to dermatologic consultation, he had been treated with 6 cycles of etoposide, prednisolone, vincristine, cyclophosphamide, and doxorubicin (EPOCH); 6 cycles of brentuximab; 4 cycles of rituximab with gemcitabine and oxaliplatin; and 2 cycles of ifosfamide, carboplatin, and etoposide. Despite these therapies, he had 3 relapses, and oncology determined the need for a matched unrelated donor allogeneic stem cell transplant for his PEL.

At the time of dermatology consultation, the patient was being managed on daratumumab and bortezomib. Physical examination revealed an infiltrative plaque on the right inferomedial thigh measuring approximately 6.0 cm (largest dimension) with a small amount of peripheral scale (Figure 1). An ultrasound revealed notable subcutaneous tissue edema and increased vascularity without a discrete mass or fluid collection. A 4-mm punch biopsy demonstrated a dense infiltrate comprised of collections of histiocytes admixed with scattered plasma cells and mature lymphoid aggregates. Additionally, rare enlarged plasmablastic cells with scant basophilic cytoplasm and slightly irregular nuclear contours were visualized (Figure 2A). Immunohistochemistry was positive for CD3 with a normal CD4:CD8 ratio, CD68-highlighted histiocytes within the lymphoid aggregates, and human herpesvirus 8 (HHV-8)(or Kaposi sarcoma–associated herpesvirus) demonstrated stippled nuclear staining within the scattered large cells (Figure 2B). Epstein-Barr virus–encoded RNA staining was negative, though the area of interest was lost on deeper sectioning of the tissue block. The histopathologic findings were consistent with cutaneous extracavitary PEL. Shortly after this diagnosis, he died from disease complications.

Primary effusion lymphoma is an aggressive non-Hodgkin B-cell lymphoma that was first described by Knowles et al¹ in 1989. Primary effusion lymphoma occurs exclusively in the setting of HHV-8 infection and typically is associated with chronic immunosuppression related to HIV/AIDS. Cases that are negative for HIV-1 are rare but have been reported in organ transplant recipients and elderly men from areas with a high prevalence of HHV-8 infections. Most HIV-associated cases show concurrent Epstein-Barr virus infection, though the pathogenic meaning of this co-infection remains unclear.^2,3

Primary effusion lymphoma classically presents as an isolated effusion of malignant lymphoid cells within body cavities in the absence of solid tumor masses. The pleural, peritoneal, and pericardial spaces most commonly are involved. Extracavitary PEL, a rare variant, may present as a solid mass without effusion. In general, extracavitary tumors may occur in the setting of de novo malignancy or recurrent PEL.⁴ Cutaneous manifestations associated with extracavitary PEL are rare; 4 cases have been described in which skin lesions were the heralding sign of the disease.³ Interestingly, despite obligatory underlying HHV-8 infection, a review by Pielasinski et al³ noted only 2 patients with cutaneous PEL who had prior or concurrent Kaposi sarcoma. This heterogeneity in HHV-8–related phenotypes may be related to differences in microRNA expression, but further study is needed.⁵

The diagnosis of PEL relies on histologic, immunophenotypic, and molecular analysis of the affected tissue. The malignant cells typically are large with round to irregular nuclei. These cells may demonstrate a variety of appearances, including anaplastic, plasmablastic, and immunoblastic morphologies.^6,7 The immunophenotype displays CD45 positivity and markers of lymphocyte activation (CD30, CD38, CD71), while typical B-cell (CD19, CD20, CD79a) and T-cell (CD3, CD4, CD8) markers often are absent.^6-8 Human herpesvirus 8 detection by polymerase chain reaction testing of the peripheral blood or by immunohistochemistry staining of the affected tissue is required for diagnosis.^6,7 Epstein-Barr virus infection may be detected via in situ hybridization, though it is not required for diagnosis.

