Dermatopathology

The Diagnosis: Primary Cutaneous Anaplastic Large Cell Lymphoma  

Microscopic analysis showed a dense proliferation of mononuclear cells filling and expanding the dermis with focal epidermotropism (Figure 1). Immunohistochemistry demonstrated strong and diffuse staining for CD3, CD4, and CD30 (Figure 2) and lack of staining for anaplastic lymphoma kinase (ALK). Workup to exclude systemic disease was initiated and included unremarkable computed tomography (CT) of the neck, chest, abdomen, and pelvis along with no abnormal cells on bone marrow biopsy. Complete blood cell count, basic metabolic panel, and lactate dehydrogenase were within reference range. Given the lack of evidence for systemic involvement, a diagnosis of primary cutaneous anaplastic large cell lymphoma (PC-ALCL) was made. The treatment plan for our patient with a solitary lesion was localized radiation therapy. 

Primary cutaneous CD30⁺ lymphoproliferative disorders encompass a spectrum of conditions, with premalignant lymphomatoid papulosis (LyP) at one extreme and the malignant PC-ALCL on the other.¹ The diagnosis of PC-ALCL is made by clinicopathologic correlation, and lesions typically present abruptly as solitary or grouped nodules with a tendency to ulcerate over time. Spontaneous regression has been reported, but relapse in the skin is frequent.² 

A representative, typically excisional, biopsy should be performed if the clinician suspects PC-ALCL. Histologic criteria include a dense dermal infiltrate of large pleomorphic cells and the expression of CD30 in at least 75% of tumor cells.³ Primary cutaneous anaplastic large cell lymphoma typically lacks the ALK gene translocation with the nucleophosmin gene, NPM, that is common in systemic disease; however, a small subset of PC-ALCL may be ALK positive and indicate a higher chance of transformation into systemic disease.²

 The extent of the lymphoma should be staged to exclude the possibility of systemic disease. This assessment includes a complete physical examination; laboratory investigation, including complete blood cell count with differential and blood chemistries; and radiography. A positron emission tomography-CT scan of the neck, chest, abdomen, and pelvis, or a whole-body integrated positron emission tomography-CT are sufficient for the radiographic examination.³ 

The initial choice of treatment for solitary or localized PC-ALCL is localized radiation therapy or low-dose methotrexate. Targeted therapy such as brentuximab has been shown to be effective for those with multifocal systemic involvement or refractory disease.² Cure rates from radiation therapy alone approach 95%.³ It is important to highlight radiation therapy as the initial management plan to increase awareness and to avoid inappropriate treatment of PC-ALCL with traditional chemotherapy. 

Large lesions of LyP may appear similar to PC-ALCL on histopathology, making the two entities difficult to distinguish. However, in contrast to PC-ALCL, LyP classically has a different clinical course characterized by waxing and waning crops of lesions that typically are smaller (<1 cm) than those of PC-ALCL.² Large cell transformation of mycosis fungoides is another entity to consider, but these patients usually have a known history of mycosis fungoides.⁴ 

Keratoacanthomas, considered to be a variant of a well-differentiated squamous cell carcinoma, present as rapidly enlarging crateriform nodules with a keratotic core. They usually are found on the head and neck or sun-exposed areas of the extremities and may regress spontaneously.⁵ Histology will show atypical, highly differentiated squamous epithelia. Merkel cell carcinoma also has a predilection for the head and neck in older patients and may present as a rapidly growing nodule. However, histology will show an aggressive tumor with small round blue cells, and immunohistochemistry will show the characteristic paranuclear dot staining for CK20 along with staining for various neuroendocrine markers. Similarly, atypical fibroxanthoma is a low-grade sarcoma that also presents on the head and neck of elderly sun-damaged patients.⁵ Histology will show dermal proliferation of spindle cells that often extend up against the epidermis along with pleomorphism and atypical mitoses. Basal cell carcinoma is a common tumor that can present on the head and neck in sun-damaged patients. Nodular basal cell carcinomas can enlarge and ulcerate, but growth is seen over years rather than weeks.⁵ Histology characteristically will show tumor islands composed of basaloid cells with peripheral palisading and clefting between the tumor islands and the stroma.  

The Diagnosis: Primary Cutaneous Anaplastic Large Cell Lymphoma  

Microscopic analysis showed a dense proliferation of mononuclear cells filling and expanding the dermis with focal epidermotropism (Figure 1). Immunohistochemistry demonstrated strong and diffuse staining for CD3, CD4, and CD30 (Figure 2) and lack of staining for anaplastic lymphoma kinase (ALK). Workup to exclude systemic disease was initiated and included unremarkable computed tomography (CT) of the neck, chest, abdomen, and pelvis along with no abnormal cells on bone marrow biopsy. Complete blood cell count, basic metabolic panel, and lactate dehydrogenase were within reference range. Given the lack of evidence for systemic involvement, a diagnosis of primary cutaneous anaplastic large cell lymphoma (PC-ALCL) was made. The treatment plan for our patient with a solitary lesion was localized radiation therapy. 

Primary cutaneous CD30⁺ lymphoproliferative disorders encompass a spectrum of conditions, with premalignant lymphomatoid papulosis (LyP) at one extreme and the malignant PC-ALCL on the other.¹ The diagnosis of PC-ALCL is made by clinicopathologic correlation, and lesions typically present abruptly as solitary or grouped nodules with a tendency to ulcerate over time. Spontaneous regression has been reported, but relapse in the skin is frequent.² 

A representative, typically excisional, biopsy should be performed if the clinician suspects PC-ALCL. Histologic criteria include a dense dermal infiltrate of large pleomorphic cells and the expression of CD30 in at least 75% of tumor cells.³ Primary cutaneous anaplastic large cell lymphoma typically lacks the ALK gene translocation with the nucleophosmin gene, NPM, that is common in systemic disease; however, a small subset of PC-ALCL may be ALK positive and indicate a higher chance of transformation into systemic disease.²

 The extent of the lymphoma should be staged to exclude the possibility of systemic disease. This assessment includes a complete physical examination; laboratory investigation, including complete blood cell count with differential and blood chemistries; and radiography. A positron emission tomography-CT scan of the neck, chest, abdomen, and pelvis, or a whole-body integrated positron emission tomography-CT are sufficient for the radiographic examination.³ 

The initial choice of treatment for solitary or localized PC-ALCL is localized radiation therapy or low-dose methotrexate. Targeted therapy such as brentuximab has been shown to be effective for those with multifocal systemic involvement or refractory disease.² Cure rates from radiation therapy alone approach 95%.³ It is important to highlight radiation therapy as the initial management plan to increase awareness and to avoid inappropriate treatment of PC-ALCL with traditional chemotherapy. 

Large lesions of LyP may appear similar to PC-ALCL on histopathology, making the two entities difficult to distinguish. However, in contrast to PC-ALCL, LyP classically has a different clinical course characterized by waxing and waning crops of lesions that typically are smaller (<1 cm) than those of PC-ALCL.² Large cell transformation of mycosis fungoides is another entity to consider, but these patients usually have a known history of mycosis fungoides.⁴ 

Keratoacanthomas, considered to be a variant of a well-differentiated squamous cell carcinoma, present as rapidly enlarging crateriform nodules with a keratotic core. They usually are found on the head and neck or sun-exposed areas of the extremities and may regress spontaneously.⁵ Histology will show atypical, highly differentiated squamous epithelia. Merkel cell carcinoma also has a predilection for the head and neck in older patients and may present as a rapidly growing nodule. However, histology will show an aggressive tumor with small round blue cells, and immunohistochemistry will show the characteristic paranuclear dot staining for CK20 along with staining for various neuroendocrine markers. Similarly, atypical fibroxanthoma is a low-grade sarcoma that also presents on the head and neck of elderly sun-damaged patients.⁵ Histology will show dermal proliferation of spindle cells that often extend up against the epidermis along with pleomorphism and atypical mitoses. Basal cell carcinoma is a common tumor that can present on the head and neck in sun-damaged patients. Nodular basal cell carcinomas can enlarge and ulcerate, but growth is seen over years rather than weeks.⁵ Histology characteristically will show tumor islands composed of basaloid cells with peripheral palisading and clefting between the tumor islands and the stroma.  

The Diagnosis: Primary Cutaneous Anaplastic Large Cell Lymphoma  

Microscopic analysis showed a dense proliferation of mononuclear cells filling and expanding the dermis with focal epidermotropism (Figure 1). Immunohistochemistry demonstrated strong and diffuse staining for CD3, CD4, and CD30 (Figure 2) and lack of staining for anaplastic lymphoma kinase (ALK). Workup to exclude systemic disease was initiated and included unremarkable computed tomography (CT) of the neck, chest, abdomen, and pelvis along with no abnormal cells on bone marrow biopsy. Complete blood cell count, basic metabolic panel, and lactate dehydrogenase were within reference range. Given the lack of evidence for systemic involvement, a diagnosis of primary cutaneous anaplastic large cell lymphoma (PC-ALCL) was made. The treatment plan for our patient with a solitary lesion was localized radiation therapy. 

Primary cutaneous CD30⁺ lymphoproliferative disorders encompass a spectrum of conditions, with premalignant lymphomatoid papulosis (LyP) at one extreme and the malignant PC-ALCL on the other.¹ The diagnosis of PC-ALCL is made by clinicopathologic correlation, and lesions typically present abruptly as solitary or grouped nodules with a tendency to ulcerate over time. Spontaneous regression has been reported, but relapse in the skin is frequent.² 

A representative, typically excisional, biopsy should be performed if the clinician suspects PC-ALCL. Histologic criteria include a dense dermal infiltrate of large pleomorphic cells and the expression of CD30 in at least 75% of tumor cells.³ Primary cutaneous anaplastic large cell lymphoma typically lacks the ALK gene translocation with the nucleophosmin gene, NPM, that is common in systemic disease; however, a small subset of PC-ALCL may be ALK positive and indicate a higher chance of transformation into systemic disease.²

 The extent of the lymphoma should be staged to exclude the possibility of systemic disease. This assessment includes a complete physical examination; laboratory investigation, including complete blood cell count with differential and blood chemistries; and radiography. A positron emission tomography-CT scan of the neck, chest, abdomen, and pelvis, or a whole-body integrated positron emission tomography-CT are sufficient for the radiographic examination.³ 

The initial choice of treatment for solitary or localized PC-ALCL is localized radiation therapy or low-dose methotrexate. Targeted therapy such as brentuximab has been shown to be effective for those with multifocal systemic involvement or refractory disease.² Cure rates from radiation therapy alone approach 95%.³ It is important to highlight radiation therapy as the initial management plan to increase awareness and to avoid inappropriate treatment of PC-ALCL with traditional chemotherapy. 

Large lesions of LyP may appear similar to PC-ALCL on histopathology, making the two entities difficult to distinguish. However, in contrast to PC-ALCL, LyP classically has a different clinical course characterized by waxing and waning crops of lesions that typically are smaller (<1 cm) than those of PC-ALCL.² Large cell transformation of mycosis fungoides is another entity to consider, but these patients usually have a known history of mycosis fungoides.⁴ 

Keratoacanthomas, considered to be a variant of a well-differentiated squamous cell carcinoma, present as rapidly enlarging crateriform nodules with a keratotic core. They usually are found on the head and neck or sun-exposed areas of the extremities and may regress spontaneously.⁵ Histology will show atypical, highly differentiated squamous epithelia. Merkel cell carcinoma also has a predilection for the head and neck in older patients and may present as a rapidly growing nodule. However, histology will show an aggressive tumor with small round blue cells, and immunohistochemistry will show the characteristic paranuclear dot staining for CK20 along with staining for various neuroendocrine markers. Similarly, atypical fibroxanthoma is a low-grade sarcoma that also presents on the head and neck of elderly sun-damaged patients.⁵ Histology will show dermal proliferation of spindle cells that often extend up against the epidermis along with pleomorphism and atypical mitoses. Basal cell carcinoma is a common tumor that can present on the head and neck in sun-damaged patients. Nodular basal cell carcinomas can enlarge and ulcerate, but growth is seen over years rather than weeks.⁵ Histology characteristically will show tumor islands composed of basaloid cells with peripheral palisading and clefting between the tumor islands and the stroma.  

According to National Institutes of Health estimates, more than 90,000 new cases of melanoma were diagnosed in 2018.¹ Overall 5-year survival for patients with melanoma exceeds 90%, but individual survival estimates are highly dependent on stage at diagnosis, and survival decreases markedly with metastasis. Therefore, early and accurate diagnosis is critical.

Diagnosis of melanocytic neoplasms usually is performed by dermatopathologists through microscopic examination of stained tissue biopsy sections, a technically simple and effective method that enables a definitive diagnosis of benign nevus or malignant melanoma to be made in most cases. However, approximately 15% of all biopsied melanocytic lesions will exhibit some degree of histopathologic ambiguity,^2-4 meaning that some of their microscopic features will be characteristic of a benign nevus while others will suggest the possibility of malignant melanoma. Diagnostic interpretations often vary in these cases, even among experts, and a definitive diagnosis of benign or malignant may be difficult to achieve by microscopy alone.^2-4 Because of the marked reduction in survival once a melanoma has metastasized, these diagnostically ambiguous lesions often are treated as possible malignant melanomas with complete surgical excision (or re-excision). However, some experts suggest that many histopathologically ambiguous melanocytic neoplasms are, in fact, benign,⁵ a notion supported by epidemiologic evidence.^6,7 Therefore, excision of many ambiguous melanocytic neoplasms might be avoided if definitive diagnosis could be achieved.

A gene expression signature was developed and validated for use as an adjunct to traditional methods of differentiating malignant melanocytic neoplasms from their benign counterparts.^8-11 This test quantifies the RNA transcripts produced by 14 genes known to be overexpressed in malignant melanomas by comparison to benign nevi. These values are then combined algorithmically with measurements of 9 reference genes to produce an objective numerical score that is classified as benign, malignant, or indeterminate. When used by board-certified dermatopathologists and dermatologists confronting ambiguous melanocytic lesions, the test produces substantial increases in definitive diagnoses and prompts changes in treatment recommendations.^12,13 However, the long-term consequences of foregoing surgical excision of melanocytic neoplasms that are diagnostically ambiguous but classified as benign by this test have not yet been formally assessed. In the current study, prospectively tested patients whose ambiguous melanocytic neoplasms were classified as benign by the gene expression signature were followed for up to 4.5 years to evaluate the long-term safety of treatment decisions aligned with benign test results.

Methods

Study Population
As part of a prior study,¹² US-based dermatopathologists submitted tissue sections from biopsied melanocytic neoplasms determined to be diagnostically ambiguous by histopathology for analysis with the gene expression signature (Myriad Genetics, Inc). Diagnostically ambiguous lesions were those lesions that were described as ambiguous, uncertain, equivocal, indeterminate, or other synonymous terms by the submitting dermatopathologist and therefore lacked a confident diagnosis of benign or malignant prior to testing. Patients initially were tested between May 2014 and August 2014, with samples submitted through a prospective clinical experience study designed to assess the impact of the test on diagnosis and treatment decisions. This study was performed under an institutional review board waiver of consent (Quorum #33403/1).

Patients were eligible for inclusion in the current study if their biopsy specimens (1) had an uncertain preliminary diagnosis according to the submitting dermatopathologist (pretest diagnosis of indeterminate); (2) received a negative (benign) score from the gene expression test; (3) were treated as benign by the dermatologist(s) involved in follow-up care; and (4) were submitted by a single site (St. Joseph Medical Center, Houston, Texas). Although a single dermatopathology site was used for this study, multiple dermatologists were involved in the final treatment of these patients. Patients with benign scores who received additional intervention were excluded, as they may have a lower rate of adverse events (ie, metastasis) than those who did not receive intervention and would therefore skew the analysis population. A total of 25 patients from the prior study met these inclusion criteria. The previously collected¹² pretest and posttest de-identified data were compiled from the commercial laboratory databases, and the patients were followed from the time of testing via medical record review performed by the dermatology providers at participating sites. Clinical follow-up data were collected using study-specific case report forms (CRFs) that captured the following: (1) the dates and results of clinical follow-up visits; (2) the type(s) of treatment and interventions (if any) performed at those visits; (3) the specific indication for any intervention performed; (4) any evidence of persistent, locally recurrent, and/or distant melanocytic neoplasia (whether definitively attributable to the tested lesion or not); and (5) death from any cause. The CRF assigned interventions to 1 of 5 categories: excision, excision with sentinel lymph node biopsy, referral to dermatologic or other surgeon, examination only (without surgical intervention), and other. Selection of other required a free-text description of the treatment and indications. Pertinent information not otherwise captured by the CRF also was recordable as free text.

Gene Expression Testing
Gene expression testing was carried out at the time of specimen submission in the prior study¹² as described previously.¹⁴ Briefly, formalin-fixed, paraffin-embedded, unstained tissue sections and/or tissue blocks were submitted for testing along with a single hematoxylin and eosin–stained slide used to identify and designate the representative portion(s) of the lesion to be tested. These areas were macrodissected from unstained tissue sections and pooled for RNA extraction. Expression of 14 biomarker genes and 9 reference genes was measured via quantitative reverse transcription–polymerase chain reaction, performed in triplicate for each individual gene. The assay score was generated through application of a weighted algorithm to the expression values generated through quantitative reverse transcription–polymerase chain reaction. Scores were plotted on a scale ranging from −16.7 to 11.1, with scores from 0.0 to 11.1 classified as malignant, scores from −16.7 to −2.1 as benign, and scores from −2.1 to −0.1 as indeterminate.

Statistical Analysis
Demographic and other baseline characteristics of the patient population were summarized. Follow-up time was calculated as the interval between the date a patient’s gene expression test result was first issued to the provider and the date of the patient’s last recorded visit during the study period. All patient dermatology office visits within the designated follow-up period were documented, with a nonstandard number of visits and follow-up time across all study patients. Statistical analyses were conducted using SAS software (SAS Institute Inc), R software version 3.5.0 (R Foundation for Statistical Computing), and IBM SPSS Statistics software (IBM SPSS Statistics for Windows, Version 25).

 

Results

Patient Sample
A total of 25 ambiguous melanocytic neoplasms from 25 patients met the study inclusion criteria of a benign gene expression result with subsequent treatment as a benign neoplasm during follow-up. The patient sample statistics are summarized in Table 1. Most patients were younger than 65 years, with an average age at the time of biopsy of 48.4 years. All 25 neoplasms produced negative (benign) gene expression signature scores, all were diagnosed as benign nevi posttest by the submitting dermatopathologist, and all patients were initially treated in accordance with the benign diagnosis by the dermatologist(s) involved in clinical follow-up care. Prior to testing with the gene expression signature, most of these histopathologically indeterminate lesions received differential diagnoses, the most common of which were dysplastic nevus (84%), melanoma arising from a nevus (72%), and superficial spreading melanoma (64%; eTable). After testing with the gene expression signature and receiving a benign score, most lesions received a single differential diagnosis of dysplastic nevus (88%).

