Histiocytoid melanoma: Diagnostic pitfall and mimicker of non-Langerhans cell histiocytoses including reticulohistiocytoma.

Melanoma and benign histiocytic proliferations can sometimes show considerable clinical and histopathologic overlap. Recently, cases of melanomas resembling xanthogranuloma and Rosai-Dorfman disease have been reported, and herein we report a case of melanoma closely mimicking reticulohistiocytoma. An 84-year-old man presented with a 1 cm purple-red nodule on his arm concerning for squamous cell carcinoma. While the biopsy findings resembled reticulohistiocytoma, the clinical context and regression changes at the lesion perimeter raised stronger concern for melanoma, which was confirmed with immunohistochemistry. We review prior rare reports of melanomas resembling non-Langerhans cell histiocytic proliferations and summarize helpful clinical and histopathologic clues to avoid a diagnostic pitfall when confronted with this unusual quandary.

Kikuchi-Fujimoto disease preceded by lupus erythematosus panniculitis: do these findings together herald the onset of systemic lupus erythematosus?

Kikuchi-Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, is a rare disorder that must be distinguished from systemic lupus erythematosus (SLE). Although a minority of patients with KFD develop SLE, most patients have a self-limited disease. Importantly, KFD can have skin manifestations resembling cutaneous lupus. Therefore, the diagnosis of SLE should be predicated on a complete rheumatologic workup and not on the constellation of skin disease and lymphadenitis. Nonetheless, as our exceedingly rare case illustrates, patients who do not initially meet diagnostic criteria for SLE require dermatologic follow-up. We present a young adult woman who had a remote history of KFD and later presented with combined features of discoid lupus and lupus erythematosus panniculitis (LEP). On subsequent rheumatologic workup, she fulfilled criteria for SLE. We discuss the differential diagnosis of both KFD and LEP and emphasize how strong communication among dermatologists and other healthcare providers is essential in the management of patients with KFD.

Concordance Analysis of the 23-Gene Expression Signature (myPath Melanoma) With Fluorescence In Situ Hybridization Assay and Single Nucleotide Polymorphism Array in the Analysis of Challenging Melanocytic Lesions: Results From an Academic Medical Center.

BACKGROUND: Fluorescence in situ hybridization (FISH) and single nucleotide polymorphism (SNP) arrays are well-established molecular tests for the analysis of challenging melanocytic lesions. A 23-gene expression signature (GES), marketed as myPath Melanoma, is a recently introduced molecular test that categorizes melanocytic lesions as "benign," "malignant," and "indeterminate." There are few studies on the concordance between FISH, SNP, and GES in the analysis of melanocytic lesions. METHODS: A single-institution retrospective analysis of 61 contiguous cases of challenging melanocytic lesions with molecular analysis by 2 or more techniques. The primary objective was to determine the intertest agreement, which was calculated as percent agreement. A secondary objective was to determine the combined-test performance, that is, the frequency of obtaining a successful test (a test with an abnormal or normal, benign or malignant result) when 2 or more molecular tests were performed. RESULTS: Of the 61 cases, 58 cases were submitted for analysis using the GES assay, 44 cases were submitted for FISH analysis, and 21 cases were submitted for SNP array analysis. Percent agreement between GES and FISH array was 50.9% (18/34), which improved to 69.7% (18/23) when indeterminate/equivocal results were excluded. Similarly, percent agreement between GES and SNP array was 57.1% (8/14); this improved to 77.8% (7/9) when indeterminate/equivocal results were excluded. In 44% of cases submitted for GES and FISH and in 39% of cases submitted for GES and SNP, one test was successful and the other was not. CONCLUSION: For challenging melanocytic lesions, the choice of a molecular test is consequential as the GES assay correlated with FISH and SNP arrays approximately only half of the time. This improved when cases with indeterminate/equivocal results were excluded from the calculations. The combined-test analysis supports the utility of conducting more than one molecular test, as this increased the odds of obtaining a successful test.

Risk of melanoma following keratinocyte malignancies.