The overall prognosis for PEL is poor; Brimo et al⁶ reported a median survival of less than 6 months, and Guillet et al⁹ reported 5-year overall survival (OS) for PEL vs extracavitary PEL to be 43% vs 39%. Another review noted variation in survival contingent on the number of body cavities involved; patients with a single body cavity involved experienced a median OS of 18 months, whereas patients with multiple involved cavities experienced a median OS of 4 months,⁷ possibly due to the limited study of treatment regimens or disease aggressiveness. Even in cases of successful initial treatment, relapse within 6 to 8 months is common. Extracavitary PEL may have improved disease-free survival relative to classic PEL, though the data were less clear for OS.⁹ Limitations of the Guillet et al⁹ study included a small sample size, the impossibility to randomize to disease type, and loss of power on the log-rank test for OS in the setting of possible nonproportional hazards (crossing survival curves). Overall, prognostic differences between the groups may be challenging to ascertain until further data are obtained.

As with many HIV-associated neoplasms, antiretroviral treatment (ART) for HIV-positive patients affords a better prognosis when used in addition to therapy directed at malignancy.⁷ The general approach is for concurrent ART with systemic therapies such as rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone for the rare CD20⁺ cases, and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or dose-adjusted EPOCH therapy in the more common CD20⁻ PEL cases. Narkhede et al⁷ suggested avoidance of methotrexate in patients with effusions because of increased toxicity, but it is unclear if this recommendation is applicable in extracavitary PEL patients without an effusion. Additionally, second-line treatment modalities include radiation for solid PEL masses, HHV-8–targeted antivirals, and stem cell transplantation, though evidence is limited. Of note, there is a phase I-II trial (ClinicalTrials.gov identifier NCT02911142) ongoing for treatment-naïve PEL patients involving the experimental treatment DA-EPOCH-R plus lenalidomide, but the trial is ongoing.¹⁰

We report a case of cutaneous PEL in a patient with a history of Kaposi sarcoma. The patient’s deterioration and ultimate death despite initial treatment with EPOCH and bone marrow transplantation followed by final management with daratumumab and bortezomib confirm other reports that PEL has a poor prognosis and that optimal treatments are not well delineated for these patients. In general, the current approach is to utilize ART for HIV-positive patients and to then implement chemotherapy such as CHOP. Without continued research and careful planning of treatments, data will remain limited on how best to serve patients with PEL.

The Diagnosis: Erythropoietic Protoporphyria 

Erythropoietic protoporphyria (EPP) is an autosomal-recessive photodermatosis that results from loss of activity of ferrochelatase, the last enzyme in the heme biosynthetic pathway.¹ Erythropoietic protoporphyria normally involves sun-exposed areas of the body. Skin that is exposed to sunlight develops intense burning and stinging pain followed by erythema, edema, crusting, and petechiae that develops into waxy scarring over time. In contrast to other porphyrias, blistering generally is not seen.² Accurate diagnosis often can be delayed by a decade or more following symptom onset due to the prominence of subjective pain as the presenting sign.  

The histologic appearance of EPP differs depending on the chronicity of lesions. Biopsies of acute lesions show vacuolization of epidermal cells with intercellular edema, vacuolization and cytolysis of endothelial cells in superficial blood vessels, and focal red blood cell extravasation.^3,4 A largely neutrophilic inflammatory infiltrate can be present.⁵ Hyaline cuffing develops over time in and around vessels in the papillary and superficial reticular dermis with notable sparing of adnexal structures. The perivascular deposits are strongly periodic acid-Schiff (PAS) positive and diastase resistant (Figure 1). Direct immunofluorescence shows mainly IgG and some IgM, fibrinogen, and C3 outlining characteristic donut-shaped blood vessels in the papillary dermis.⁶ The prominent thickness of the perivascular hyaline material depositions and the absence of subepidermal blistering can help differentiate EPP from porphyria cutanea tarda (PCT) and pseudoporphyria.^6,7 When the deposition is extensive and involves the surrounding dermis, EPP can mimic colloid milium. Additional histologic differential diagnoses of EPP include other dermal depositional diseases such as lipoid proteinosis and amyloidosis.  