Follow-up and Survival
Clinical follow-up time ranged from 0.6 to 53.3 months, with a mean duration (SD) of 38.5 (16.6) months, and patients attended an average of 4 postbiopsy dermatology appointments (mean [SD], 4.6 [3.6]). According to the participating dermatology care providers, none of the 25 patients developed any indication during follow-up that the diagnosis of benign nevus was inaccurate. No patient had evidence of locally recurrent or metastatic melanoma, and none died during the study period.

Treatment/Interventions
The treatment recorded in the CRF was examination only for 21 of 25 patients, excision for 3, and other for 1 (Table 2). Because the explanation for the selection of other in this case described an excision performed at the same anatomic location as the biopsy, this treatment also was considered an excision for purposes of the study analyses. The 3 excisions all occurred at the first postbiopsy dermatology encounter. Across all follow-up visits, no additional surgical interventions occurred (Table 2).

The first excision (case 1) involved a 67-year-old woman with a lesion on the mid pubic region described clinically as an atypical nevus that generated a pretest histopathologic differential diagnosis including dysplastic nevus, superficial spreading melanoma, and melanoma arising within a nevus (Table 3; Figure, A and B). The gene expression test result was benign (score, −5.4), and the final pathology report diagnosis was nevus with junctional dysplasia, moderate. Surgical excision was performed at the patient’s first return visit, 505 days after initial diagnosis, with moderately dysplastic nevus as the recorded indication for removal. No repigmentation or other evidence of local recurrence or progression was detected, and the treating dermatologist indicated no suspicion that the original diagnosis of benign nevus was incorrect during the 23-month follow-up period.

The second excision (case 2) involved a 27-year-old woman with a pigmented neoplasm on the mid upper back (Figure, C and D) biopsied to rule out dysplastic nevus that resulted in a pretest histopathologic differential diagnosis of dysplastic nevus vs superficial spreading melanoma or melanoma arising within a nevus. The gene expression test result classified the lesion as benign (score, −2.9), and the final pathology diagnosis was nevus, compound, with moderate dysplasia. Despite the benign diagnosis, residual neoplasm (or pigmentation) at the biopsy site prompted the patient to request excision at her first postbiopsy visit, 22 days after testing (Table 3). The CRF completed by the dermatologist reported no indication that the benign diagnosis was inaccurate, but the patient was subsequently lost to follow-up.

The third excision (case 3) involved a 32-year-old woman with a pigmented lesion on the abdomen (Table 3; Figure, E and F). The clinical description was irregular-appearing black papule, nevus with atypia, and the histopathologic differential diagnosis again included dysplastic nevus, superficial spreading melanoma, and melanoma arising within a preexisting nevus. The gene expression signature result was benign (score, −7.2), and the final diagnosis issued within the accompanying pathology report was nevus with moderate junctional dysplasia. Despite the benign diagnosis, excision was performed 89 days after test result availability, with apparent residual pigmentation as the specified indication. As with the other 2 cases, the treating dermatologist confirmed that neither clinical features nor follow-up events suggested malignancy.

Comment

This study followed a cohort of 25 patients with histopathologically ambiguous melanocytic neoplasms that were classified as benign by a diagnostic gene expression test with the intent of determining the outcomes of patients whose treatment aligned with their benign test result. All patients initially were managed according to their test result. During an average posttest clinical follow-up time of more than 3 years (38.5 months), the 25 biopsied lesions, most of which received a differential diagnosis of dysplastic nevus, were regarded as benign nevi by their dermatologists, and the vast majority (88%) received no further surgical intervention. Three patients underwent subsequent excision of the biopsied lesion, with patient or physician preference as the indication in each instance. None of the 25 patients developed evidence of local recurrence, metastasis, or other findings that prompted doubt of the benign diagnosis. The absence of adverse events during clinical follow-up, particularly given that most lesions were not subjected to further intervention, supports use of the gene expression test as a safe and effective adjunct to the diagnosis and treatment of ambiguous melanocytic neoplasms by dermatologists and dermatopathologists.

 

Ambiguous melanocytic neoplasms evaluated without the aid of molecular adjuncts often result in equivocal or less-than-definitive diagnoses, and further surgical intervention is commonly undertaken to mitigate against the possibility of a missed melanoma.¹³ In this study, treatment that was aligned with the benign test result allowed most patients to avoid further surgical intervention, which suggests that adjunctive use of the gene signature can contribute to reductions in the physical and economic burdens imposed by unnecessary surgical interventions.^15,16 Moreover, any means of increasing accurate and definitive diagnoses may produce an immediate impact on health outcomes by reducing the anxiety that uncertainty often provokes in patients and health care providers alike.

Study Limitations
This study must be interpreted within the context of its limitations. Obtaining meaningful patient outcome data is a common challenge in health care research due to the requisite length of follow-up and sometimes the lack of definitive evidence of adverse events. This is particularly difficult for melanocytic neoplasms because of an apparent inclination for patients with benign diagnoses to abandon follow-up and an increasing tendency for even minimal diagnostic uncertainty to prompt complete excision. Additionally, the only definitive clinical outcome for melanocytic neoplasms is distant metastasis, which (fortunately for patients) is relatively rare. Not surprisingly, studies documenting clinical outcomes of patients with ambiguous melanocytic neoplasms tested prospectively with diagnostic adjuncts are scarce, and this study’s sample size and clinical follow-up compare favorably with the few that exist.^17,18 Although most melanomas declare themselves through recurrence or metastasis within several years of initial biopsy,^1,19 some are clinically dormant for as long as 10 years after initial detection.^20,21 This may be particularly true for the small or early-stage lesions that now comprise the majority of biopsied neoplasms, and such events would go undetected by this study and many others. It also must be recognized that uneventful follow-up, regardless of duration, cannot prove that a biopsied melanocytic neoplasm was benign. Although only 5 patients had a follow-up time of less than 2 years (the time frame in which most recurrence or metastasis will occur), it cannot be definitively proven that a minimum of 2 years recurrence- or metastasis-free survival indicates a benign lesion. Many early-stage malignant melanomas are eradicated by complete excision or even by the initial biopsy if margins are uninvolved.

Because these limitations are intrinsic to melanocytic neoplasms and current management strategies, they pertain to all investigations seeking insights into biological potential through clinical outcomes. Similarly, all current diagnostic tools and procedures have the potential for sampling error, including histopathology. The rarity of adverse outcomes (recurrence and metastasis) in patients with benign test results within this cohort indicates that false-negative results are uncommon, which is further evidenced by a similar rarity of adverse events in prior studies of the gene expression signature.^8-10,22 A particular strength of this study is that most of the ambiguous melanocytic neoplasms followed did not undergo excision after the initial biopsy, an increasingly uncommon situation that may increase their likelihood to be informative.

It must be emphasized that the gene expression test, similar to other diagnostic adjuncts, is neither a replacement for histopathologic interpretation nor a substitute for judgment. As with all tests, it can produce false-positive and false-negative results. Therefore, it should always be interpreted within the constellation of the many other data points that must be considered when making a distinction between benign nevus and malignant melanoma, including but not limited to patient age, family and personal history of melanoma, anatomic location, clinical features, and histopathologic findings. As is the case for many diseases, careful consideration of all relevant input is necessary to minimize the risk of misdiagnosis that might occur should any single data point prove inaccurate, including the results of adjunctive molecular tests.

Conclusion

Ancillary methods are emerging as useful tools for the diagnostic evaluation of melanocytic neoplasms that cannot be assigned definitive diagnoses using traditional techniques alone. This study suggests that patients with ambiguous melanocytic neoplasms may benefit from diagnoses and treatment decisions aligned with the results of a gene expression test, and that for those with a benign result, simple observation may be a safe alternative to surgical excision. This expands upon prior observations of the test’s influence on diagnoses and treatment decisions and supports its role as part of dermatopathologists’ and dermatologists’ decision-making process for histopathologically ambiguous melanocytic lesions.

According to National Institutes of Health estimates, more than 90,000 new cases of melanoma were diagnosed in 2018.¹ Overall 5-year survival for patients with melanoma exceeds 90%, but individual survival estimates are highly dependent on stage at diagnosis, and survival decreases markedly with metastasis. Therefore, early and accurate diagnosis is critical.

Diagnosis of melanocytic neoplasms usually is performed by dermatopathologists through microscopic examination of stained tissue biopsy sections, a technically simple and effective method that enables a definitive diagnosis of benign nevus or malignant melanoma to be made in most cases. However, approximately 15% of all biopsied melanocytic lesions will exhibit some degree of histopathologic ambiguity,^2-4 meaning that some of their microscopic features will be characteristic of a benign nevus while others will suggest the possibility of malignant melanoma. Diagnostic interpretations often vary in these cases, even among experts, and a definitive diagnosis of benign or malignant may be difficult to achieve by microscopy alone.^2-4 Because of the marked reduction in survival once a melanoma has metastasized, these diagnostically ambiguous lesions often are treated as possible malignant melanomas with complete surgical excision (or re-excision). However, some experts suggest that many histopathologically ambiguous melanocytic neoplasms are, in fact, benign,⁵ a notion supported by epidemiologic evidence.^6,7 Therefore, excision of many ambiguous melanocytic neoplasms might be avoided if definitive diagnosis could be achieved.

A gene expression signature was developed and validated for use as an adjunct to traditional methods of differentiating malignant melanocytic neoplasms from their benign counterparts.^8-11 This test quantifies the RNA transcripts produced by 14 genes known to be overexpressed in malignant melanomas by comparison to benign nevi. These values are then combined algorithmically with measurements of 9 reference genes to produce an objective numerical score that is classified as benign, malignant, or indeterminate. When used by board-certified dermatopathologists and dermatologists confronting ambiguous melanocytic lesions, the test produces substantial increases in definitive diagnoses and prompts changes in treatment recommendations.^12,13 However, the long-term consequences of foregoing surgical excision of melanocytic neoplasms that are diagnostically ambiguous but classified as benign by this test have not yet been formally assessed. In the current study, prospectively tested patients whose ambiguous melanocytic neoplasms were classified as benign by the gene expression signature were followed for up to 4.5 years to evaluate the long-term safety of treatment decisions aligned with benign test results.

Methods

Study Population
As part of a prior study,¹² US-based dermatopathologists submitted tissue sections from biopsied melanocytic neoplasms determined to be diagnostically ambiguous by histopathology for analysis with the gene expression signature (Myriad Genetics, Inc). Diagnostically ambiguous lesions were those lesions that were described as ambiguous, uncertain, equivocal, indeterminate, or other synonymous terms by the submitting dermatopathologist and therefore lacked a confident diagnosis of benign or malignant prior to testing. Patients initially were tested between May 2014 and August 2014, with samples submitted through a prospective clinical experience study designed to assess the impact of the test on diagnosis and treatment decisions. This study was performed under an institutional review board waiver of consent (Quorum #33403/1).

Patients were eligible for inclusion in the current study if their biopsy specimens (1) had an uncertain preliminary diagnosis according to the submitting dermatopathologist (pretest diagnosis of indeterminate); (2) received a negative (benign) score from the gene expression test; (3) were treated as benign by the dermatologist(s) involved in follow-up care; and (4) were submitted by a single site (St. Joseph Medical Center, Houston, Texas). Although a single dermatopathology site was used for this study, multiple dermatologists were involved in the final treatment of these patients. Patients with benign scores who received additional intervention were excluded, as they may have a lower rate of adverse events (ie, metastasis) than those who did not receive intervention and would therefore skew the analysis population. A total of 25 patients from the prior study met these inclusion criteria. The previously collected¹² pretest and posttest de-identified data were compiled from the commercial laboratory databases, and the patients were followed from the time of testing via medical record review performed by the dermatology providers at participating sites. Clinical follow-up data were collected using study-specific case report forms (CRFs) that captured the following: (1) the dates and results of clinical follow-up visits; (2) the type(s) of treatment and interventions (if any) performed at those visits; (3) the specific indication for any intervention performed; (4) any evidence of persistent, locally recurrent, and/or distant melanocytic neoplasia (whether definitively attributable to the tested lesion or not); and (5) death from any cause. The CRF assigned interventions to 1 of 5 categories: excision, excision with sentinel lymph node biopsy, referral to dermatologic or other surgeon, examination only (without surgical intervention), and other. Selection of other required a free-text description of the treatment and indications. Pertinent information not otherwise captured by the CRF also was recordable as free text.

Gene Expression Testing
Gene expression testing was carried out at the time of specimen submission in the prior study¹² as described previously.¹⁴ Briefly, formalin-fixed, paraffin-embedded, unstained tissue sections and/or tissue blocks were submitted for testing along with a single hematoxylin and eosin–stained slide used to identify and designate the representative portion(s) of the lesion to be tested. These areas were macrodissected from unstained tissue sections and pooled for RNA extraction. Expression of 14 biomarker genes and 9 reference genes was measured via quantitative reverse transcription–polymerase chain reaction, performed in triplicate for each individual gene. The assay score was generated through application of a weighted algorithm to the expression values generated through quantitative reverse transcription–polymerase chain reaction. Scores were plotted on a scale ranging from −16.7 to 11.1, with scores from 0.0 to 11.1 classified as malignant, scores from −16.7 to −2.1 as benign, and scores from −2.1 to −0.1 as indeterminate.

Statistical Analysis
Demographic and other baseline characteristics of the patient population were summarized. Follow-up time was calculated as the interval between the date a patient’s gene expression test result was first issued to the provider and the date of the patient’s last recorded visit during the study period. All patient dermatology office visits within the designated follow-up period were documented, with a nonstandard number of visits and follow-up time across all study patients. Statistical analyses were conducted using SAS software (SAS Institute Inc), R software version 3.5.0 (R Foundation for Statistical Computing), and IBM SPSS Statistics software (IBM SPSS Statistics for Windows, Version 25).

 

Results

Patient Sample
A total of 25 ambiguous melanocytic neoplasms from 25 patients met the study inclusion criteria of a benign gene expression result with subsequent treatment as a benign neoplasm during follow-up. The patient sample statistics are summarized in Table 1. Most patients were younger than 65 years, with an average age at the time of biopsy of 48.4 years. All 25 neoplasms produced negative (benign) gene expression signature scores, all were diagnosed as benign nevi posttest by the submitting dermatopathologist, and all patients were initially treated in accordance with the benign diagnosis by the dermatologist(s) involved in clinical follow-up care. Prior to testing with the gene expression signature, most of these histopathologically indeterminate lesions received differential diagnoses, the most common of which were dysplastic nevus (84%), melanoma arising from a nevus (72%), and superficial spreading melanoma (64%; eTable). After testing with the gene expression signature and receiving a benign score, most lesions received a single differential diagnosis of dysplastic nevus (88%).

Follow-up and Survival
Clinical follow-up time ranged from 0.6 to 53.3 months, with a mean duration (SD) of 38.5 (16.6) months, and patients attended an average of 4 postbiopsy dermatology appointments (mean [SD], 4.6 [3.6]). According to the participating dermatology care providers, none of the 25 patients developed any indication during follow-up that the diagnosis of benign nevus was inaccurate. No patient had evidence of locally recurrent or metastatic melanoma, and none died during the study period.

Treatment/Interventions
The treatment recorded in the CRF was examination only for 21 of 25 patients, excision for 3, and other for 1 (Table 2). Because the explanation for the selection of other in this case described an excision performed at the same anatomic location as the biopsy, this treatment also was considered an excision for purposes of the study analyses. The 3 excisions all occurred at the first postbiopsy dermatology encounter. Across all follow-up visits, no additional surgical interventions occurred (Table 2).

The first excision (case 1) involved a 67-year-old woman with a lesion on the mid pubic region described clinically as an atypical nevus that generated a pretest histopathologic differential diagnosis including dysplastic nevus, superficial spreading melanoma, and melanoma arising within a nevus (Table 3; Figure, A and B). The gene expression test result was benign (score, −5.4), and the final pathology report diagnosis was nevus with junctional dysplasia, moderate. Surgical excision was performed at the patient’s first return visit, 505 days after initial diagnosis, with moderately dysplastic nevus as the recorded indication for removal. No repigmentation or other evidence of local recurrence or progression was detected, and the treating dermatologist indicated no suspicion that the original diagnosis of benign nevus was incorrect during the 23-month follow-up period.

The second excision (case 2) involved a 27-year-old woman with a pigmented neoplasm on the mid upper back (Figure, C and D) biopsied to rule out dysplastic nevus that resulted in a pretest histopathologic differential diagnosis of dysplastic nevus vs superficial spreading melanoma or melanoma arising within a nevus. The gene expression test result classified the lesion as benign (score, −2.9), and the final pathology diagnosis was nevus, compound, with moderate dysplasia. Despite the benign diagnosis, residual neoplasm (or pigmentation) at the biopsy site prompted the patient to request excision at her first postbiopsy visit, 22 days after testing (Table 3). The CRF completed by the dermatologist reported no indication that the benign diagnosis was inaccurate, but the patient was subsequently lost to follow-up.

The third excision (case 3) involved a 32-year-old woman with a pigmented lesion on the abdomen (Table 3; Figure, E and F). The clinical description was irregular-appearing black papule, nevus with atypia, and the histopathologic differential diagnosis again included dysplastic nevus, superficial spreading melanoma, and melanoma arising within a preexisting nevus. The gene expression signature result was benign (score, −7.2), and the final diagnosis issued within the accompanying pathology report was nevus with moderate junctional dysplasia. Despite the benign diagnosis, excision was performed 89 days after test result availability, with apparent residual pigmentation as the specified indication. As with the other 2 cases, the treating dermatologist confirmed that neither clinical features nor follow-up events suggested malignancy.

Comment

This study followed a cohort of 25 patients with histopathologically ambiguous melanocytic neoplasms that were classified as benign by a diagnostic gene expression test with the intent of determining the outcomes of patients whose treatment aligned with their benign test result. All patients initially were managed according to their test result. During an average posttest clinical follow-up time of more than 3 years (38.5 months), the 25 biopsied lesions, most of which received a differential diagnosis of dysplastic nevus, were regarded as benign nevi by their dermatologists, and the vast majority (88%) received no further surgical intervention. Three patients underwent subsequent excision of the biopsied lesion, with patient or physician preference as the indication in each instance. None of the 25 patients developed evidence of local recurrence, metastasis, or other findings that prompted doubt of the benign diagnosis. The absence of adverse events during clinical follow-up, particularly given that most lesions were not subjected to further intervention, supports use of the gene expression test as a safe and effective adjunct to the diagnosis and treatment of ambiguous melanocytic neoplasms by dermatologists and dermatopathologists.