Lipoid proteinosis is an autosomal-recessive multisystem genodermatosis caused by mutations in extracellular matrix gene 1, ECM1. The first clinical sign can be a hoarse cry in infancy due to infiltration of vocal cords.³ Development of papulonodular lesions along the eyelids can result in a string-of-beads appearance called moniliform blepharosis, which is pathognomonic for lipoid proteinosis.⁶ With chronicity, the involved skin can become yellow, waxy, and thickened, particularly in the flexures or areas of trauma. Histologically, the dermis in lipoid proteinosis becomes diffusely thickened due to deposition of PAS-positive eosinophilic hyaline material that stains weakly with Congo red and thioflavin T.⁶ Early lesions demonstrate pale pink, hyalinelike thickening of the papillary dermal capillaries. Chronic lesions reveal an acanthotic epidermis, occasional papillomatosis with overlying hyperkeratosis, and a thickened dermis where diffuse thick bundles of pink hyaline deposits are oriented perpendicularly to the dermoepidermal junction.^1,6 Lipoid proteinosis can be differentiated from EPP by the involvement of adnexal structures such as hair follicles, sebaceous glands, and arrector pili muscles (Figure 2), as opposed to EPP where adnexal structures are spared.¹ Additionally, depositions in lipoid proteinosis are centered around both superficial and deep vessels with an onion skin-like pattern, while EPP involves mainly superficial vessels with more mild and focal hyalinization.

Juvenile colloid milium (JCM) is a rare condition that presents before puberty with discrete, yellow-brown, translucent papules predominantly located on the cheeks and nose and around the mouth. A gelatinous material can be expressed after puncturing a lesion.⁶ Gingival deposits and ligneous conjunctivitis also can be present. On histopathology, JCM shows degeneration of epidermal keratinocytes that form colloid bodies within the superficial dermis following apoptosis.⁶ Hematoxylin and eosin staining shows amorphous, fissured, pale pink deposits completely filling and expanding the superficial to mid dermis with clefting and no inflammation (Figure 3). Spindle-shaped fibroblasts may be seen within the lines of colloid fissuring and dispersed throughout the deposits.¹ Histologically, JCM can be differentiated from EPP because deposits in EPP are distributed around and within superficial blood vessel walls, causing prominent vascular thickening not seen in JCM.⁶ The adult variant of colloid milium also can be distinguished from EPP by the presence of solar elastosis, which is absent in EPP due to a history of sun avoidance.^3,7  

Lichen amyloidosis presents with highly pruritic, red-brown, hyperkeratotic papules that commonly are found on the anterior lower legs and extensor forearms.¹ The calves, ankles, dorsal aspects of the feet, thighs, and trunk also may be affected. Excoriations, lichenification, and nodular prurigo-like lesions due to chronic scratching can be present.⁶ Lichen amyloidosis is characterized by large, pink, amorphous deposits in the papillary dermis with epidermal acanthosis, hypergranulosis, and hyperkeratosis (Figure 4).⁶ Perivascular deposits are not a feature of primary cutaneous localized amyloid lesions.⁶ The diagnosis can be confirmed with Congo red staining under polarized light, which classically demonstrates apple green birefringence.¹ For cases of amyloid that are not detected by Congo red or are not clear-cut, direct immunofluorescence and immunohistochemistry can be used as adjuncts for diagnosis. Amyloid deposits fluoresce positively for immunoglobulins or complements, particularly IgM and C3,⁸ and immunohistochemistry confirms the presence of keratin epitopes in deposits.⁹  

Porphyria cutanea tarda can appear histologically similar to EPP. Caterpillar bodies, or linearly arranged eosinophilic PAS-positive globules in the epidermis overlying subepidermal bullae, are a diagnostic histopathologic finding in both PCT and EPP but are seen in less than half of both cases.^7,10 Compared to EPP, the perivascular deposits in PCT typically are less pronounced and limited to the vessel wall with smaller hyaline cuffs (Figure 5).⁷ Additionally, solar elastosis can be seen in PCT lesions but not in EPP, as patients with PCT tend to be older and have increased cumulative sun damage.  