 

Ambiguous melanocytic neoplasms evaluated without the aid of molecular adjuncts often result in equivocal or less-than-definitive diagnoses, and further surgical intervention is commonly undertaken to mitigate against the possibility of a missed melanoma.¹³ In this study, treatment that was aligned with the benign test result allowed most patients to avoid further surgical intervention, which suggests that adjunctive use of the gene signature can contribute to reductions in the physical and economic burdens imposed by unnecessary surgical interventions.^15,16 Moreover, any means of increasing accurate and definitive diagnoses may produce an immediate impact on health outcomes by reducing the anxiety that uncertainty often provokes in patients and health care providers alike.

Study Limitations
This study must be interpreted within the context of its limitations. Obtaining meaningful patient outcome data is a common challenge in health care research due to the requisite length of follow-up and sometimes the lack of definitive evidence of adverse events. This is particularly difficult for melanocytic neoplasms because of an apparent inclination for patients with benign diagnoses to abandon follow-up and an increasing tendency for even minimal diagnostic uncertainty to prompt complete excision. Additionally, the only definitive clinical outcome for melanocytic neoplasms is distant metastasis, which (fortunately for patients) is relatively rare. Not surprisingly, studies documenting clinical outcomes of patients with ambiguous melanocytic neoplasms tested prospectively with diagnostic adjuncts are scarce, and this study’s sample size and clinical follow-up compare favorably with the few that exist.^17,18 Although most melanomas declare themselves through recurrence or metastasis within several years of initial biopsy,^1,19 some are clinically dormant for as long as 10 years after initial detection.^20,21 This may be particularly true for the small or early-stage lesions that now comprise the majority of biopsied neoplasms, and such events would go undetected by this study and many others. It also must be recognized that uneventful follow-up, regardless of duration, cannot prove that a biopsied melanocytic neoplasm was benign. Although only 5 patients had a follow-up time of less than 2 years (the time frame in which most recurrence or metastasis will occur), it cannot be definitively proven that a minimum of 2 years recurrence- or metastasis-free survival indicates a benign lesion. Many early-stage malignant melanomas are eradicated by complete excision or even by the initial biopsy if margins are uninvolved.

Because these limitations are intrinsic to melanocytic neoplasms and current management strategies, they pertain to all investigations seeking insights into biological potential through clinical outcomes. Similarly, all current diagnostic tools and procedures have the potential for sampling error, including histopathology. The rarity of adverse outcomes (recurrence and metastasis) in patients with benign test results within this cohort indicates that false-negative results are uncommon, which is further evidenced by a similar rarity of adverse events in prior studies of the gene expression signature.^8-10,22 A particular strength of this study is that most of the ambiguous melanocytic neoplasms followed did not undergo excision after the initial biopsy, an increasingly uncommon situation that may increase their likelihood to be informative.

It must be emphasized that the gene expression test, similar to other diagnostic adjuncts, is neither a replacement for histopathologic interpretation nor a substitute for judgment. As with all tests, it can produce false-positive and false-negative results. Therefore, it should always be interpreted within the constellation of the many other data points that must be considered when making a distinction between benign nevus and malignant melanoma, including but not limited to patient age, family and personal history of melanoma, anatomic location, clinical features, and histopathologic findings. As is the case for many diseases, careful consideration of all relevant input is necessary to minimize the risk of misdiagnosis that might occur should any single data point prove inaccurate, including the results of adjunctive molecular tests.

Conclusion

Ancillary methods are emerging as useful tools for the diagnostic evaluation of melanocytic neoplasms that cannot be assigned definitive diagnoses using traditional techniques alone. This study suggests that patients with ambiguous melanocytic neoplasms may benefit from diagnoses and treatment decisions aligned with the results of a gene expression test, and that for those with a benign result, simple observation may be a safe alternative to surgical excision. This expands upon prior observations of the test’s influence on diagnoses and treatment decisions and supports its role as part of dermatopathologists’ and dermatologists’ decision-making process for histopathologically ambiguous melanocytic lesions.

According to National Institutes of Health estimates, more than 90,000 new cases of melanoma were diagnosed in 2018.¹ Overall 5-year survival for patients with melanoma exceeds 90%, but individual survival estimates are highly dependent on stage at diagnosis, and survival decreases markedly with metastasis. Therefore, early and accurate diagnosis is critical.

Diagnosis of melanocytic neoplasms usually is performed by dermatopathologists through microscopic examination of stained tissue biopsy sections, a technically simple and effective method that enables a definitive diagnosis of benign nevus or malignant melanoma to be made in most cases. However, approximately 15% of all biopsied melanocytic lesions will exhibit some degree of histopathologic ambiguity,^2-4 meaning that some of their microscopic features will be characteristic of a benign nevus while others will suggest the possibility of malignant melanoma. Diagnostic interpretations often vary in these cases, even among experts, and a definitive diagnosis of benign or malignant may be difficult to achieve by microscopy alone.^2-4 Because of the marked reduction in survival once a melanoma has metastasized, these diagnostically ambiguous lesions often are treated as possible malignant melanomas with complete surgical excision (or re-excision). However, some experts suggest that many histopathologically ambiguous melanocytic neoplasms are, in fact, benign,⁵ a notion supported by epidemiologic evidence.^6,7 Therefore, excision of many ambiguous melanocytic neoplasms might be avoided if definitive diagnosis could be achieved.

A gene expression signature was developed and validated for use as an adjunct to traditional methods of differentiating malignant melanocytic neoplasms from their benign counterparts.^8-11 This test quantifies the RNA transcripts produced by 14 genes known to be overexpressed in malignant melanomas by comparison to benign nevi. These values are then combined algorithmically with measurements of 9 reference genes to produce an objective numerical score that is classified as benign, malignant, or indeterminate. When used by board-certified dermatopathologists and dermatologists confronting ambiguous melanocytic lesions, the test produces substantial increases in definitive diagnoses and prompts changes in treatment recommendations.^12,13 However, the long-term consequences of foregoing surgical excision of melanocytic neoplasms that are diagnostically ambiguous but classified as benign by this test have not yet been formally assessed. In the current study, prospectively tested patients whose ambiguous melanocytic neoplasms were classified as benign by the gene expression signature were followed for up to 4.5 years to evaluate the long-term safety of treatment decisions aligned with benign test results.

Methods

Study Population
As part of a prior study,¹² US-based dermatopathologists submitted tissue sections from biopsied melanocytic neoplasms determined to be diagnostically ambiguous by histopathology for analysis with the gene expression signature (Myriad Genetics, Inc). Diagnostically ambiguous lesions were those lesions that were described as ambiguous, uncertain, equivocal, indeterminate, or other synonymous terms by the submitting dermatopathologist and therefore lacked a confident diagnosis of benign or malignant prior to testing. Patients initially were tested between May 2014 and August 2014, with samples submitted through a prospective clinical experience study designed to assess the impact of the test on diagnosis and treatment decisions. This study was performed under an institutional review board waiver of consent (Quorum #33403/1).

Patients were eligible for inclusion in the current study if their biopsy specimens (1) had an uncertain preliminary diagnosis according to the submitting dermatopathologist (pretest diagnosis of indeterminate); (2) received a negative (benign) score from the gene expression test; (3) were treated as benign by the dermatologist(s) involved in follow-up care; and (4) were submitted by a single site (St. Joseph Medical Center, Houston, Texas). Although a single dermatopathology site was used for this study, multiple dermatologists were involved in the final treatment of these patients. Patients with benign scores who received additional intervention were excluded, as they may have a lower rate of adverse events (ie, metastasis) than those who did not receive intervention and would therefore skew the analysis population. A total of 25 patients from the prior study met these inclusion criteria. The previously collected¹² pretest and posttest de-identified data were compiled from the commercial laboratory databases, and the patients were followed from the time of testing via medical record review performed by the dermatology providers at participating sites. Clinical follow-up data were collected using study-specific case report forms (CRFs) that captured the following: (1) the dates and results of clinical follow-up visits; (2) the type(s) of treatment and interventions (if any) performed at those visits; (3) the specific indication for any intervention performed; (4) any evidence of persistent, locally recurrent, and/or distant melanocytic neoplasia (whether definitively attributable to the tested lesion or not); and (5) death from any cause. The CRF assigned interventions to 1 of 5 categories: excision, excision with sentinel lymph node biopsy, referral to dermatologic or other surgeon, examination only (without surgical intervention), and other. Selection of other required a free-text description of the treatment and indications. Pertinent information not otherwise captured by the CRF also was recordable as free text.

Gene Expression Testing
Gene expression testing was carried out at the time of specimen submission in the prior study¹² as described previously.¹⁴ Briefly, formalin-fixed, paraffin-embedded, unstained tissue sections and/or tissue blocks were submitted for testing along with a single hematoxylin and eosin–stained slide used to identify and designate the representative portion(s) of the lesion to be tested. These areas were macrodissected from unstained tissue sections and pooled for RNA extraction. Expression of 14 biomarker genes and 9 reference genes was measured via quantitative reverse transcription–polymerase chain reaction, performed in triplicate for each individual gene. The assay score was generated through application of a weighted algorithm to the expression values generated through quantitative reverse transcription–polymerase chain reaction. Scores were plotted on a scale ranging from −16.7 to 11.1, with scores from 0.0 to 11.1 classified as malignant, scores from −16.7 to −2.1 as benign, and scores from −2.1 to −0.1 as indeterminate.

Statistical Analysis
Demographic and other baseline characteristics of the patient population were summarized. Follow-up time was calculated as the interval between the date a patient’s gene expression test result was first issued to the provider and the date of the patient’s last recorded visit during the study period. All patient dermatology office visits within the designated follow-up period were documented, with a nonstandard number of visits and follow-up time across all study patients. Statistical analyses were conducted using SAS software (SAS Institute Inc), R software version 3.5.0 (R Foundation for Statistical Computing), and IBM SPSS Statistics software (IBM SPSS Statistics for Windows, Version 25).

 

Results

Patient Sample
A total of 25 ambiguous melanocytic neoplasms from 25 patients met the study inclusion criteria of a benign gene expression result with subsequent treatment as a benign neoplasm during follow-up. The patient sample statistics are summarized in Table 1. Most patients were younger than 65 years, with an average age at the time of biopsy of 48.4 years. All 25 neoplasms produced negative (benign) gene expression signature scores, all were diagnosed as benign nevi posttest by the submitting dermatopathologist, and all patients were initially treated in accordance with the benign diagnosis by the dermatologist(s) involved in clinical follow-up care. Prior to testing with the gene expression signature, most of these histopathologically indeterminate lesions received differential diagnoses, the most common of which were dysplastic nevus (84%), melanoma arising from a nevus (72%), and superficial spreading melanoma (64%; eTable). After testing with the gene expression signature and receiving a benign score, most lesions received a single differential diagnosis of dysplastic nevus (88%).

Follow-up and Survival
Clinical follow-up time ranged from 0.6 to 53.3 months, with a mean duration (SD) of 38.5 (16.6) months, and patients attended an average of 4 postbiopsy dermatology appointments (mean [SD], 4.6 [3.6]). According to the participating dermatology care providers, none of the 25 patients developed any indication during follow-up that the diagnosis of benign nevus was inaccurate. No patient had evidence of locally recurrent or metastatic melanoma, and none died during the study period.

Treatment/Interventions
The treatment recorded in the CRF was examination only for 21 of 25 patients, excision for 3, and other for 1 (Table 2). Because the explanation for the selection of other in this case described an excision performed at the same anatomic location as the biopsy, this treatment also was considered an excision for purposes of the study analyses. The 3 excisions all occurred at the first postbiopsy dermatology encounter. Across all follow-up visits, no additional surgical interventions occurred (Table 2).

The first excision (case 1) involved a 67-year-old woman with a lesion on the mid pubic region described clinically as an atypical nevus that generated a pretest histopathologic differential diagnosis including dysplastic nevus, superficial spreading melanoma, and melanoma arising within a nevus (Table 3; Figure, A and B). The gene expression test result was benign (score, −5.4), and the final pathology report diagnosis was nevus with junctional dysplasia, moderate. Surgical excision was performed at the patient’s first return visit, 505 days after initial diagnosis, with moderately dysplastic nevus as the recorded indication for removal. No repigmentation or other evidence of local recurrence or progression was detected, and the treating dermatologist indicated no suspicion that the original diagnosis of benign nevus was incorrect during the 23-month follow-up period.

The second excision (case 2) involved a 27-year-old woman with a pigmented neoplasm on the mid upper back (Figure, C and D) biopsied to rule out dysplastic nevus that resulted in a pretest histopathologic differential diagnosis of dysplastic nevus vs superficial spreading melanoma or melanoma arising within a nevus. The gene expression test result classified the lesion as benign (score, −2.9), and the final pathology diagnosis was nevus, compound, with moderate dysplasia. Despite the benign diagnosis, residual neoplasm (or pigmentation) at the biopsy site prompted the patient to request excision at her first postbiopsy visit, 22 days after testing (Table 3). The CRF completed by the dermatologist reported no indication that the benign diagnosis was inaccurate, but the patient was subsequently lost to follow-up.

The third excision (case 3) involved a 32-year-old woman with a pigmented lesion on the abdomen (Table 3; Figure, E and F). The clinical description was irregular-appearing black papule, nevus with atypia, and the histopathologic differential diagnosis again included dysplastic nevus, superficial spreading melanoma, and melanoma arising within a preexisting nevus. The gene expression signature result was benign (score, −7.2), and the final diagnosis issued within the accompanying pathology report was nevus with moderate junctional dysplasia. Despite the benign diagnosis, excision was performed 89 days after test result availability, with apparent residual pigmentation as the specified indication. As with the other 2 cases, the treating dermatologist confirmed that neither clinical features nor follow-up events suggested malignancy.

Comment

This study followed a cohort of 25 patients with histopathologically ambiguous melanocytic neoplasms that were classified as benign by a diagnostic gene expression test with the intent of determining the outcomes of patients whose treatment aligned with their benign test result. All patients initially were managed according to their test result. During an average posttest clinical follow-up time of more than 3 years (38.5 months), the 25 biopsied lesions, most of which received a differential diagnosis of dysplastic nevus, were regarded as benign nevi by their dermatologists, and the vast majority (88%) received no further surgical intervention. Three patients underwent subsequent excision of the biopsied lesion, with patient or physician preference as the indication in each instance. None of the 25 patients developed evidence of local recurrence, metastasis, or other findings that prompted doubt of the benign diagnosis. The absence of adverse events during clinical follow-up, particularly given that most lesions were not subjected to further intervention, supports use of the gene expression test as a safe and effective adjunct to the diagnosis and treatment of ambiguous melanocytic neoplasms by dermatologists and dermatopathologists.

 

Ambiguous melanocytic neoplasms evaluated without the aid of molecular adjuncts often result in equivocal or less-than-definitive diagnoses, and further surgical intervention is commonly undertaken to mitigate against the possibility of a missed melanoma.¹³ In this study, treatment that was aligned with the benign test result allowed most patients to avoid further surgical intervention, which suggests that adjunctive use of the gene signature can contribute to reductions in the physical and economic burdens imposed by unnecessary surgical interventions.^15,16 Moreover, any means of increasing accurate and definitive diagnoses may produce an immediate impact on health outcomes by reducing the anxiety that uncertainty often provokes in patients and health care providers alike.

Study Limitations
This study must be interpreted within the context of its limitations. Obtaining meaningful patient outcome data is a common challenge in health care research due to the requisite length of follow-up and sometimes the lack of definitive evidence of adverse events. This is particularly difficult for melanocytic neoplasms because of an apparent inclination for patients with benign diagnoses to abandon follow-up and an increasing tendency for even minimal diagnostic uncertainty to prompt complete excision. Additionally, the only definitive clinical outcome for melanocytic neoplasms is distant metastasis, which (fortunately for patients) is relatively rare. Not surprisingly, studies documenting clinical outcomes of patients with ambiguous melanocytic neoplasms tested prospectively with diagnostic adjuncts are scarce, and this study’s sample size and clinical follow-up compare favorably with the few that exist.^17,18 Although most melanomas declare themselves through recurrence or metastasis within several years of initial biopsy,^1,19 some are clinically dormant for as long as 10 years after initial detection.^20,21 This may be particularly true for the small or early-stage lesions that now comprise the majority of biopsied neoplasms, and such events would go undetected by this study and many others. It also must be recognized that uneventful follow-up, regardless of duration, cannot prove that a biopsied melanocytic neoplasm was benign. Although only 5 patients had a follow-up time of less than 2 years (the time frame in which most recurrence or metastasis will occur), it cannot be definitively proven that a minimum of 2 years recurrence- or metastasis-free survival indicates a benign lesion. Many early-stage malignant melanomas are eradicated by complete excision or even by the initial biopsy if margins are uninvolved.

Because these limitations are intrinsic to melanocytic neoplasms and current management strategies, they pertain to all investigations seeking insights into biological potential through clinical outcomes. Similarly, all current diagnostic tools and procedures have the potential for sampling error, including histopathology. The rarity of adverse outcomes (recurrence and metastasis) in patients with benign test results within this cohort indicates that false-negative results are uncommon, which is further evidenced by a similar rarity of adverse events in prior studies of the gene expression signature.^8-10,22 A particular strength of this study is that most of the ambiguous melanocytic neoplasms followed did not undergo excision after the initial biopsy, an increasingly uncommon situation that may increase their likelihood to be informative.

It must be emphasized that the gene expression test, similar to other diagnostic adjuncts, is neither a replacement for histopathologic interpretation nor a substitute for judgment. As with all tests, it can produce false-positive and false-negative results. Therefore, it should always be interpreted within the constellation of the many other data points that must be considered when making a distinction between benign nevus and malignant melanoma, including but not limited to patient age, family and personal history of melanoma, anatomic location, clinical features, and histopathologic findings. As is the case for many diseases, careful consideration of all relevant input is necessary to minimize the risk of misdiagnosis that might occur should any single data point prove inaccurate, including the results of adjunctive molecular tests.

Conclusion

Ancillary methods are emerging as useful tools for the diagnostic evaluation of melanocytic neoplasms that cannot be assigned definitive diagnoses using traditional techniques alone. This study suggests that patients with ambiguous melanocytic neoplasms may benefit from diagnoses and treatment decisions aligned with the results of a gene expression test, and that for those with a benign result, simple observation may be a safe alternative to surgical excision. This expands upon prior observations of the test’s influence on diagnoses and treatment decisions and supports its role as part of dermatopathologists’ and dermatologists’ decision-making process for histopathologically ambiguous melanocytic lesions.

The Diagnosis: Seborrheic Keratosis-like Melanoma 

Seborrheic keratosis (SK) is a benign neoplasm commonly encountered on the skin and frequently diagnosed by clinical examination alone. Seborrheic keratosis-like melanomas are melanomas that clinically or dermatoscopically resemble SKs and thus can be challenging to accurately diagnose. Melanomas can have a hyperkeratotic or verrucous appearance^1-3 and can even exhibit dermatoscopic and microscopic features that are found in SKs such as comedolike openings and milialike cysts as well as acanthosis and pseudohorn cysts, respectively.²  

In our patient, histopathology revealed SK-like architecture with hyperorthokeratosis, papillomatosis, pseudohorn cyst formation, and basaloid acanthosis (Figure). However, within the lesion was an asymmetric proliferation of nested atypical melanocytes with melanin pigment production. The atypical melanocytes filled and expanded papillomatous projections without notable pagetoid growth and extended into the dermis. There was a background congenital nevus component. These findings were diagnostic of invasive malignant melanoma, extending to a Breslow depth of 5.5 mm. A follow-up sentinel lymph node biopsy was negative for metastatic melanoma. The clinical and histologic findings did not show melanoma in the surrounding skin to suggest colonization of an SK by an adjacent melanoma. The clinical history of a long-standing lesion in conjunction with a congenital nevus component on histology favored a diagnosis of melanoma arising in association with a congenital nevus with an SK-like architecture rather than arising in a preexisting SK or de novo melanoma.  

Because our patient did not have multiple widespread SKs and reported rapid growth in the lesion in the last 6 months, there was concern for a malignant neoplasm. However, in patients with numerous SKs or areas of chronically sun-damaged skin, it can be difficult to identify suspicious lesions. It is important for clinicians to remain aware of SK-like melanomas and have a lower threshold for biopsy of any changing or symptomatic lesion that clinically resembles an SK. In our case, the history of change and the markedly different clinical appearance of the lesion in comparison to our patient's SKs prompted the biopsy. Criteria have been proposed to help differentiate these entities under dermoscopy, with melanoma showing the presence of the blue-black sign, pigment network, pseudopods or streaks, and/or the blue-white veil.⁴ 

Cutaneous metastases classically present as dermal nodules, plaques, or ulcers.^5,6 A rare pigmented case of metastatic breast adenocarcinoma clinically mimicking melanoma has been reported.⁷ There is limited literature on the dermoscopic features of cutaneous metastases, but it appears that polymorphic vascular patterns are most common.^5,8 The possibility of a metastatic melanoma involving an SK is a theoretical consideration, but there was no prior history of melanoma in our patient, and the histologic findings were consistent with primary melanoma. There was no histologic evidence of pigmented metastatic breast carcinoma or metastatic lung carcinoma.  

Pigmented malignant hidroacanthoma simplex and pigmented porocarcinomas are rare malignant sweat gland tumors.^9-11 Their benign counterparts are the more commonly encountered hidroacanthoma simplex (intraepidermal poroma) and poroma. Pigmented malignant hidroacanthoma simplex has been reported to clinically mimic an irritated SK.¹⁰ The histopathology of our case did not have features of malignant hidroacanthoma simplex or porocarcinoma. Pigmented squamous cell carcinoma is an uncommon variant of squamous cell carcinoma, and histopathology would reveal proliferation of atypical keratinocytes.¹²  

The Diagnosis: Seborrheic Keratosis-like Melanoma 

Seborrheic keratosis (SK) is a benign neoplasm commonly encountered on the skin and frequently diagnosed by clinical examination alone. Seborrheic keratosis-like melanomas are melanomas that clinically or dermatoscopically resemble SKs and thus can be challenging to accurately diagnose. Melanomas can have a hyperkeratotic or verrucous appearance^1-3 and can even exhibit dermatoscopic and microscopic features that are found in SKs such as comedolike openings and milialike cysts as well as acanthosis and pseudohorn cysts, respectively.²  

In our patient, histopathology revealed SK-like architecture with hyperorthokeratosis, papillomatosis, pseudohorn cyst formation, and basaloid acanthosis (Figure). However, within the lesion was an asymmetric proliferation of nested atypical melanocytes with melanin pigment production. The atypical melanocytes filled and expanded papillomatous projections without notable pagetoid growth and extended into the dermis. There was a background congenital nevus component. These findings were diagnostic of invasive malignant melanoma, extending to a Breslow depth of 5.5 mm. A follow-up sentinel lymph node biopsy was negative for metastatic melanoma. The clinical and histologic findings did not show melanoma in the surrounding skin to suggest colonization of an SK by an adjacent melanoma. The clinical history of a long-standing lesion in conjunction with a congenital nevus component on histology favored a diagnosis of melanoma arising in association with a congenital nevus with an SK-like architecture rather than arising in a preexisting SK or de novo melanoma.  

Because our patient did not have multiple widespread SKs and reported rapid growth in the lesion in the last 6 months, there was concern for a malignant neoplasm. However, in patients with numerous SKs or areas of chronically sun-damaged skin, it can be difficult to identify suspicious lesions. It is important for clinicians to remain aware of SK-like melanomas and have a lower threshold for biopsy of any changing or symptomatic lesion that clinically resembles an SK. In our case, the history of change and the markedly different clinical appearance of the lesion in comparison to our patient's SKs prompted the biopsy. Criteria have been proposed to help differentiate these entities under dermoscopy, with melanoma showing the presence of the blue-black sign, pigment network, pseudopods or streaks, and/or the blue-white veil.⁴ 

Cutaneous metastases classically present as dermal nodules, plaques, or ulcers.^5,6 A rare pigmented case of metastatic breast adenocarcinoma clinically mimicking melanoma has been reported.⁷ There is limited literature on the dermoscopic features of cutaneous metastases, but it appears that polymorphic vascular patterns are most common.^5,8 The possibility of a metastatic melanoma involving an SK is a theoretical consideration, but there was no prior history of melanoma in our patient, and the histologic findings were consistent with primary melanoma. There was no histologic evidence of pigmented metastatic breast carcinoma or metastatic lung carcinoma.  

Pigmented malignant hidroacanthoma simplex and pigmented porocarcinomas are rare malignant sweat gland tumors.^9-11 Their benign counterparts are the more commonly encountered hidroacanthoma simplex (intraepidermal poroma) and poroma. Pigmented malignant hidroacanthoma simplex has been reported to clinically mimic an irritated SK.¹⁰ The histopathology of our case did not have features of malignant hidroacanthoma simplex or porocarcinoma. Pigmented squamous cell carcinoma is an uncommon variant of squamous cell carcinoma, and histopathology would reveal proliferation of atypical keratinocytes.¹²  

The Diagnosis: Seborrheic Keratosis-like Melanoma 

Seborrheic keratosis (SK) is a benign neoplasm commonly encountered on the skin and frequently diagnosed by clinical examination alone. Seborrheic keratosis-like melanomas are melanomas that clinically or dermatoscopically resemble SKs and thus can be challenging to accurately diagnose. Melanomas can have a hyperkeratotic or verrucous appearance^1-3 and can even exhibit dermatoscopic and microscopic features that are found in SKs such as comedolike openings and milialike cysts as well as acanthosis and pseudohorn cysts, respectively.²  

In our patient, histopathology revealed SK-like architecture with hyperorthokeratosis, papillomatosis, pseudohorn cyst formation, and basaloid acanthosis (Figure). However, within the lesion was an asymmetric proliferation of nested atypical melanocytes with melanin pigment production. The atypical melanocytes filled and expanded papillomatous projections without notable pagetoid growth and extended into the dermis. There was a background congenital nevus component. These findings were diagnostic of invasive malignant melanoma, extending to a Breslow depth of 5.5 mm. A follow-up sentinel lymph node biopsy was negative for metastatic melanoma. The clinical and histologic findings did not show melanoma in the surrounding skin to suggest colonization of an SK by an adjacent melanoma. The clinical history of a long-standing lesion in conjunction with a congenital nevus component on histology favored a diagnosis of melanoma arising in association with a congenital nevus with an SK-like architecture rather than arising in a preexisting SK or de novo melanoma.  

Because our patient did not have multiple widespread SKs and reported rapid growth in the lesion in the last 6 months, there was concern for a malignant neoplasm. However, in patients with numerous SKs or areas of chronically sun-damaged skin, it can be difficult to identify suspicious lesions. It is important for clinicians to remain aware of SK-like melanomas and have a lower threshold for biopsy of any changing or symptomatic lesion that clinically resembles an SK. In our case, the history of change and the markedly different clinical appearance of the lesion in comparison to our patient's SKs prompted the biopsy. Criteria have been proposed to help differentiate these entities under dermoscopy, with melanoma showing the presence of the blue-black sign, pigment network, pseudopods or streaks, and/or the blue-white veil.⁴ 

Cutaneous metastases classically present as dermal nodules, plaques, or ulcers.^5,6 A rare pigmented case of metastatic breast adenocarcinoma clinically mimicking melanoma has been reported.⁷ There is limited literature on the dermoscopic features of cutaneous metastases, but it appears that polymorphic vascular patterns are most common.^5,8 The possibility of a metastatic melanoma involving an SK is a theoretical consideration, but there was no prior history of melanoma in our patient, and the histologic findings were consistent with primary melanoma. There was no histologic evidence of pigmented metastatic breast carcinoma or metastatic lung carcinoma.  

Pigmented malignant hidroacanthoma simplex and pigmented porocarcinomas are rare malignant sweat gland tumors.^9-11 Their benign counterparts are the more commonly encountered hidroacanthoma simplex (intraepidermal poroma) and poroma. Pigmented malignant hidroacanthoma simplex has been reported to clinically mimic an irritated SK.¹⁰ The histopathology of our case did not have features of malignant hidroacanthoma simplex or porocarcinoma. Pigmented squamous cell carcinoma is an uncommon variant of squamous cell carcinoma, and histopathology would reveal proliferation of atypical keratinocytes.¹²  

The Diagnosis: Sweet Syndrome 

Sweet syndrome, alternatively known as acute febrile neutrophilic dermatosis, typically presents with variably tender, erythematous papules, plaques, or nodules in middle-aged adults.¹ Systemic symptoms such as fever, fatigue, and arthralgia often accompany these cutaneous findings.^1,2 Although the pathophysiology has not been fully elucidated, this syndrome frequently is associated with infections, especially upper respiratory illnesses; medications; and malignancies. Among cases of malignancy-associated Sweet syndrome, hematologic malignancies, particularly acute myeloid leukemia and myelodysplastic syndrome, are more common than solid organ malignancies.^1,2 Sweet syndrome may precede the associated malignancy by several months; thus, patients without an identifiable trigger for Sweet syndrome should be closely followed.² Treatment with systemic steroids typically is effective.^1,3 Typical histologic features include papillary dermal edema and a brisk neutrophilic infiltrate in the superficial to mid dermis (quiz image).⁴ Overlying epidermal spongiosis with or without vesiculation also can be seen.⁴ Leukocytoclasia and endothelial swelling without fibrinoid necrosis are typical, though full-blown leukocytoclastic vasculitis can be seen.^3,4 A histiocytoid variant also has been described in which the dermal infiltrate is composed of mononuclear cells reminiscent of histiocytes that are thought to be immature cells of myeloid origin. This variant histologically can simulate leukemia cutis.⁵  

Perniosis, also known as chilblains, typically presents with red to violaceous macules or papules on acral sites, particularly the distal fingers and toes.^6,7 It tends to affect young women more frequently than other demographic groups. Although the pathophysiology is not fully understood, perniosis is thought to represent an abnormal inflammatory response to cold environmental conditions. It can occur as an idiopathic disorder or in association with various systemic illnesses including lupus erythematosus.^6,7 The typical histologic findings include papillary dermal edema and a lymphocytic infiltrate in the superficial to deep dermis, often with perivascular and perieccrine accentuation (Figure 1).^3,6 Other less common microscopic findings include sparse keratinocyte necrosis, basal layer vacuolar change, swelling of endothelial cells, and lymphocytic vasculitis.⁶ The lesions typically resolve spontaneously within a few weeks, but in some cases they may be chronic.³ 

Polymorphous light eruption, a common photodermatosis induced by UV light exposure, typically presents in adolescence or early adulthood with a female predominance. Patients usually develop this pruritic rash on sun-exposed skin other than the face and dorsal aspects of the hands in the spring or early summer upon increased sun exposure after the winter season.^3,8 Consistent sunlight exposure throughout the summer months results in decreased flares. Various cutaneous morphologies including papules, vesicles, and plaques can be seen.^3,8 Histologic findings include papillary dermal edema and a perivascular lymphocytic infiltrate in the superficial to deep dermis (Figure 2).⁴  

Tinea corporis, a superficial cutaneous dermatophyte infection, typically presents as annular scaly plaques with central clearing. Vesicles and pustules also can be seen.³ The diagnosis can be confirmed via fungal culture, identification of hyphae on microscopic examination of skin scrapings using potassium hydroxide, or cutaneous biopsy. Histologic clues to diagnosis include a "compact stratum corneum (either uniform or forming a layer beneath a basket weave stratum corneum), parakeratosis, mild spongiosis, and neutrophils in the stratum corneum" (Figure 3).⁹ Papillary dermal edema also may be present, though this finding less commonly is reported.^9,10 Because fungal hyphae can be difficult to identify on hematoxylin and eosin-stained slides, special stains such as periodic acid-Schiff or Grocott-Gomori methenamine-silver may be helpful.⁹ These infections are managed with topical or oral antifungal medications.  

Wells syndrome, also known as eosinophilic cellulitis, presents with an acute eruption that can clinically resemble bacterial cellulitis.³ It has been described in children and adults with various clinical morphologies including plaques, bullae, papulovesicles, and papulonodules. Peripheral eosinophilia may be present.¹¹ The clinical lesions usually resolve spontaneously in a few weeks to months, but recurrences are typical.^3,11 Histologic findings include papillary dermal edema with or without subepidermal bulla formation and epidermal spongiosis as well as a mixed inflammatory infiltrate with a predominance of eosinophils and flame figures (Figure 4).⁴ Flame figures are collagen fibers coated with major basic protein and other constituents of degranulated eosinophils.³ Although flame figures often are present in Wells syndrome, they are not specific to this condition.^3,4 Some consider Wells syndrome an exaggerated reaction pattern rather than a specific entity.³ 

The Diagnosis: Sweet Syndrome 

Sweet syndrome, alternatively known as acute febrile neutrophilic dermatosis, typically presents with variably tender, erythematous papules, plaques, or nodules in middle-aged adults.¹ Systemic symptoms such as fever, fatigue, and arthralgia often accompany these cutaneous findings.^1,2 Although the pathophysiology has not been fully elucidated, this syndrome frequently is associated with infections, especially upper respiratory illnesses; medications; and malignancies. Among cases of malignancy-associated Sweet syndrome, hematologic malignancies, particularly acute myeloid leukemia and myelodysplastic syndrome, are more common than solid organ malignancies.^1,2 Sweet syndrome may precede the associated malignancy by several months; thus, patients without an identifiable trigger for Sweet syndrome should be closely followed.² Treatment with systemic steroids typically is effective.^1,3 Typical histologic features include papillary dermal edema and a brisk neutrophilic infiltrate in the superficial to mid dermis (quiz image).⁴ Overlying epidermal spongiosis with or without vesiculation also can be seen.⁴ Leukocytoclasia and endothelial swelling without fibrinoid necrosis are typical, though full-blown leukocytoclastic vasculitis can be seen.^3,4 A histiocytoid variant also has been described in which the dermal infiltrate is composed of mononuclear cells reminiscent of histiocytes that are thought to be immature cells of myeloid origin. This variant histologically can simulate leukemia cutis.⁵  

Perniosis, also known as chilblains, typically presents with red to violaceous macules or papules on acral sites, particularly the distal fingers and toes.^6,7 It tends to affect young women more frequently than other demographic groups. Although the pathophysiology is not fully understood, perniosis is thought to represent an abnormal inflammatory response to cold environmental conditions. It can occur as an idiopathic disorder or in association with various systemic illnesses including lupus erythematosus.^6,7 The typical histologic findings include papillary dermal edema and a lymphocytic infiltrate in the superficial to deep dermis, often with perivascular and perieccrine accentuation (Figure 1).^3,6 Other less common microscopic findings include sparse keratinocyte necrosis, basal layer vacuolar change, swelling of endothelial cells, and lymphocytic vasculitis.⁶ The lesions typically resolve spontaneously within a few weeks, but in some cases they may be chronic.³ 

Polymorphous light eruption, a common photodermatosis induced by UV light exposure, typically presents in adolescence or early adulthood with a female predominance. Patients usually develop this pruritic rash on sun-exposed skin other than the face and dorsal aspects of the hands in the spring or early summer upon increased sun exposure after the winter season.^3,8 Consistent sunlight exposure throughout the summer months results in decreased flares. Various cutaneous morphologies including papules, vesicles, and plaques can be seen.^3,8 Histologic findings include papillary dermal edema and a perivascular lymphocytic infiltrate in the superficial to deep dermis (Figure 2).⁴  

Tinea corporis, a superficial cutaneous dermatophyte infection, typically presents as annular scaly plaques with central clearing. Vesicles and pustules also can be seen.³ The diagnosis can be confirmed via fungal culture, identification of hyphae on microscopic examination of skin scrapings using potassium hydroxide, or cutaneous biopsy. Histologic clues to diagnosis include a "compact stratum corneum (either uniform or forming a layer beneath a basket weave stratum corneum), parakeratosis, mild spongiosis, and neutrophils in the stratum corneum" (Figure 3).⁹ Papillary dermal edema also may be present, though this finding less commonly is reported.^9,10 Because fungal hyphae can be difficult to identify on hematoxylin and eosin-stained slides, special stains such as periodic acid-Schiff or Grocott-Gomori methenamine-silver may be helpful.⁹ These infections are managed with topical or oral antifungal medications.  