The Diagnosis: Erythropoietic Protoporphyria 

Erythropoietic protoporphyria (EPP) is an autosomal-recessive photodermatosis that results from loss of activity of ferrochelatase, the last enzyme in the heme biosynthetic pathway.¹ Erythropoietic protoporphyria normally involves sun-exposed areas of the body. Skin that is exposed to sunlight develops intense burning and stinging pain followed by erythema, edema, crusting, and petechiae that develops into waxy scarring over time. In contrast to other porphyrias, blistering generally is not seen.² Accurate diagnosis often can be delayed by a decade or more following symptom onset due to the prominence of subjective pain as the presenting sign.  

The histologic appearance of EPP differs depending on the chronicity of lesions. Biopsies of acute lesions show vacuolization of epidermal cells with intercellular edema, vacuolization and cytolysis of endothelial cells in superficial blood vessels, and focal red blood cell extravasation.^3,4 A largely neutrophilic inflammatory infiltrate can be present.⁵ Hyaline cuffing develops over time in and around vessels in the papillary and superficial reticular dermis with notable sparing of adnexal structures. The perivascular deposits are strongly periodic acid-Schiff (PAS) positive and diastase resistant (Figure 1). Direct immunofluorescence shows mainly IgG and some IgM, fibrinogen, and C3 outlining characteristic donut-shaped blood vessels in the papillary dermis.⁶ The prominent thickness of the perivascular hyaline material depositions and the absence of subepidermal blistering can help differentiate EPP from porphyria cutanea tarda (PCT) and pseudoporphyria.^6,7 When the deposition is extensive and involves the surrounding dermis, EPP can mimic colloid milium. Additional histologic differential diagnoses of EPP include other dermal depositional diseases such as lipoid proteinosis and amyloidosis.  

Lipoid proteinosis is an autosomal-recessive multisystem genodermatosis caused by mutations in extracellular matrix gene 1, ECM1. The first clinical sign can be a hoarse cry in infancy due to infiltration of vocal cords.³ Development of papulonodular lesions along the eyelids can result in a string-of-beads appearance called moniliform blepharosis, which is pathognomonic for lipoid proteinosis.⁶ With chronicity, the involved skin can become yellow, waxy, and thickened, particularly in the flexures or areas of trauma. Histologically, the dermis in lipoid proteinosis becomes diffusely thickened due to deposition of PAS-positive eosinophilic hyaline material that stains weakly with Congo red and thioflavin T.⁶ Early lesions demonstrate pale pink, hyalinelike thickening of the papillary dermal capillaries. Chronic lesions reveal an acanthotic epidermis, occasional papillomatosis with overlying hyperkeratosis, and a thickened dermis where diffuse thick bundles of pink hyaline deposits are oriented perpendicularly to the dermoepidermal junction.^1,6 Lipoid proteinosis can be differentiated from EPP by the involvement of adnexal structures such as hair follicles, sebaceous glands, and arrector pili muscles (Figure 2), as opposed to EPP where adnexal structures are spared.¹ Additionally, depositions in lipoid proteinosis are centered around both superficial and deep vessels with an onion skin-like pattern, while EPP involves mainly superficial vessels with more mild and focal hyalinization.

Juvenile colloid milium (JCM) is a rare condition that presents before puberty with discrete, yellow-brown, translucent papules predominantly located on the cheeks and nose and around the mouth. A gelatinous material can be expressed after puncturing a lesion.⁶ Gingival deposits and ligneous conjunctivitis also can be present. On histopathology, JCM shows degeneration of epidermal keratinocytes that form colloid bodies within the superficial dermis following apoptosis.⁶ Hematoxylin and eosin staining shows amorphous, fissured, pale pink deposits completely filling and expanding the superficial to mid dermis with clefting and no inflammation (Figure 3). Spindle-shaped fibroblasts may be seen within the lines of colloid fissuring and dispersed throughout the deposits.¹ Histologically, JCM can be differentiated from EPP because deposits in EPP are distributed around and within superficial blood vessel walls, causing prominent vascular thickening not seen in JCM.⁶ The adult variant of colloid milium also can be distinguished from EPP by the presence of solar elastosis, which is absent in EPP due to a history of sun avoidance.^3,7  