Wells syndrome, also known as eosinophilic cellulitis, presents with an acute eruption that can clinically resemble bacterial cellulitis.³ It has been described in children and adults with various clinical morphologies including plaques, bullae, papulovesicles, and papulonodules. Peripheral eosinophilia may be present.¹¹ The clinical lesions usually resolve spontaneously in a few weeks to months, but recurrences are typical.^3,11 Histologic findings include papillary dermal edema with or without subepidermal bulla formation and epidermal spongiosis as well as a mixed inflammatory infiltrate with a predominance of eosinophils and flame figures (Figure 4).⁴ Flame figures are collagen fibers coated with major basic protein and other constituents of degranulated eosinophils.³ Although flame figures often are present in Wells syndrome, they are not specific to this condition.^3,4 Some consider Wells syndrome an exaggerated reaction pattern rather than a specific entity.³ 

The Diagnosis: Sweet Syndrome 

Sweet syndrome, alternatively known as acute febrile neutrophilic dermatosis, typically presents with variably tender, erythematous papules, plaques, or nodules in middle-aged adults.¹ Systemic symptoms such as fever, fatigue, and arthralgia often accompany these cutaneous findings.^1,2 Although the pathophysiology has not been fully elucidated, this syndrome frequently is associated with infections, especially upper respiratory illnesses; medications; and malignancies. Among cases of malignancy-associated Sweet syndrome, hematologic malignancies, particularly acute myeloid leukemia and myelodysplastic syndrome, are more common than solid organ malignancies.^1,2 Sweet syndrome may precede the associated malignancy by several months; thus, patients without an identifiable trigger for Sweet syndrome should be closely followed.² Treatment with systemic steroids typically is effective.^1,3 Typical histologic features include papillary dermal edema and a brisk neutrophilic infiltrate in the superficial to mid dermis (quiz image).⁴ Overlying epidermal spongiosis with or without vesiculation also can be seen.⁴ Leukocytoclasia and endothelial swelling without fibrinoid necrosis are typical, though full-blown leukocytoclastic vasculitis can be seen.^3,4 A histiocytoid variant also has been described in which the dermal infiltrate is composed of mononuclear cells reminiscent of histiocytes that are thought to be immature cells of myeloid origin. This variant histologically can simulate leukemia cutis.⁵  

Perniosis, also known as chilblains, typically presents with red to violaceous macules or papules on acral sites, particularly the distal fingers and toes.^6,7 It tends to affect young women more frequently than other demographic groups. Although the pathophysiology is not fully understood, perniosis is thought to represent an abnormal inflammatory response to cold environmental conditions. It can occur as an idiopathic disorder or in association with various systemic illnesses including lupus erythematosus.^6,7 The typical histologic findings include papillary dermal edema and a lymphocytic infiltrate in the superficial to deep dermis, often with perivascular and perieccrine accentuation (Figure 1).^3,6 Other less common microscopic findings include sparse keratinocyte necrosis, basal layer vacuolar change, swelling of endothelial cells, and lymphocytic vasculitis.⁶ The lesions typically resolve spontaneously within a few weeks, but in some cases they may be chronic.³ 

Polymorphous light eruption, a common photodermatosis induced by UV light exposure, typically presents in adolescence or early adulthood with a female predominance. Patients usually develop this pruritic rash on sun-exposed skin other than the face and dorsal aspects of the hands in the spring or early summer upon increased sun exposure after the winter season.^3,8 Consistent sunlight exposure throughout the summer months results in decreased flares. Various cutaneous morphologies including papules, vesicles, and plaques can be seen.^3,8 Histologic findings include papillary dermal edema and a perivascular lymphocytic infiltrate in the superficial to deep dermis (Figure 2).⁴  

Tinea corporis, a superficial cutaneous dermatophyte infection, typically presents as annular scaly plaques with central clearing. Vesicles and pustules also can be seen.³ The diagnosis can be confirmed via fungal culture, identification of hyphae on microscopic examination of skin scrapings using potassium hydroxide, or cutaneous biopsy. Histologic clues to diagnosis include a "compact stratum corneum (either uniform or forming a layer beneath a basket weave stratum corneum), parakeratosis, mild spongiosis, and neutrophils in the stratum corneum" (Figure 3).⁹ Papillary dermal edema also may be present, though this finding less commonly is reported.^9,10 Because fungal hyphae can be difficult to identify on hematoxylin and eosin-stained slides, special stains such as periodic acid-Schiff or Grocott-Gomori methenamine-silver may be helpful.⁹ These infections are managed with topical or oral antifungal medications.  

Wells syndrome, also known as eosinophilic cellulitis, presents with an acute eruption that can clinically resemble bacterial cellulitis.³ It has been described in children and adults with various clinical morphologies including plaques, bullae, papulovesicles, and papulonodules. Peripheral eosinophilia may be present.¹¹ The clinical lesions usually resolve spontaneously in a few weeks to months, but recurrences are typical.^3,11 Histologic findings include papillary dermal edema with or without subepidermal bulla formation and epidermal spongiosis as well as a mixed inflammatory infiltrate with a predominance of eosinophils and flame figures (Figure 4).⁴ Flame figures are collagen fibers coated with major basic protein and other constituents of degranulated eosinophils.³ Although flame figures often are present in Wells syndrome, they are not specific to this condition.^3,4 Some consider Wells syndrome an exaggerated reaction pattern rather than a specific entity.³ 

The Diagnosis: Bullous Amyloidosis 

A punch biopsy from the left temple showed deposits of amorphous eosinophilic material at the tips of dermal papillae and in the papillary dermis with hemorrhage present (Figure 1). A diagnosis of amyloidosis was confirmed on the biopsy of the skin bulla. The low κ/λ light chain ratio and M-spike with notably elevated free λ light chains in both serum and urine were consistent with a λ light chain primary systemic amyloidosis. The patient was seen by hematology and oncology. A bone marrow biopsy demonstrated that 15% to 20% of the clonal-cell population was λ light chain restricted. Eosinophilic extracellular deposits found in the adjacent soft tissue and bone marrow space were confirmed as amyloid with apple green birefringence under polarized light on Congo red stain and metachromatic staining with crystal violet. The patient ultimately was diagnosed with λ light chain multiple myeloma and primary systemic amyloidosis. 

Our patient was treated with a combination therapy of bortezomib, cyclophosphamide, and dexamethasone on 21-day cycles, with bortezomib on days 1, 4, 8, and 11. She had received 3 cycles of chemotherapy before developing diarrhea, hypotension, acute on chronic heart failure, and acute renal failure requiring hospitalization. She had several related complications due to amyloid light chain (AL) amyloidosis and subsequently died 16 days after her initial hospitalization from complications of methicillin-resistant Staphylococcus aureus bacteremia and septic shock. 

Amyloidosis is the pathologic deposition of abnormal protein in the extracellular space of any tissue. Various soluble precursor proteins can make up amyloid, and these proteins polymerize into insoluble fibrils that damage the surrounding parenchyma. The clinical presentation of amyloidosis varies depending on the affected tissue as well as the constituent protein. The amyloidoses are divided into localized cutaneous, primary systemic, and secondary systemic variants. The initial distinction in amyloidosis is determining whether it is skin limited or systemic. Localized cutaneous amyloidosis comprises 30% to 40% of all amyloidosis cases and is further divided into 3 main subtypes: macular, lichen, and nodular amyloidosis.¹ Macular and lichen amyloidosis are composed of keratin derivatives and typically are induced by patients when rubbing or scratching the skin. Histologically, macular and lichen amyloidosis are restricted to the superficial papillary dermis.¹ Nodular amyloidosis is composed of λ or κ light chain immunoglobulins, which are produced by cutaneous infiltrates of monoclonal plasma cells. Histologically, nodular amyloidosis is characterized by a diffuse dermal infiltrate of amorphous eosinophilic material.¹ Primary systemic amyloidosis is associated with an underlying plasma cell dyscrasia, and unlike secondary keratinocyte-derived amyloid, it can involve internal organs. Similar to nodular amyloidosis, primary systemic amyloidosis is composed of AL proteins, and it is histologically similar to nodular amyloidosis.¹ 

Primary systemic AL amyloidosis commonly affects individuals aged 50 to 60 years. Males and females are equally affected. Macroglossia and periorbital purpura are some of the pathognomonic presentations in AL amyloidosis. The major cause of death in these patients is cardiac and renal involvement. Renal involvement commonly presents as nephrotic syndrome, and cardiac involvement can present as a restrictive cardiomyopathy with dyspnea. Other symptoms include edema, hepatosplenomegaly, bleeding diathesis, and carpal tunnel syndrome.² An evaluation for AL amyloidosis should include a complete review of systems and physical examination with studies such as complete blood cell count, comprehensive metabolic panel, serum and urine protein electrophoresis and immunofixation, and electrocardiogram. 

Cutaneous involvement in AL amyloidosis most commonly includes yellowish waxy papules, nodules, and plaques but also can include purpura and petechiae.² Bullous amyloidosis, as seen in our patient, is a rare cutaneous presentation of AL amyloidosis that usually is negative for the Nikolsky sign (Figure 2). Bullae form due to weakness in amyloid-laden dermal connective tissue.³ Eighty-eight percent of cases of bullous amyloidosis have systemic involvement.¹ Some cases have reported a familial linkage, suggesting there might be a genetic component to the disease.⁴ A PubMed search of articles indexed for MEDLINE using the terms bullous amyloidosis, bullous, amyloidosis, and amyloid revealed fewer than 35 cases of bullous amyloidosis in the English-language literature.⁵ Bullae can be located intradermally or subepidermally and commonly are hemorrhagic but also can be translucent, tender, and tense. 

A study of electron microscopy in a patient with systemic bullous amyloidosis demonstrated amyloid and keratinocyte protrusions that perforated the dermis through the spaces in the lamina densa. The study concluded that the disintegration of the lamina densa and expansion of the intercellular spaces between keratinocytes were the causes of skin fragility as well as fluid exudation.⁵ Trauma or friction to the skin are local precipitating factors for blister formation in bullous amyloidosis.  

Bullae can become apparent at any stage of AL amyloidosis, but they generally increase in size and number over time and are most common in intertriginous areas. Bullous amyloid lesions, especially those located in intertriginous areas, can have secondary impetiginization.⁶ In many cases, patients who present with bullous amyloidosis ultimately will be diagnosed with multiple myeloma or another plasma cell dyscrasia. In AL amyloidosis, only 10% to 15% of cases meet criteria for multiple myeloma, whereas 80% or more patients have a monoclonal gammopathy of undetermined significance.⁷  

The prognosis of cutaneous amyloidosis depends on the extent of organ involvement and response to treatment. Treatment is aimed at eliminating clonal plasma cell populations to decrease the production of light chains, thereby decreasing protein burden and amyloid progression. Historically, treatment options included cytotoxic chemotherapy such as oral melphalan and dexamethasone, followed by hematopoietic stem cell transplant. More recent treatment options include bortezomib, thalidomide, pomalidomide, and lenalidomide.⁸ Our patient received a regimen of bortezomib, cyclophosphamide, and dexamethasone that is used for patients with extensive multiple myeloma.  

The differential diagnosis in our patient included bullous drug eruption, which should be considered if the bullae are reoccurring at the same location and in association with the administration of a culprit drug. Bullous pemphigoid is preceded by pruritus, and biopsy demonstrates subepidermal bullae with associated eosinophilic infiltrate. Epidermolysis bullosa acquisita can present with milia and a linear pattern along the basement membrane zone with direct immunofluorescence. Traumatic purpura usually present with the classic shape and hue of an ecchymosis, and the patient will have a history of trauma. 

Cutaneous involvement of amyloidosis can be an early clue to the diagnosis of plasma cell dyscrasia. Early diagnosis and treatment can portend a better prognosis and prevent progression to renal or cardiac disease. 

The Diagnosis: Bullous Amyloidosis 

A punch biopsy from the left temple showed deposits of amorphous eosinophilic material at the tips of dermal papillae and in the papillary dermis with hemorrhage present (Figure 1). A diagnosis of amyloidosis was confirmed on the biopsy of the skin bulla. The low κ/λ light chain ratio and M-spike with notably elevated free λ light chains in both serum and urine were consistent with a λ light chain primary systemic amyloidosis. The patient was seen by hematology and oncology. A bone marrow biopsy demonstrated that 15% to 20% of the clonal-cell population was λ light chain restricted. Eosinophilic extracellular deposits found in the adjacent soft tissue and bone marrow space were confirmed as amyloid with apple green birefringence under polarized light on Congo red stain and metachromatic staining with crystal violet. The patient ultimately was diagnosed with λ light chain multiple myeloma and primary systemic amyloidosis. 

Our patient was treated with a combination therapy of bortezomib, cyclophosphamide, and dexamethasone on 21-day cycles, with bortezomib on days 1, 4, 8, and 11. She had received 3 cycles of chemotherapy before developing diarrhea, hypotension, acute on chronic heart failure, and acute renal failure requiring hospitalization. She had several related complications due to amyloid light chain (AL) amyloidosis and subsequently died 16 days after her initial hospitalization from complications of methicillin-resistant Staphylococcus aureus bacteremia and septic shock. 

Amyloidosis is the pathologic deposition of abnormal protein in the extracellular space of any tissue. Various soluble precursor proteins can make up amyloid, and these proteins polymerize into insoluble fibrils that damage the surrounding parenchyma. The clinical presentation of amyloidosis varies depending on the affected tissue as well as the constituent protein. The amyloidoses are divided into localized cutaneous, primary systemic, and secondary systemic variants. The initial distinction in amyloidosis is determining whether it is skin limited or systemic. Localized cutaneous amyloidosis comprises 30% to 40% of all amyloidosis cases and is further divided into 3 main subtypes: macular, lichen, and nodular amyloidosis.¹ Macular and lichen amyloidosis are composed of keratin derivatives and typically are induced by patients when rubbing or scratching the skin. Histologically, macular and lichen amyloidosis are restricted to the superficial papillary dermis.¹ Nodular amyloidosis is composed of λ or κ light chain immunoglobulins, which are produced by cutaneous infiltrates of monoclonal plasma cells. Histologically, nodular amyloidosis is characterized by a diffuse dermal infiltrate of amorphous eosinophilic material.¹ Primary systemic amyloidosis is associated with an underlying plasma cell dyscrasia, and unlike secondary keratinocyte-derived amyloid, it can involve internal organs. Similar to nodular amyloidosis, primary systemic amyloidosis is composed of AL proteins, and it is histologically similar to nodular amyloidosis.¹ 

Primary systemic AL amyloidosis commonly affects individuals aged 50 to 60 years. Males and females are equally affected. Macroglossia and periorbital purpura are some of the pathognomonic presentations in AL amyloidosis. The major cause of death in these patients is cardiac and renal involvement. Renal involvement commonly presents as nephrotic syndrome, and cardiac involvement can present as a restrictive cardiomyopathy with dyspnea. Other symptoms include edema, hepatosplenomegaly, bleeding diathesis, and carpal tunnel syndrome.² An evaluation for AL amyloidosis should include a complete review of systems and physical examination with studies such as complete blood cell count, comprehensive metabolic panel, serum and urine protein electrophoresis and immunofixation, and electrocardiogram. 

Cutaneous involvement in AL amyloidosis most commonly includes yellowish waxy papules, nodules, and plaques but also can include purpura and petechiae.² Bullous amyloidosis, as seen in our patient, is a rare cutaneous presentation of AL amyloidosis that usually is negative for the Nikolsky sign (Figure 2). Bullae form due to weakness in amyloid-laden dermal connective tissue.³ Eighty-eight percent of cases of bullous amyloidosis have systemic involvement.¹ Some cases have reported a familial linkage, suggesting there might be a genetic component to the disease.⁴ A PubMed search of articles indexed for MEDLINE using the terms bullous amyloidosis, bullous, amyloidosis, and amyloid revealed fewer than 35 cases of bullous amyloidosis in the English-language literature.⁵ Bullae can be located intradermally or subepidermally and commonly are hemorrhagic but also can be translucent, tender, and tense. 

A study of electron microscopy in a patient with systemic bullous amyloidosis demonstrated amyloid and keratinocyte protrusions that perforated the dermis through the spaces in the lamina densa. The study concluded that the disintegration of the lamina densa and expansion of the intercellular spaces between keratinocytes were the causes of skin fragility as well as fluid exudation.⁵ Trauma or friction to the skin are local precipitating factors for blister formation in bullous amyloidosis.  

Bullae can become apparent at any stage of AL amyloidosis, but they generally increase in size and number over time and are most common in intertriginous areas. Bullous amyloid lesions, especially those located in intertriginous areas, can have secondary impetiginization.⁶ In many cases, patients who present with bullous amyloidosis ultimately will be diagnosed with multiple myeloma or another plasma cell dyscrasia. In AL amyloidosis, only 10% to 15% of cases meet criteria for multiple myeloma, whereas 80% or more patients have a monoclonal gammopathy of undetermined significance.⁷  

The prognosis of cutaneous amyloidosis depends on the extent of organ involvement and response to treatment. Treatment is aimed at eliminating clonal plasma cell populations to decrease the production of light chains, thereby decreasing protein burden and amyloid progression. Historically, treatment options included cytotoxic chemotherapy such as oral melphalan and dexamethasone, followed by hematopoietic stem cell transplant. More recent treatment options include bortezomib, thalidomide, pomalidomide, and lenalidomide.⁸ Our patient received a regimen of bortezomib, cyclophosphamide, and dexamethasone that is used for patients with extensive multiple myeloma.  

The differential diagnosis in our patient included bullous drug eruption, which should be considered if the bullae are reoccurring at the same location and in association with the administration of a culprit drug. Bullous pemphigoid is preceded by pruritus, and biopsy demonstrates subepidermal bullae with associated eosinophilic infiltrate. Epidermolysis bullosa acquisita can present with milia and a linear pattern along the basement membrane zone with direct immunofluorescence. Traumatic purpura usually present with the classic shape and hue of an ecchymosis, and the patient will have a history of trauma. 

Cutaneous involvement of amyloidosis can be an early clue to the diagnosis of plasma cell dyscrasia. Early diagnosis and treatment can portend a better prognosis and prevent progression to renal or cardiac disease. 

The Diagnosis: Bullous Amyloidosis 

A punch biopsy from the left temple showed deposits of amorphous eosinophilic material at the tips of dermal papillae and in the papillary dermis with hemorrhage present (Figure 1). A diagnosis of amyloidosis was confirmed on the biopsy of the skin bulla. The low κ/λ light chain ratio and M-spike with notably elevated free λ light chains in both serum and urine were consistent with a λ light chain primary systemic amyloidosis. The patient was seen by hematology and oncology. A bone marrow biopsy demonstrated that 15% to 20% of the clonal-cell population was λ light chain restricted. Eosinophilic extracellular deposits found in the adjacent soft tissue and bone marrow space were confirmed as amyloid with apple green birefringence under polarized light on Congo red stain and metachromatic staining with crystal violet. The patient ultimately was diagnosed with λ light chain multiple myeloma and primary systemic amyloidosis. 

Our patient was treated with a combination therapy of bortezomib, cyclophosphamide, and dexamethasone on 21-day cycles, with bortezomib on days 1, 4, 8, and 11. She had received 3 cycles of chemotherapy before developing diarrhea, hypotension, acute on chronic heart failure, and acute renal failure requiring hospitalization. She had several related complications due to amyloid light chain (AL) amyloidosis and subsequently died 16 days after her initial hospitalization from complications of methicillin-resistant Staphylococcus aureus bacteremia and septic shock. 

Amyloidosis is the pathologic deposition of abnormal protein in the extracellular space of any tissue. Various soluble precursor proteins can make up amyloid, and these proteins polymerize into insoluble fibrils that damage the surrounding parenchyma. The clinical presentation of amyloidosis varies depending on the affected tissue as well as the constituent protein. The amyloidoses are divided into localized cutaneous, primary systemic, and secondary systemic variants. The initial distinction in amyloidosis is determining whether it is skin limited or systemic. Localized cutaneous amyloidosis comprises 30% to 40% of all amyloidosis cases and is further divided into 3 main subtypes: macular, lichen, and nodular amyloidosis.¹ Macular and lichen amyloidosis are composed of keratin derivatives and typically are induced by patients when rubbing or scratching the skin. Histologically, macular and lichen amyloidosis are restricted to the superficial papillary dermis.¹ Nodular amyloidosis is composed of λ or κ light chain immunoglobulins, which are produced by cutaneous infiltrates of monoclonal plasma cells. Histologically, nodular amyloidosis is characterized by a diffuse dermal infiltrate of amorphous eosinophilic material.¹ Primary systemic amyloidosis is associated with an underlying plasma cell dyscrasia, and unlike secondary keratinocyte-derived amyloid, it can involve internal organs. Similar to nodular amyloidosis, primary systemic amyloidosis is composed of AL proteins, and it is histologically similar to nodular amyloidosis.¹ 

Primary systemic AL amyloidosis commonly affects individuals aged 50 to 60 years. Males and females are equally affected. Macroglossia and periorbital purpura are some of the pathognomonic presentations in AL amyloidosis. The major cause of death in these patients is cardiac and renal involvement. Renal involvement commonly presents as nephrotic syndrome, and cardiac involvement can present as a restrictive cardiomyopathy with dyspnea. Other symptoms include edema, hepatosplenomegaly, bleeding diathesis, and carpal tunnel syndrome.² An evaluation for AL amyloidosis should include a complete review of systems and physical examination with studies such as complete blood cell count, comprehensive metabolic panel, serum and urine protein electrophoresis and immunofixation, and electrocardiogram. 

Cutaneous involvement in AL amyloidosis most commonly includes yellowish waxy papules, nodules, and plaques but also can include purpura and petechiae.² Bullous amyloidosis, as seen in our patient, is a rare cutaneous presentation of AL amyloidosis that usually is negative for the Nikolsky sign (Figure 2). Bullae form due to weakness in amyloid-laden dermal connective tissue.³ Eighty-eight percent of cases of bullous amyloidosis have systemic involvement.¹ Some cases have reported a familial linkage, suggesting there might be a genetic component to the disease.⁴ A PubMed search of articles indexed for MEDLINE using the terms bullous amyloidosis, bullous, amyloidosis, and amyloid revealed fewer than 35 cases of bullous amyloidosis in the English-language literature.⁵ Bullae can be located intradermally or subepidermally and commonly are hemorrhagic but also can be translucent, tender, and tense. 

A study of electron microscopy in a patient with systemic bullous amyloidosis demonstrated amyloid and keratinocyte protrusions that perforated the dermis through the spaces in the lamina densa. The study concluded that the disintegration of the lamina densa and expansion of the intercellular spaces between keratinocytes were the causes of skin fragility as well as fluid exudation.⁵ Trauma or friction to the skin are local precipitating factors for blister formation in bullous amyloidosis.  

Bullae can become apparent at any stage of AL amyloidosis, but they generally increase in size and number over time and are most common in intertriginous areas. Bullous amyloid lesions, especially those located in intertriginous areas, can have secondary impetiginization.⁶ In many cases, patients who present with bullous amyloidosis ultimately will be diagnosed with multiple myeloma or another plasma cell dyscrasia. In AL amyloidosis, only 10% to 15% of cases meet criteria for multiple myeloma, whereas 80% or more patients have a monoclonal gammopathy of undetermined significance.⁷  

The prognosis of cutaneous amyloidosis depends on the extent of organ involvement and response to treatment. Treatment is aimed at eliminating clonal plasma cell populations to decrease the production of light chains, thereby decreasing protein burden and amyloid progression. Historically, treatment options included cytotoxic chemotherapy such as oral melphalan and dexamethasone, followed by hematopoietic stem cell transplant. More recent treatment options include bortezomib, thalidomide, pomalidomide, and lenalidomide.⁸ Our patient received a regimen of bortezomib, cyclophosphamide, and dexamethasone that is used for patients with extensive multiple myeloma.  

The differential diagnosis in our patient included bullous drug eruption, which should be considered if the bullae are reoccurring at the same location and in association with the administration of a culprit drug. Bullous pemphigoid is preceded by pruritus, and biopsy demonstrates subepidermal bullae with associated eosinophilic infiltrate. Epidermolysis bullosa acquisita can present with milia and a linear pattern along the basement membrane zone with direct immunofluorescence. Traumatic purpura usually present with the classic shape and hue of an ecchymosis, and the patient will have a history of trauma. 

Cutaneous involvement of amyloidosis can be an early clue to the diagnosis of plasma cell dyscrasia. Early diagnosis and treatment can portend a better prognosis and prevent progression to renal or cardiac disease. 

To the Editor:

Erosive lichen planus (LP) often is painful, debilitating, and resistant to topical therapy making it both a diagnostic and therapeutic challenge. We report the case of an elderly woman with isolated perianal erosive LP, a rare clinical manifestation. We also review cases of erosive perianal LP reported in the literature.

A 72-year-old woman was referred to our dermatology clinic for evaluation of multiple pruritic and painful perianal lesions of 1 year’s duration. The lesions had remained stable since onset, with no other reported lesions elsewhere on body, including the mucosae. Her medical history was notable for rheumatoid arthritis, osteoporosis, hypercholesterolemia, and hypertension. She was taking methotrexate, folic acid, abatacept, alendronate, atorvastatin, and lisinopril. The patient reported she had been using abatacept for 3 years and lisinopril for 2 years. Her primary care physician initially treated the lesions as hemorrhoids but referred her to a gastroenterologist when they failed to improve. Gastroenterology evaluated the patient, and a colonoscopy was performed with unremarkable results. Thus, she was referred to dermatology for further evaluation.

Physical examination revealed 2 tender, sharply defined, angulated erosions with irregular violaceous borders involving the perianal skin (Figure 1). A biopsy of one of the lesions was taken. Histopathologic examination revealed acanthosis of the epidermis with slight compact hyperkeratosis, scattered dyskeratotic keratinocytes, and a dense bandlike lymphohistiocytic infiltrate that obliterated the dermoepidermal junction (Figure 2). A diagnosis of perianal erosive LP was made. The patient was prescribed mometasone ointment 0.1% daily with notable improvement after 2 months.

Erosive LP is an extremely rare variant of LP.¹ It typically manifests as chronic painful erosions that often can progress to scarring, ulceration, and tissue destruction. Although erosive LP most commonly involves the mucosal surfaces of the genitalia and oral mucosa, it also has been reported in the palmoplantar skin, lacrimal duct, external auditory meatus, and esophagus.^2-7 However, isolated perianal involvement is extremely rare. A PubMed search of articles indexed for MEDLINE using the terms erosive or ulcerative and lichen planus and perianal revealed 10 cases of perianal erosive LP, and weak data exist regarding therapy (Table).^8-12 Of these cases, only 3 reported isolated perianal involvement.^8-10 In most reported cases, perianal involvement manifested as extremely painful and occasionally pruritic, sharply angulated erosions and ulcers arising 0.5 to 3 cm from the anus with macerated, whitish, and violaceous borders. Most of the lesions occurred unilaterally, with only 1 case of bilateral perianal involvement.¹⁰

The differential diagnosis of perianal erosions is extensive and includes cutaneous Crohn disease, extramammary Paget disease, cutaneous malignancy, herpes simplex virus, cytomegalovirus, external hemorrhoids, lichen sclerosus, Behçet disease, lichen simplex chronicus, and drug-induced lichenoid reaction, among others. It is worth emphasizing infectious processes and cutaneous malignancies in light of our patient’s immunosuppression. Perianal cytomegalovirus has been reported in the literature in association with HIV, and it is a clinically challenging diagnosis.¹³ Cutaneous malignancy associated with the use of methotrexate also was considered in the differential diagnosis for our patient, given the increased risk for nonmelanoma skin cancer with the use of immunosuppresants.¹⁴

Along with a thorough patient history and physical examination, skin biopsy and clinicopathologic correlation are key to determine the exact etiology. Histologically, LP is characterized by a lichenoid interface dermatitis with a dense bandlike lymphohistiocytic infiltrate at the dermoepidermal junction. Other distinguishing factors include irregular acanthosis, hyperkeratosis, basal cell vacuolar degeneration, and Civatte bodies. Drug-induced LP is a possibility, but it is unclear if abatacept or lisinopril may have played a role in our patient. However, absence of eosinophils and parakeratosis suggested an idiopathic rather than drug-induced etiology. In 2016, Day et al² published a clinicopathologic review of 60 cases of perianal lichenoid dermatoses in which only 17% of lesions were LP. Of note, 90% of perianal LP lesions were of the hypertrophic variant, and none were of the erosive variant, further supporting that our case represents a rare clinical manifestation of perianal LP.

Treatment of LP varies depending on the location and subtype of the lesions and is primarily aimed at improving symptoms. Topical corticosteroids are the standard treatment of LP; however, there is limited evidence regarding their efficacy for mucosal LP. Although randomized controlled trials assessing the efficacy of different interventions on oral erosive LP are available in the literature,¹⁵ there is a paucity of studies addressing this topic for genital or perianal LP. A review of the literature regarding perianal erosive LP suggests good response to high-potency topical steroids and calcineurin inhibitors with resolution of lesions within 3 to 4 weeks.^11,15-18

Erosive LP is a painful variant that can cause erosions, ulcerations, and scarring. It rarely is seen in the perianal region alone and presents a diagnostic challenge. Treatment with high-potency topical steroid therapy seems to be effective in the few cases that have been reported as well as in our case. More comprehensive data from randomized controlled trials would be needed to evaluate their efficacy compared to other therapies.

To the Editor:

Erosive lichen planus (LP) often is painful, debilitating, and resistant to topical therapy making it both a diagnostic and therapeutic challenge. We report the case of an elderly woman with isolated perianal erosive LP, a rare clinical manifestation. We also review cases of erosive perianal LP reported in the literature.

A 72-year-old woman was referred to our dermatology clinic for evaluation of multiple pruritic and painful perianal lesions of 1 year’s duration. The lesions had remained stable since onset, with no other reported lesions elsewhere on body, including the mucosae. Her medical history was notable for rheumatoid arthritis, osteoporosis, hypercholesterolemia, and hypertension. She was taking methotrexate, folic acid, abatacept, alendronate, atorvastatin, and lisinopril. The patient reported she had been using abatacept for 3 years and lisinopril for 2 years. Her primary care physician initially treated the lesions as hemorrhoids but referred her to a gastroenterologist when they failed to improve. Gastroenterology evaluated the patient, and a colonoscopy was performed with unremarkable results. Thus, she was referred to dermatology for further evaluation.

Physical examination revealed 2 tender, sharply defined, angulated erosions with irregular violaceous borders involving the perianal skin (Figure 1). A biopsy of one of the lesions was taken. Histopathologic examination revealed acanthosis of the epidermis with slight compact hyperkeratosis, scattered dyskeratotic keratinocytes, and a dense bandlike lymphohistiocytic infiltrate that obliterated the dermoepidermal junction (Figure 2). A diagnosis of perianal erosive LP was made. The patient was prescribed mometasone ointment 0.1% daily with notable improvement after 2 months.

Erosive LP is an extremely rare variant of LP.¹ It typically manifests as chronic painful erosions that often can progress to scarring, ulceration, and tissue destruction. Although erosive LP most commonly involves the mucosal surfaces of the genitalia and oral mucosa, it also has been reported in the palmoplantar skin, lacrimal duct, external auditory meatus, and esophagus.^2-7 However, isolated perianal involvement is extremely rare. A PubMed search of articles indexed for MEDLINE using the terms erosive or ulcerative and lichen planus and perianal revealed 10 cases of perianal erosive LP, and weak data exist regarding therapy (Table).^8-12 Of these cases, only 3 reported isolated perianal involvement.^8-10 In most reported cases, perianal involvement manifested as extremely painful and occasionally pruritic, sharply angulated erosions and ulcers arising 0.5 to 3 cm from the anus with macerated, whitish, and violaceous borders. Most of the lesions occurred unilaterally, with only 1 case of bilateral perianal involvement.¹⁰

The differential diagnosis of perianal erosions is extensive and includes cutaneous Crohn disease, extramammary Paget disease, cutaneous malignancy, herpes simplex virus, cytomegalovirus, external hemorrhoids, lichen sclerosus, Behçet disease, lichen simplex chronicus, and drug-induced lichenoid reaction, among others. It is worth emphasizing infectious processes and cutaneous malignancies in light of our patient’s immunosuppression. Perianal cytomegalovirus has been reported in the literature in association with HIV, and it is a clinically challenging diagnosis.¹³ Cutaneous malignancy associated with the use of methotrexate also was considered in the differential diagnosis for our patient, given the increased risk for nonmelanoma skin cancer with the use of immunosuppresants.¹⁴

Along with a thorough patient history and physical examination, skin biopsy and clinicopathologic correlation are key to determine the exact etiology. Histologically, LP is characterized by a lichenoid interface dermatitis with a dense bandlike lymphohistiocytic infiltrate at the dermoepidermal junction. Other distinguishing factors include irregular acanthosis, hyperkeratosis, basal cell vacuolar degeneration, and Civatte bodies. Drug-induced LP is a possibility, but it is unclear if abatacept or lisinopril may have played a role in our patient. However, absence of eosinophils and parakeratosis suggested an idiopathic rather than drug-induced etiology. In 2016, Day et al² published a clinicopathologic review of 60 cases of perianal lichenoid dermatoses in which only 17% of lesions were LP. Of note, 90% of perianal LP lesions were of the hypertrophic variant, and none were of the erosive variant, further supporting that our case represents a rare clinical manifestation of perianal LP.

Treatment of LP varies depending on the location and subtype of the lesions and is primarily aimed at improving symptoms. Topical corticosteroids are the standard treatment of LP; however, there is limited evidence regarding their efficacy for mucosal LP. Although randomized controlled trials assessing the efficacy of different interventions on oral erosive LP are available in the literature,¹⁵ there is a paucity of studies addressing this topic for genital or perianal LP. A review of the literature regarding perianal erosive LP suggests good response to high-potency topical steroids and calcineurin inhibitors with resolution of lesions within 3 to 4 weeks.^11,15-18

Erosive LP is a painful variant that can cause erosions, ulcerations, and scarring. It rarely is seen in the perianal region alone and presents a diagnostic challenge. Treatment with high-potency topical steroid therapy seems to be effective in the few cases that have been reported as well as in our case. More comprehensive data from randomized controlled trials would be needed to evaluate their efficacy compared to other therapies.

To the Editor:

Erosive lichen planus (LP) often is painful, debilitating, and resistant to topical therapy making it both a diagnostic and therapeutic challenge. We report the case of an elderly woman with isolated perianal erosive LP, a rare clinical manifestation. We also review cases of erosive perianal LP reported in the literature.

A 72-year-old woman was referred to our dermatology clinic for evaluation of multiple pruritic and painful perianal lesions of 1 year’s duration. The lesions had remained stable since onset, with no other reported lesions elsewhere on body, including the mucosae. Her medical history was notable for rheumatoid arthritis, osteoporosis, hypercholesterolemia, and hypertension. She was taking methotrexate, folic acid, abatacept, alendronate, atorvastatin, and lisinopril. The patient reported she had been using abatacept for 3 years and lisinopril for 2 years. Her primary care physician initially treated the lesions as hemorrhoids but referred her to a gastroenterologist when they failed to improve. Gastroenterology evaluated the patient, and a colonoscopy was performed with unremarkable results. Thus, she was referred to dermatology for further evaluation.

Physical examination revealed 2 tender, sharply defined, angulated erosions with irregular violaceous borders involving the perianal skin (Figure 1). A biopsy of one of the lesions was taken. Histopathologic examination revealed acanthosis of the epidermis with slight compact hyperkeratosis, scattered dyskeratotic keratinocytes, and a dense bandlike lymphohistiocytic infiltrate that obliterated the dermoepidermal junction (Figure 2). A diagnosis of perianal erosive LP was made. The patient was prescribed mometasone ointment 0.1% daily with notable improvement after 2 months.

Erosive LP is an extremely rare variant of LP.¹ It typically manifests as chronic painful erosions that often can progress to scarring, ulceration, and tissue destruction. Although erosive LP most commonly involves the mucosal surfaces of the genitalia and oral mucosa, it also has been reported in the palmoplantar skin, lacrimal duct, external auditory meatus, and esophagus.^2-7 However, isolated perianal involvement is extremely rare. A PubMed search of articles indexed for MEDLINE using the terms erosive or ulcerative and lichen planus and perianal revealed 10 cases of perianal erosive LP, and weak data exist regarding therapy (Table).^8-12 Of these cases, only 3 reported isolated perianal involvement.^8-10 In most reported cases, perianal involvement manifested as extremely painful and occasionally pruritic, sharply angulated erosions and ulcers arising 0.5 to 3 cm from the anus with macerated, whitish, and violaceous borders. Most of the lesions occurred unilaterally, with only 1 case of bilateral perianal involvement.¹⁰

The differential diagnosis of perianal erosions is extensive and includes cutaneous Crohn disease, extramammary Paget disease, cutaneous malignancy, herpes simplex virus, cytomegalovirus, external hemorrhoids, lichen sclerosus, Behçet disease, lichen simplex chronicus, and drug-induced lichenoid reaction, among others. It is worth emphasizing infectious processes and cutaneous malignancies in light of our patient’s immunosuppression. Perianal cytomegalovirus has been reported in the literature in association with HIV, and it is a clinically challenging diagnosis.¹³ Cutaneous malignancy associated with the use of methotrexate also was considered in the differential diagnosis for our patient, given the increased risk for nonmelanoma skin cancer with the use of immunosuppresants.¹⁴

Along with a thorough patient history and physical examination, skin biopsy and clinicopathologic correlation are key to determine the exact etiology. Histologically, LP is characterized by a lichenoid interface dermatitis with a dense bandlike lymphohistiocytic infiltrate at the dermoepidermal junction. Other distinguishing factors include irregular acanthosis, hyperkeratosis, basal cell vacuolar degeneration, and Civatte bodies. Drug-induced LP is a possibility, but it is unclear if abatacept or lisinopril may have played a role in our patient. However, absence of eosinophils and parakeratosis suggested an idiopathic rather than drug-induced etiology. In 2016, Day et al² published a clinicopathologic review of 60 cases of perianal lichenoid dermatoses in which only 17% of lesions were LP. Of note, 90% of perianal LP lesions were of the hypertrophic variant, and none were of the erosive variant, further supporting that our case represents a rare clinical manifestation of perianal LP.

Treatment of LP varies depending on the location and subtype of the lesions and is primarily aimed at improving symptoms. Topical corticosteroids are the standard treatment of LP; however, there is limited evidence regarding their efficacy for mucosal LP. Although randomized controlled trials assessing the efficacy of different interventions on oral erosive LP are available in the literature,¹⁵ there is a paucity of studies addressing this topic for genital or perianal LP. A review of the literature regarding perianal erosive LP suggests good response to high-potency topical steroids and calcineurin inhibitors with resolution of lesions within 3 to 4 weeks.^11,15-18

Erosive LP is a painful variant that can cause erosions, ulcerations, and scarring. It rarely is seen in the perianal region alone and presents a diagnostic challenge. Treatment with high-potency topical steroid therapy seems to be effective in the few cases that have been reported as well as in our case. More comprehensive data from randomized controlled trials would be needed to evaluate their efficacy compared to other therapies.