Lichen amyloidosis presents with highly pruritic, red-brown, hyperkeratotic papules that commonly are found on the anterior lower legs and extensor forearms.¹ The calves, ankles, dorsal aspects of the feet, thighs, and trunk also may be affected. Excoriations, lichenification, and nodular prurigo-like lesions due to chronic scratching can be present.⁶ Lichen amyloidosis is characterized by large, pink, amorphous deposits in the papillary dermis with epidermal acanthosis, hypergranulosis, and hyperkeratosis (Figure 4).⁶ Perivascular deposits are not a feature of primary cutaneous localized amyloid lesions.⁶ The diagnosis can be confirmed with Congo red staining under polarized light, which classically demonstrates apple green birefringence.¹ For cases of amyloid that are not detected by Congo red or are not clear-cut, direct immunofluorescence and immunohistochemistry can be used as adjuncts for diagnosis. Amyloid deposits fluoresce positively for immunoglobulins or complements, particularly IgM and C3,⁸ and immunohistochemistry confirms the presence of keratin epitopes in deposits.⁹  

Porphyria cutanea tarda can appear histologically similar to EPP. Caterpillar bodies, or linearly arranged eosinophilic PAS-positive globules in the epidermis overlying subepidermal bullae, are a diagnostic histopathologic finding in both PCT and EPP but are seen in less than half of both cases.^7,10 Compared to EPP, the perivascular deposits in PCT typically are less pronounced and limited to the vessel wall with smaller hyaline cuffs (Figure 5).⁷ Additionally, solar elastosis can be seen in PCT lesions but not in EPP, as patients with PCT tend to be older and have increased cumulative sun damage.  

The Diagnosis: Erythropoietic Protoporphyria 

Erythropoietic protoporphyria (EPP) is an autosomal-recessive photodermatosis that results from loss of activity of ferrochelatase, the last enzyme in the heme biosynthetic pathway.¹ Erythropoietic protoporphyria normally involves sun-exposed areas of the body. Skin that is exposed to sunlight develops intense burning and stinging pain followed by erythema, edema, crusting, and petechiae that develops into waxy scarring over time. In contrast to other porphyrias, blistering generally is not seen.² Accurate diagnosis often can be delayed by a decade or more following symptom onset due to the prominence of subjective pain as the presenting sign.  

The histologic appearance of EPP differs depending on the chronicity of lesions. Biopsies of acute lesions show vacuolization of epidermal cells with intercellular edema, vacuolization and cytolysis of endothelial cells in superficial blood vessels, and focal red blood cell extravasation.^3,4 A largely neutrophilic inflammatory infiltrate can be present.⁵ Hyaline cuffing develops over time in and around vessels in the papillary and superficial reticular dermis with notable sparing of adnexal structures. The perivascular deposits are strongly periodic acid-Schiff (PAS) positive and diastase resistant (Figure 1). Direct immunofluorescence shows mainly IgG and some IgM, fibrinogen, and C3 outlining characteristic donut-shaped blood vessels in the papillary dermis.⁶ The prominent thickness of the perivascular hyaline material depositions and the absence of subepidermal blistering can help differentiate EPP from porphyria cutanea tarda (PCT) and pseudoporphyria.^6,7 When the deposition is extensive and involves the surrounding dermis, EPP can mimic colloid milium. Additional histologic differential diagnoses of EPP include other dermal depositional diseases such as lipoid proteinosis and amyloidosis.  