The Diagnosis: Lichen Planus Pigmentosus-Inversus 

Histopathologic examination revealed hyperkeratosis with dense, bandlike, lymphocytic inflammation at the dermoepidermal junction with associated melanin-containing macrophages in the papillary dermis (Figure 1). The physical examination and histopathology were consistent with a diagnosis of lichen planus pigmentosus-inversus (LPPI). Treatment was discussed with the patient, with options including phototherapy, tacrolimus, or a high-dose steroid. Given that the lesions were asymptomatic and not bothersome, the patient denied treatment and agreed to routine follow-up. 

The first case of LPPI was reported in 20011; since then, approximately 100 cases have been reported in the literature.² A rare variant of lichen planus, LPPI predominantly occurs in middle-aged women.^2,3 Lichen planus pigmentosus-inversus is characterized by well-circumscribed, brown macules confined to non-sun-exposed intertriginous areas such as the axillae and groin.² Although the rash remains localized, multiple lesions could arise in the same area, such as the groin as seen in our patient (Figure 2). Unlike in lichen planus, the oral mucosa, nails, and scalp are not affected. Furthermore, pruritus typically is absent in most cases of LPPI.^2,4 Histopathologic findings include an atrophic epidermis with lichenoid infiltrates of lymphocytes and histocytes as well as substantial pigmentary incontinence with melanin-containing macrophages in the papillary dermis.^4,5 

Given the gender, age, and clinical features of our patient, this case represents a classic scenario of LPPI. It currently is unknown if ethnicity plays a role in the disorder. Lichen planus pigmentosus-inversus initially was thought to be more prevalent in White patients; however, studies have been reported in individuals with darker skin.^1,2 

The main differential diagnosis includes erythema dyschromicum perstans, postinflammatory hyperpigmentation, and lichen planus. Although erythema dyschromicum perstans develops in individuals with darker skin, lesions are restricted to the upper torso and limbs.^2-4 In both lichen planus and lichen actinicus, skin findings primarily develop in sun-exposed areas, such as the face, neck, and hands.^4,6 Given the negative history of trauma, postinflammatory hyperpigmentation was unlikely in our patient. Furthermore, a distinguishing characteristic of LPPI is the deposition of melanin deep within the dermal layer.³ 

Lesions developing in nonexposed intertriginous skin makes LPPI unique and distinguishes it from other more common conditions. The lesions commonly are hyperpigmented and are not as pruritic as other lichen-associated conditions. Lichen planus pigmentosus-inversus often persists for months, and the rash generally is resistant to treatment.^2,5 Topical tacrolimus and high-dose steroids may improve symptoms, though results have varied substantially. In addition, some cases have resolved spontaneously.^1,4,6,7 Because LPPI is asymptomatic and benign, spontaneous resolution and routine care is a reasonable treatment strategy. Some cases have supported this strategy as safe and high-value care.² 

The Diagnosis: Lichen Planus Pigmentosus-Inversus 

Histopathologic examination revealed hyperkeratosis with dense, bandlike, lymphocytic inflammation at the dermoepidermal junction with associated melanin-containing macrophages in the papillary dermis (Figure 1). The physical examination and histopathology were consistent with a diagnosis of lichen planus pigmentosus-inversus (LPPI). Treatment was discussed with the patient, with options including phototherapy, tacrolimus, or a high-dose steroid. Given that the lesions were asymptomatic and not bothersome, the patient denied treatment and agreed to routine follow-up. 

The first case of LPPI was reported in 20011; since then, approximately 100 cases have been reported in the literature.² A rare variant of lichen planus, LPPI predominantly occurs in middle-aged women.^2,3 Lichen planus pigmentosus-inversus is characterized by well-circumscribed, brown macules confined to non-sun-exposed intertriginous areas such as the axillae and groin.² Although the rash remains localized, multiple lesions could arise in the same area, such as the groin as seen in our patient (Figure 2). Unlike in lichen planus, the oral mucosa, nails, and scalp are not affected. Furthermore, pruritus typically is absent in most cases of LPPI.^2,4 Histopathologic findings include an atrophic epidermis with lichenoid infiltrates of lymphocytes and histocytes as well as substantial pigmentary incontinence with melanin-containing macrophages in the papillary dermis.^4,5 

Given the gender, age, and clinical features of our patient, this case represents a classic scenario of LPPI. It currently is unknown if ethnicity plays a role in the disorder. Lichen planus pigmentosus-inversus initially was thought to be more prevalent in White patients; however, studies have been reported in individuals with darker skin.^1,2 

The main differential diagnosis includes erythema dyschromicum perstans, postinflammatory hyperpigmentation, and lichen planus. Although erythema dyschromicum perstans develops in individuals with darker skin, lesions are restricted to the upper torso and limbs.^2-4 In both lichen planus and lichen actinicus, skin findings primarily develop in sun-exposed areas, such as the face, neck, and hands.^4,6 Given the negative history of trauma, postinflammatory hyperpigmentation was unlikely in our patient. Furthermore, a distinguishing characteristic of LPPI is the deposition of melanin deep within the dermal layer.³ 

Lesions developing in nonexposed intertriginous skin makes LPPI unique and distinguishes it from other more common conditions. The lesions commonly are hyperpigmented and are not as pruritic as other lichen-associated conditions. Lichen planus pigmentosus-inversus often persists for months, and the rash generally is resistant to treatment.^2,5 Topical tacrolimus and high-dose steroids may improve symptoms, though results have varied substantially. In addition, some cases have resolved spontaneously.^1,4,6,7 Because LPPI is asymptomatic and benign, spontaneous resolution and routine care is a reasonable treatment strategy. Some cases have supported this strategy as safe and high-value care.² 

The Diagnosis: Lichen Planus Pigmentosus-Inversus 

Histopathologic examination revealed hyperkeratosis with dense, bandlike, lymphocytic inflammation at the dermoepidermal junction with associated melanin-containing macrophages in the papillary dermis (Figure 1). The physical examination and histopathology were consistent with a diagnosis of lichen planus pigmentosus-inversus (LPPI). Treatment was discussed with the patient, with options including phototherapy, tacrolimus, or a high-dose steroid. Given that the lesions were asymptomatic and not bothersome, the patient denied treatment and agreed to routine follow-up. 

The first case of LPPI was reported in 20011; since then, approximately 100 cases have been reported in the literature.² A rare variant of lichen planus, LPPI predominantly occurs in middle-aged women.^2,3 Lichen planus pigmentosus-inversus is characterized by well-circumscribed, brown macules confined to non-sun-exposed intertriginous areas such as the axillae and groin.² Although the rash remains localized, multiple lesions could arise in the same area, such as the groin as seen in our patient (Figure 2). Unlike in lichen planus, the oral mucosa, nails, and scalp are not affected. Furthermore, pruritus typically is absent in most cases of LPPI.^2,4 Histopathologic findings include an atrophic epidermis with lichenoid infiltrates of lymphocytes and histocytes as well as substantial pigmentary incontinence with melanin-containing macrophages in the papillary dermis.^4,5 

Given the gender, age, and clinical features of our patient, this case represents a classic scenario of LPPI. It currently is unknown if ethnicity plays a role in the disorder. Lichen planus pigmentosus-inversus initially was thought to be more prevalent in White patients; however, studies have been reported in individuals with darker skin.^1,2 

The main differential diagnosis includes erythema dyschromicum perstans, postinflammatory hyperpigmentation, and lichen planus. Although erythema dyschromicum perstans develops in individuals with darker skin, lesions are restricted to the upper torso and limbs.^2-4 In both lichen planus and lichen actinicus, skin findings primarily develop in sun-exposed areas, such as the face, neck, and hands.^4,6 Given the negative history of trauma, postinflammatory hyperpigmentation was unlikely in our patient. Furthermore, a distinguishing characteristic of LPPI is the deposition of melanin deep within the dermal layer.³ 

Lesions developing in nonexposed intertriginous skin makes LPPI unique and distinguishes it from other more common conditions. The lesions commonly are hyperpigmented and are not as pruritic as other lichen-associated conditions. Lichen planus pigmentosus-inversus often persists for months, and the rash generally is resistant to treatment.^2,5 Topical tacrolimus and high-dose steroids may improve symptoms, though results have varied substantially. In addition, some cases have resolved spontaneously.^1,4,6,7 Because LPPI is asymptomatic and benign, spontaneous resolution and routine care is a reasonable treatment strategy. Some cases have supported this strategy as safe and high-value care.² 

To the Editor:

A 65-year-old man with severe atherosclerotic disease developed multiple painful eschars on the lower abdomen, thighs, sacrum, and perineum. He initially presented with myocardial ischemia and claudication and underwent 3 cardiac catheterizations as well as stenting of the superficial femoral artery. Within 2 weeks, he developed exquisitely tender nodules on the lower abdomen, clinically presumed to be sites of enoxaparin injections. These lesions gradually expanded and ulcerated to involve the sacrum, buttock, perineum, and upper thighs (Figure 1). Two punch biopsies from ulcerated skin taken 10 days apart demonstrated necrosis of skin and subcutaneous fat without evidence of vasculitis, vasculopathy, emboli, or notable inflammation despite examination of multiple levels of all submitted tissue. A definitive cause for the ulcerations remained elusive with development of new lesions. A third incisional biopsy of a newly developed, nonulcerated, subcutaneous nodule performed 8 weeks after presentation revealed multiple cholesterol emboli (Figure 2). He was treated with warfarin and clopidogrel bisulfate as well as local wound care. The lesions slowly resolved over the next 4 to 6 months.

Cholesterol embolization syndrome occurs when disrupted atherosclerotic plaques embolize from large proximal arteries to more distal arterioles, resulting in ischemic damage to 1 or more organ systems.¹ It can occur spontaneously but often is a consequence of thrombolytic therapy, anticoagulation, and angioinvasive procedures.^2,3 Cutaneous manifestations include livedo reticularis, retiform purpura, nodules, and gangrene. Although livedo reticularis may extend from the legs to the trunk, gangrenous lesions predominantly involve the distal digits.

This case illustrates the challenge in diagnosis of cholesterol emboli, both clinically and histologically. Cutaneous lesions are morphologically variable and often occur with systemic manifestations, mimicking numerous conditions.¹ Lower extremity involvement is a well-known occurrence in cholesterol embolization (ie, blue toe syndrome); however, periumbilical and lumbosacral lesions have not been emphasized in the dermatologic or peripheral vascular literature. Our patient’s initial diagnosis was enoxaparin necrosis at abdominal injection sites; however, this unusual distribution of lesions was ultimately determined to be the consequence of cholesterol embolization from the inferior epigastric and superficial external pudendal arteries at the time of stenting of the superficial femoral artery. Proximal truncal involvement should be recognized as an atypical but important cutaneous manifestation to facilitate timely diagnosis and treatment.^4,5

Our patient’s course also highlights the potential need for multiple biopsies. Although the gold standard for diagnosis is histologic confirmation, a negative biopsy does not always exclude cholesterol emboli, and one should have a low threshold to perform additional biopsies in the appropriate clinical setting.

To the Editor:

A 65-year-old man with severe atherosclerotic disease developed multiple painful eschars on the lower abdomen, thighs, sacrum, and perineum. He initially presented with myocardial ischemia and claudication and underwent 3 cardiac catheterizations as well as stenting of the superficial femoral artery. Within 2 weeks, he developed exquisitely tender nodules on the lower abdomen, clinically presumed to be sites of enoxaparin injections. These lesions gradually expanded and ulcerated to involve the sacrum, buttock, perineum, and upper thighs (Figure 1). Two punch biopsies from ulcerated skin taken 10 days apart demonstrated necrosis of skin and subcutaneous fat without evidence of vasculitis, vasculopathy, emboli, or notable inflammation despite examination of multiple levels of all submitted tissue. A definitive cause for the ulcerations remained elusive with development of new lesions. A third incisional biopsy of a newly developed, nonulcerated, subcutaneous nodule performed 8 weeks after presentation revealed multiple cholesterol emboli (Figure 2). He was treated with warfarin and clopidogrel bisulfate as well as local wound care. The lesions slowly resolved over the next 4 to 6 months.

Cholesterol embolization syndrome occurs when disrupted atherosclerotic plaques embolize from large proximal arteries to more distal arterioles, resulting in ischemic damage to 1 or more organ systems.¹ It can occur spontaneously but often is a consequence of thrombolytic therapy, anticoagulation, and angioinvasive procedures.^2,3 Cutaneous manifestations include livedo reticularis, retiform purpura, nodules, and gangrene. Although livedo reticularis may extend from the legs to the trunk, gangrenous lesions predominantly involve the distal digits.

This case illustrates the challenge in diagnosis of cholesterol emboli, both clinically and histologically. Cutaneous lesions are morphologically variable and often occur with systemic manifestations, mimicking numerous conditions.¹ Lower extremity involvement is a well-known occurrence in cholesterol embolization (ie, blue toe syndrome); however, periumbilical and lumbosacral lesions have not been emphasized in the dermatologic or peripheral vascular literature. Our patient’s initial diagnosis was enoxaparin necrosis at abdominal injection sites; however, this unusual distribution of lesions was ultimately determined to be the consequence of cholesterol embolization from the inferior epigastric and superficial external pudendal arteries at the time of stenting of the superficial femoral artery. Proximal truncal involvement should be recognized as an atypical but important cutaneous manifestation to facilitate timely diagnosis and treatment.^4,5

Our patient’s course also highlights the potential need for multiple biopsies. Although the gold standard for diagnosis is histologic confirmation, a negative biopsy does not always exclude cholesterol emboli, and one should have a low threshold to perform additional biopsies in the appropriate clinical setting.

To the Editor:

A 65-year-old man with severe atherosclerotic disease developed multiple painful eschars on the lower abdomen, thighs, sacrum, and perineum. He initially presented with myocardial ischemia and claudication and underwent 3 cardiac catheterizations as well as stenting of the superficial femoral artery. Within 2 weeks, he developed exquisitely tender nodules on the lower abdomen, clinically presumed to be sites of enoxaparin injections. These lesions gradually expanded and ulcerated to involve the sacrum, buttock, perineum, and upper thighs (Figure 1). Two punch biopsies from ulcerated skin taken 10 days apart demonstrated necrosis of skin and subcutaneous fat without evidence of vasculitis, vasculopathy, emboli, or notable inflammation despite examination of multiple levels of all submitted tissue. A definitive cause for the ulcerations remained elusive with development of new lesions. A third incisional biopsy of a newly developed, nonulcerated, subcutaneous nodule performed 8 weeks after presentation revealed multiple cholesterol emboli (Figure 2). He was treated with warfarin and clopidogrel bisulfate as well as local wound care. The lesions slowly resolved over the next 4 to 6 months.

Cholesterol embolization syndrome occurs when disrupted atherosclerotic plaques embolize from large proximal arteries to more distal arterioles, resulting in ischemic damage to 1 or more organ systems.¹ It can occur spontaneously but often is a consequence of thrombolytic therapy, anticoagulation, and angioinvasive procedures.^2,3 Cutaneous manifestations include livedo reticularis, retiform purpura, nodules, and gangrene. Although livedo reticularis may extend from the legs to the trunk, gangrenous lesions predominantly involve the distal digits.

This case illustrates the challenge in diagnosis of cholesterol emboli, both clinically and histologically. Cutaneous lesions are morphologically variable and often occur with systemic manifestations, mimicking numerous conditions.¹ Lower extremity involvement is a well-known occurrence in cholesterol embolization (ie, blue toe syndrome); however, periumbilical and lumbosacral lesions have not been emphasized in the dermatologic or peripheral vascular literature. Our patient’s initial diagnosis was enoxaparin necrosis at abdominal injection sites; however, this unusual distribution of lesions was ultimately determined to be the consequence of cholesterol embolization from the inferior epigastric and superficial external pudendal arteries at the time of stenting of the superficial femoral artery. Proximal truncal involvement should be recognized as an atypical but important cutaneous manifestation to facilitate timely diagnosis and treatment.^4,5

Our patient’s course also highlights the potential need for multiple biopsies. Although the gold standard for diagnosis is histologic confirmation, a negative biopsy does not always exclude cholesterol emboli, and one should have a low threshold to perform additional biopsies in the appropriate clinical setting.

The Diagnosis: Cutaneous Collagenous Vasculopathy 

Cutaneous collagenous vasculopathy (CCV) is an idiopathic microangiopathy of the small vessels in the superficial dermis. A condition first identified by Salama and Rosenthal¹ in 2000, CCV likely is underreported, as its clinical mimickers are not routinely biopsied.² It presents as asymptomatic telangiectatic macules, initially on the lower extremities and often spreading to the trunk. Cutaneous collagenous vasculopathy often is seen in middle-aged adults, and most patients have comorbidities such as hypertension, diabetes mellitus, or cardiovascular disease. The exact etiology of this disease is unknown.^3,4 

Histopathologically, CCV is characterized by dilated superficial vessels with thickened eosinophilic walls. The eosinophilic material is composed of hyalinized type IV collagen, which is periodic acid-Schiff positive and diastase resistant (Figure 1).^3,4 Stains for amyloid are negative.  

Generalized essential telangiectasia (GET) is a condition that presents with symmetric, blanchable, erythematous telangiectases.⁵ These lesions can occur alone or can accompany systemic diseases. Similar to CCV, the telangiectases tend to begin on the legs before gradually spreading to the trunk; however, this process more often is seen in females and occurs at an earlier age. Unlike CCV, GET can occur on mucosal surfaces, with cases of conjunctival and oral involvement reported.⁶ Generalized essential telangiectasia usually is a diagnosis of exclusion.^7,8 It is thought that many CCV lesions have been misclassified clinically as GET, which highlights the importance of biopsy. Microscopically, GET is distinct from CCV in that the superficial dermis lacks thick-walled vessels.^5,7 Although usually not associated with systemic diseases or progressive morbidity, treatment options are limited.⁸ 

Livedoid vasculopathy, also known as atrophie blanche, is caused by fibrin thrombi occlusion of dermal vessels. Clinically, patients have recurrent telangiectatic papules and painful ulcers on the lower extremities that gradually heal, leaving behind white stellate scars. It is caused by an underlying prothrombotic state with a superimposed inflammatory response.⁹ Livedoid vasculopathy primarily affects middle-aged women, and many patients have comorbidities such as scleroderma or systemic lupus erythematosus. Histologically, the epidermis often is ulcerated, and thrombi are visualized within small vessels. Eosinophilic fibrinoid material is deposited in vessel walls, including but not confined to vessels at the base of the epidermal ulcer (Figure 2). The fibrinoid material is periodic acid-Schiff positive and diastase resistant and can be highlighted with immunofluorescence, which may help to distinguish this entity from CCV.^1,9 As the disease progresses, vessels are diffusely hyalinized, and there is epidermal atrophy and dermal sclerosis. Treatment options include antiplatelet and fibrinolytic drugs with a multidisciplinary approach to resolve pain and scarring.⁹ 

Primary systemic amyloidosis is a rare condition, and cutaneous manifestations are seen in approximately one-third of affected individuals. Amyloid deposition results in waxy papules that predominantly affect the face and periorbital areas but also may occur on the neck, flexural areas, and genitalia.⁵ Because the amyloid deposits also can be found within vessel walls, hemorrhagic lesions may occur. Microscopically, amorphous eosinophilic material can be found within the vessel walls, similar to CCV (Figure 3A); however, when stained with Congo red, cutaneous amyloidosis shows waxy red-orange material involving the vessel walls and exhibits apple green birefringence under polarization (Figure 3B).¹⁰ Amyloid also will be negative for type IV collagen, fibronectin, and laminin, whereas CCV will be positive.⁵

 Stasis dermatitis is a result of chronic venous insufficiency and causes characteristic clinical and histopathologic findings. In contrast to CCV, where hyalinized type IV collagen is deposited within the vessel wall, plasma and fibrin are deposited around the walls of capillaries in stasis dermatitis.¹¹ Additional microscopic findings of stasis dermatitis include superficial dermal angioplasia, hemorrhage, and hemosiderin deposition (Figure 4).  

The Diagnosis: Cutaneous Collagenous Vasculopathy 

Cutaneous collagenous vasculopathy (CCV) is an idiopathic microangiopathy of the small vessels in the superficial dermis. A condition first identified by Salama and Rosenthal¹ in 2000, CCV likely is underreported, as its clinical mimickers are not routinely biopsied.² It presents as asymptomatic telangiectatic macules, initially on the lower extremities and often spreading to the trunk. Cutaneous collagenous vasculopathy often is seen in middle-aged adults, and most patients have comorbidities such as hypertension, diabetes mellitus, or cardiovascular disease. The exact etiology of this disease is unknown.^3,4 

Histopathologically, CCV is characterized by dilated superficial vessels with thickened eosinophilic walls. The eosinophilic material is composed of hyalinized type IV collagen, which is periodic acid-Schiff positive and diastase resistant (Figure 1).^3,4 Stains for amyloid are negative.  

Generalized essential telangiectasia (GET) is a condition that presents with symmetric, blanchable, erythematous telangiectases.⁵ These lesions can occur alone or can accompany systemic diseases. Similar to CCV, the telangiectases tend to begin on the legs before gradually spreading to the trunk; however, this process more often is seen in females and occurs at an earlier age. Unlike CCV, GET can occur on mucosal surfaces, with cases of conjunctival and oral involvement reported.⁶ Generalized essential telangiectasia usually is a diagnosis of exclusion.^7,8 It is thought that many CCV lesions have been misclassified clinically as GET, which highlights the importance of biopsy. Microscopically, GET is distinct from CCV in that the superficial dermis lacks thick-walled vessels.^5,7 Although usually not associated with systemic diseases or progressive morbidity, treatment options are limited.⁸ 

Livedoid vasculopathy, also known as atrophie blanche, is caused by fibrin thrombi occlusion of dermal vessels. Clinically, patients have recurrent telangiectatic papules and painful ulcers on the lower extremities that gradually heal, leaving behind white stellate scars. It is caused by an underlying prothrombotic state with a superimposed inflammatory response.⁹ Livedoid vasculopathy primarily affects middle-aged women, and many patients have comorbidities such as scleroderma or systemic lupus erythematosus. Histologically, the epidermis often is ulcerated, and thrombi are visualized within small vessels. Eosinophilic fibrinoid material is deposited in vessel walls, including but not confined to vessels at the base of the epidermal ulcer (Figure 2). The fibrinoid material is periodic acid-Schiff positive and diastase resistant and can be highlighted with immunofluorescence, which may help to distinguish this entity from CCV.^1,9 As the disease progresses, vessels are diffusely hyalinized, and there is epidermal atrophy and dermal sclerosis. Treatment options include antiplatelet and fibrinolytic drugs with a multidisciplinary approach to resolve pain and scarring.⁹ 

Primary systemic amyloidosis is a rare condition, and cutaneous manifestations are seen in approximately one-third of affected individuals. Amyloid deposition results in waxy papules that predominantly affect the face and periorbital areas but also may occur on the neck, flexural areas, and genitalia.⁵ Because the amyloid deposits also can be found within vessel walls, hemorrhagic lesions may occur. Microscopically, amorphous eosinophilic material can be found within the vessel walls, similar to CCV (Figure 3A); however, when stained with Congo red, cutaneous amyloidosis shows waxy red-orange material involving the vessel walls and exhibits apple green birefringence under polarization (Figure 3B).¹⁰ Amyloid also will be negative for type IV collagen, fibronectin, and laminin, whereas CCV will be positive.⁵

 Stasis dermatitis is a result of chronic venous insufficiency and causes characteristic clinical and histopathologic findings. In contrast to CCV, where hyalinized type IV collagen is deposited within the vessel wall, plasma and fibrin are deposited around the walls of capillaries in stasis dermatitis.¹¹ Additional microscopic findings of stasis dermatitis include superficial dermal angioplasia, hemorrhage, and hemosiderin deposition (Figure 4).  

The Diagnosis: Cutaneous Collagenous Vasculopathy 

Cutaneous collagenous vasculopathy (CCV) is an idiopathic microangiopathy of the small vessels in the superficial dermis. A condition first identified by Salama and Rosenthal¹ in 2000, CCV likely is underreported, as its clinical mimickers are not routinely biopsied.² It presents as asymptomatic telangiectatic macules, initially on the lower extremities and often spreading to the trunk. Cutaneous collagenous vasculopathy often is seen in middle-aged adults, and most patients have comorbidities such as hypertension, diabetes mellitus, or cardiovascular disease. The exact etiology of this disease is unknown.^3,4 

Histopathologically, CCV is characterized by dilated superficial vessels with thickened eosinophilic walls. The eosinophilic material is composed of hyalinized type IV collagen, which is periodic acid-Schiff positive and diastase resistant (Figure 1).^3,4 Stains for amyloid are negative.  

Generalized essential telangiectasia (GET) is a condition that presents with symmetric, blanchable, erythematous telangiectases.⁵ These lesions can occur alone or can accompany systemic diseases. Similar to CCV, the telangiectases tend to begin on the legs before gradually spreading to the trunk; however, this process more often is seen in females and occurs at an earlier age. Unlike CCV, GET can occur on mucosal surfaces, with cases of conjunctival and oral involvement reported.⁶ Generalized essential telangiectasia usually is a diagnosis of exclusion.^7,8 It is thought that many CCV lesions have been misclassified clinically as GET, which highlights the importance of biopsy. Microscopically, GET is distinct from CCV in that the superficial dermis lacks thick-walled vessels.^5,7 Although usually not associated with systemic diseases or progressive morbidity, treatment options are limited.⁸ 

Livedoid vasculopathy, also known as atrophie blanche, is caused by fibrin thrombi occlusion of dermal vessels. Clinically, patients have recurrent telangiectatic papules and painful ulcers on the lower extremities that gradually heal, leaving behind white stellate scars. It is caused by an underlying prothrombotic state with a superimposed inflammatory response.⁹ Livedoid vasculopathy primarily affects middle-aged women, and many patients have comorbidities such as scleroderma or systemic lupus erythematosus. Histologically, the epidermis often is ulcerated, and thrombi are visualized within small vessels. Eosinophilic fibrinoid material is deposited in vessel walls, including but not confined to vessels at the base of the epidermal ulcer (Figure 2). The fibrinoid material is periodic acid-Schiff positive and diastase resistant and can be highlighted with immunofluorescence, which may help to distinguish this entity from CCV.^1,9 As the disease progresses, vessels are diffusely hyalinized, and there is epidermal atrophy and dermal sclerosis. Treatment options include antiplatelet and fibrinolytic drugs with a multidisciplinary approach to resolve pain and scarring.⁹ 

Primary systemic amyloidosis is a rare condition, and cutaneous manifestations are seen in approximately one-third of affected individuals. Amyloid deposition results in waxy papules that predominantly affect the face and periorbital areas but also may occur on the neck, flexural areas, and genitalia.⁵ Because the amyloid deposits also can be found within vessel walls, hemorrhagic lesions may occur. Microscopically, amorphous eosinophilic material can be found within the vessel walls, similar to CCV (Figure 3A); however, when stained with Congo red, cutaneous amyloidosis shows waxy red-orange material involving the vessel walls and exhibits apple green birefringence under polarization (Figure 3B).¹⁰ Amyloid also will be negative for type IV collagen, fibronectin, and laminin, whereas CCV will be positive.⁵

 Stasis dermatitis is a result of chronic venous insufficiency and causes characteristic clinical and histopathologic findings. In contrast to CCV, where hyalinized type IV collagen is deposited within the vessel wall, plasma and fibrin are deposited around the walls of capillaries in stasis dermatitis.¹¹ Additional microscopic findings of stasis dermatitis include superficial dermal angioplasia, hemorrhage, and hemosiderin deposition (Figure 4).  

In 2019, the   2 Current Procedural Terminology (CPT) codes for skin biopsies (11100 and 11101) were replaced with 6 new CPT codes that   specify biopsy technique   and associated procedural complexity. ^1,2 Prior to the coding changes, all biopsies were reimbursed at the same payment level, but a punch biopsy (11104; national nonfacility Medicare payment, $133.29) is now reimbursed more than a shave biopsy (11102; national nonfacility Medicare payment, $106.42). ³ We sought to evaluate whether the decrease in reimbursement for shave biopsies and concurrent increase in reimbursement for punch biopsies led to a shift from shave to punch biopsy utilization.

Methods

We examined shave and punch biopsies submitted for pathologic examination at Brigham and Women’s Hospital, Massachusetts General Hospital, and Massachusetts General Physician’s Organization (all in Boston, Massachusetts), and Penn Medicine, University of Pennsylvania Health System (Philadelphia, Pennsylvania), in May 2018 vs May 2019 (four months after new codes were implemented). This study was approved by Partners HealthCare (Boston, Massachusetts) and the University of Pennsylvania institutional review boards.

We included shave and punch biopsies of skin performed by physician dermatologists and mid-level providers (ie, physician assistants, nurse practitioners) at dermatology practices. All biopsies performed by a technique other than shave or punch, unspecified biopsy type, consultation cases, nonskin biopsies (eg, mucosa), and biopsies performed at nondermatology practices were excluded. We also excluded biopsies by providers who were not present during both study periods to account for provider mix.

Statistical Analysis
To evaluate for changes in the ratio of shave to punch biopsy utilization over time, we performed χ² tests. Because care practices may differ between private and academic settings as well as between physicians and mid-level providers, we performed subgroup analyses by practice setting and provider type.⁴

Results

We identified 11,785 biopsies (12.11% of which were punch) submitted for pathologic examination in May 2018 compared to 11,291 biopsies (12.08% of which were punch) in May 2019 (Table). The overall use of punch biopsies relative to shave biopsies did not change between the years. There was a relative decrease in punch biopsy use among academic practices (−1.88%; P=.032) and a relative increase in punch biopsy use among private practices (+0.90%; P=.043). Provider type was not associated with differing utilization of biopsy type.

Comment

Overall, there was not a considerable shift in utilization behavior from shave to punch biopsies after the introduction of new coding changes. However, our study does demonstrate a small yet significant increase in punch biopsy utilization among private practices, and a decrease among academic practices. Although the change in biopsy utilization behavior is small in magnitude, it may have a substantial impact when extrapolated to behavior across the entire United States.

We were unable to assess additional factors, such as clinical diagnosis, body site, and cosmetic concerns, that may impact biopsy type selection in this study. Although we included multiple study sites to improve generalizability, our findings may not be representative of all biopsies performed in the dermatology setting. The baseline difference in relative punch biopsy use in academic vs private practices may reflect differences in patient populations and chief concerns, but assuming these features are stable over a 1-year time period, our findings should remain valid. Future studies should focus on qualitative evaluations of physician decision-making and evaluate whether similar trends persist over time.

Conclusion

Skin biopsy utilization trends among differing practice and provider types should continue to be monitored to assess for longitudinal trends in utilization within the context of updated billing codes and associated reimbursements.

In 2019, the   2 Current Procedural Terminology (CPT) codes for skin biopsies (11100 and 11101) were replaced with 6 new CPT codes that   specify biopsy technique   and associated procedural complexity. ^1,2 Prior to the coding changes, all biopsies were reimbursed at the same payment level, but a punch biopsy (11104; national nonfacility Medicare payment, $133.29) is now reimbursed more than a shave biopsy (11102; national nonfacility Medicare payment, $106.42). ³ We sought to evaluate whether the decrease in reimbursement for shave biopsies and concurrent increase in reimbursement for punch biopsies led to a shift from shave to punch biopsy utilization.

Methods

We examined shave and punch biopsies submitted for pathologic examination at Brigham and Women’s Hospital, Massachusetts General Hospital, and Massachusetts General Physician’s Organization (all in Boston, Massachusetts), and Penn Medicine, University of Pennsylvania Health System (Philadelphia, Pennsylvania), in May 2018 vs May 2019 (four months after new codes were implemented). This study was approved by Partners HealthCare (Boston, Massachusetts) and the University of Pennsylvania institutional review boards.

We included shave and punch biopsies of skin performed by physician dermatologists and mid-level providers (ie, physician assistants, nurse practitioners) at dermatology practices. All biopsies performed by a technique other than shave or punch, unspecified biopsy type, consultation cases, nonskin biopsies (eg, mucosa), and biopsies performed at nondermatology practices were excluded. We also excluded biopsies by providers who were not present during both study periods to account for provider mix.

Statistical Analysis
To evaluate for changes in the ratio of shave to punch biopsy utilization over time, we performed χ² tests. Because care practices may differ between private and academic settings as well as between physicians and mid-level providers, we performed subgroup analyses by practice setting and provider type.⁴

Results

We identified 11,785 biopsies (12.11% of which were punch) submitted for pathologic examination in May 2018 compared to 11,291 biopsies (12.08% of which were punch) in May 2019 (Table). The overall use of punch biopsies relative to shave biopsies did not change between the years. There was a relative decrease in punch biopsy use among academic practices (−1.88%; P=.032) and a relative increase in punch biopsy use among private practices (+0.90%; P=.043). Provider type was not associated with differing utilization of biopsy type.

Comment

Overall, there was not a considerable shift in utilization behavior from shave to punch biopsies after the introduction of new coding changes. However, our study does demonstrate a small yet significant increase in punch biopsy utilization among private practices, and a decrease among academic practices. Although the change in biopsy utilization behavior is small in magnitude, it may have a substantial impact when extrapolated to behavior across the entire United States.

We were unable to assess additional factors, such as clinical diagnosis, body site, and cosmetic concerns, that may impact biopsy type selection in this study. Although we included multiple study sites to improve generalizability, our findings may not be representative of all biopsies performed in the dermatology setting. The baseline difference in relative punch biopsy use in academic vs private practices may reflect differences in patient populations and chief concerns, but assuming these features are stable over a 1-year time period, our findings should remain valid. Future studies should focus on qualitative evaluations of physician decision-making and evaluate whether similar trends persist over time.

Conclusion

Skin biopsy utilization trends among differing practice and provider types should continue to be monitored to assess for longitudinal trends in utilization within the context of updated billing codes and associated reimbursements.

In 2019, the   2 Current Procedural Terminology (CPT) codes for skin biopsies (11100 and 11101) were replaced with 6 new CPT codes that   specify biopsy technique   and associated procedural complexity. ^1,2 Prior to the coding changes, all biopsies were reimbursed at the same payment level, but a punch biopsy (11104; national nonfacility Medicare payment, $133.29) is now reimbursed more than a shave biopsy (11102; national nonfacility Medicare payment, $106.42). ³ We sought to evaluate whether the decrease in reimbursement for shave biopsies and concurrent increase in reimbursement for punch biopsies led to a shift from shave to punch biopsy utilization.

Methods

We examined shave and punch biopsies submitted for pathologic examination at Brigham and Women’s Hospital, Massachusetts General Hospital, and Massachusetts General Physician’s Organization (all in Boston, Massachusetts), and Penn Medicine, University of Pennsylvania Health System (Philadelphia, Pennsylvania), in May 2018 vs May 2019 (four months after new codes were implemented). This study was approved by Partners HealthCare (Boston, Massachusetts) and the University of Pennsylvania institutional review boards.

We included shave and punch biopsies of skin performed by physician dermatologists and mid-level providers (ie, physician assistants, nurse practitioners) at dermatology practices. All biopsies performed by a technique other than shave or punch, unspecified biopsy type, consultation cases, nonskin biopsies (eg, mucosa), and biopsies performed at nondermatology practices were excluded. We also excluded biopsies by providers who were not present during both study periods to account for provider mix.

Statistical Analysis
To evaluate for changes in the ratio of shave to punch biopsy utilization over time, we performed χ² tests. Because care practices may differ between private and academic settings as well as between physicians and mid-level providers, we performed subgroup analyses by practice setting and provider type.⁴

Results

We identified 11,785 biopsies (12.11% of which were punch) submitted for pathologic examination in May 2018 compared to 11,291 biopsies (12.08% of which were punch) in May 2019 (Table). The overall use of punch biopsies relative to shave biopsies did not change between the years. There was a relative decrease in punch biopsy use among academic practices (−1.88%; P=.032) and a relative increase in punch biopsy use among private practices (+0.90%; P=.043). Provider type was not associated with differing utilization of biopsy type.

Comment

Overall, there was not a considerable shift in utilization behavior from shave to punch biopsies after the introduction of new coding changes. However, our study does demonstrate a small yet significant increase in punch biopsy utilization among private practices, and a decrease among academic practices. Although the change in biopsy utilization behavior is small in magnitude, it may have a substantial impact when extrapolated to behavior across the entire United States.

We were unable to assess additional factors, such as clinical diagnosis, body site, and cosmetic concerns, that may impact biopsy type selection in this study. Although we included multiple study sites to improve generalizability, our findings may not be representative of all biopsies performed in the dermatology setting. The baseline difference in relative punch biopsy use in academic vs private practices may reflect differences in patient populations and chief concerns, but assuming these features are stable over a 1-year time period, our findings should remain valid. Future studies should focus on qualitative evaluations of physician decision-making and evaluate whether similar trends persist over time.

Conclusion

Skin biopsy utilization trends among differing practice and provider types should continue to be monitored to assess for longitudinal trends in utilization within the context of updated billing codes and associated reimbursements.