Lipoid proteinosis is an autosomal-recessive multisystem genodermatosis caused by mutations in extracellular matrix gene 1, ECM1. The first clinical sign can be a hoarse cry in infancy due to infiltration of vocal cords.³ Development of papulonodular lesions along the eyelids can result in a string-of-beads appearance called moniliform blepharosis, which is pathognomonic for lipoid proteinosis.⁶ With chronicity, the involved skin can become yellow, waxy, and thickened, particularly in the flexures or areas of trauma. Histologically, the dermis in lipoid proteinosis becomes diffusely thickened due to deposition of PAS-positive eosinophilic hyaline material that stains weakly with Congo red and thioflavin T.⁶ Early lesions demonstrate pale pink, hyalinelike thickening of the papillary dermal capillaries. Chronic lesions reveal an acanthotic epidermis, occasional papillomatosis with overlying hyperkeratosis, and a thickened dermis where diffuse thick bundles of pink hyaline deposits are oriented perpendicularly to the dermoepidermal junction.^1,6 Lipoid proteinosis can be differentiated from EPP by the involvement of adnexal structures such as hair follicles, sebaceous glands, and arrector pili muscles (Figure 2), as opposed to EPP where adnexal structures are spared.¹ Additionally, depositions in lipoid proteinosis are centered around both superficial and deep vessels with an onion skin-like pattern, while EPP involves mainly superficial vessels with more mild and focal hyalinization.

Juvenile colloid milium (JCM) is a rare condition that presents before puberty with discrete, yellow-brown, translucent papules predominantly located on the cheeks and nose and around the mouth. A gelatinous material can be expressed after puncturing a lesion.⁶ Gingival deposits and ligneous conjunctivitis also can be present. On histopathology, JCM shows degeneration of epidermal keratinocytes that form colloid bodies within the superficial dermis following apoptosis.⁶ Hematoxylin and eosin staining shows amorphous, fissured, pale pink deposits completely filling and expanding the superficial to mid dermis with clefting and no inflammation (Figure 3). Spindle-shaped fibroblasts may be seen within the lines of colloid fissuring and dispersed throughout the deposits.¹ Histologically, JCM can be differentiated from EPP because deposits in EPP are distributed around and within superficial blood vessel walls, causing prominent vascular thickening not seen in JCM.⁶ The adult variant of colloid milium also can be distinguished from EPP by the presence of solar elastosis, which is absent in EPP due to a history of sun avoidance.^3,7  

Lichen amyloidosis presents with highly pruritic, red-brown, hyperkeratotic papules that commonly are found on the anterior lower legs and extensor forearms.¹ The calves, ankles, dorsal aspects of the feet, thighs, and trunk also may be affected. Excoriations, lichenification, and nodular prurigo-like lesions due to chronic scratching can be present.⁶ Lichen amyloidosis is characterized by large, pink, amorphous deposits in the papillary dermis with epidermal acanthosis, hypergranulosis, and hyperkeratosis (Figure 4).⁶ Perivascular deposits are not a feature of primary cutaneous localized amyloid lesions.⁶ The diagnosis can be confirmed with Congo red staining under polarized light, which classically demonstrates apple green birefringence.¹ For cases of amyloid that are not detected by Congo red or are not clear-cut, direct immunofluorescence and immunohistochemistry can be used as adjuncts for diagnosis. Amyloid deposits fluoresce positively for immunoglobulins or complements, particularly IgM and C3,⁸ and immunohistochemistry confirms the presence of keratin epitopes in deposits.⁹  

Porphyria cutanea tarda can appear histologically similar to EPP. Caterpillar bodies, or linearly arranged eosinophilic PAS-positive globules in the epidermis overlying subepidermal bullae, are a diagnostic histopathologic finding in both PCT and EPP but are seen in less than half of both cases.^7,10 Compared to EPP, the perivascular deposits in PCT typically are less pronounced and limited to the vessel wall with smaller hyaline cuffs (Figure 5).⁷ Additionally, solar elastosis can be seen in PCT lesions but not in EPP, as patients with PCT tend to be older and have increased cumulative sun damage.