Patients diagnosed with keratinocyte cancer experience heightened risk for melanoma, yet patients who go on to develop this malignancy have not been well-characterized. We followed a population-based cohort of 2243 participants with histologically confirmed KC identified from dermatology and pathology practices who did not have a history of internal malignancy (1363 BCC, 880 SCC). A total of 77 participants went on to develop melanoma. Individual-level data were collected via personal interviews including demographic information and skin cancer risk factors, as well as KC tumor characteristics such as anatomic site and histologic subtype. Using adjusted Cox proportionate hazards models, older patients (age 61 or older vs 60 or younger) were at twofold increased risk for developing melanoma following KC (age 61-65 HR = 2.5; 95% CI = 1.3-4.6) (age > 65 HR = 2.0; 95% CI = 1.2-3.4) and women were at reduced risk compared to men (HR = 0.5; 95% CI = 0.3-0.8). Among patients with BCC, those with tumors on the trunk/limbs compared to the head/neck were at greater risk for subsequent melanoma (HR = 2.7; 95% CI = 1.3-5.7). Subsequent risk of melanoma also related to established risk factors including blond/red vs dark hair (HR = 1.9; 95% CI = 1.1-3.4), tendency to burn rather than tan (HR = 1.7; 95% CI = 1.0-2.7), ≥1 nevi on their back compared to no nevi (HR = 2.2; 95% CI = 1.2-3.8) and a history of ≥1 painful childhood sunburns vs none (HR = 2.1; 95% CI = 1.2-3.6). Thus, in addition to pigmentary traits, ultraviolet radiation (UVR)-related factors and clinical features of KC such as anatomic site may be useful in identifying patients at increased risk for melanoma after KC.

Cutaneous crospovidone reaction secondary to subcutaneous injection of buprenorphine.

Crospovidone is an insoluble pharmaceutical disintegrant that has been implicated in a rare foreign body reaction in injection drug users, classically associated with pulmonary angiothrombosis. We recently reported the first known cases of cutaneous crospovidone deposition. We herein report two additional cases with unique clinicopathologic manifestations, both in the setting of suspected injection drug abuse. Additionally, we provide a comprehensive overview of the distinct histomorphology and reproducible histochemistry of crospovidone.

Small and Isolated Immunohistochemistry-positive Cells in Melanoma Sentinel Lymph Nodes Are Associated With Disease-specific and Recurrence-free Survival Comparable to that of Sentinel Lymph Nodes Negative for Melanoma.

Although immunohistochemistry (IHC) has improved our ability to detect melanoma metastases in sentinel lymph nodes (SLN), the American Joint Committee on Cancer (AJCC) does not provide a lower threshold for determining if a SLN is positive for metastasis. Existing literature suggests that even a small aggregate or an enlarged, abnormal cell detectable by IHC can be associated with an adverse outcome. In our experience, however, some SLNs contain small solitary cells the size of neighboring lymphocytes demonstrable only by IHC. We sought to determine their clinical significance. A total of 821 patients underwent a SLN biopsy at our institution over a 12-year period. In all, 639 (77.8%) were SLN-negative, 125 (15.2%) were SLN-positive, and 57 (6.9%) had rare IHC-positive cells of undetermined clinical significance with no disease progression over a mean 59-month follow-up. Kaplan-Meier method with pair-wise comparisons revealed no significant difference in disease-specific survival and recurrence-free survival between SLN-negative and rare IHC-positive groups. There were significant differences in survival and recurrence between patients in the rare IHC-positive group and those with melanoma metastases, including those with solitary melanoma cells and those with tumor burdens ≤0.2 mm. While the lower diagnostic threshold for metastatic melanoma on IHC-stained sections needs to be studied further, our data suggest that rare IHC-positive cells lacking cytomorphologic features of overt malignancy are equivocal for melanoma and could impart a similar prognosis as patients with no evidence of SLN involvement.

Spontaneous Hair Repigmentation in an 80-Year-Old Man: A Case of Melanoma-Associated Hair Repigmentation and Review of the Literature.

Spontaneous hair repigmentation of physiologically white or gray hair is a rare occurrence that may be associated with melanoma in elderly individuals. We present the first case of this phenomenon in a man. A gray-haired, 80-year-old man presented to dermatology clinic with a 3-cm lock of black hair on his vertex scalp that developed over 1 year. Punch biopsies showed an increase in junctional dendritic melanocytes with rare pagetoid cells and extension along the follicular outer root sheath epithelium and interfollicular epidermis, associated with prominent dendritic melanocytic hyperplasia and pigment-containing melanocytes within the hair bulbs. Although the findings on the biopsies were not diagnostic of melanoma in situ, an irregular interfollicular distribution of melanocytes was concerning for an adjacent atypical process. A complete excision was performed and revealed melanoma in situ, lentigo maligna type. Rare reports describe spontaneous hair repigmentation as a harbinger of lentigo maligna in women. Repigmentation can occur in the setting of proliferation of malignant pigment-producing melanocytes or by paracrine stimulation of benign bulbar melanocytes through receptor tyrosine kinase KIT activation. Presence of prominent dendritic melanocytic hyperplasia and pigment-containing melanocytes within the hair bulbs in our patient's biopsies was suggestive of paracrine or physiologic stimulation of bulbar melanocytes. Given the importance of early melanoma detection and the low visibility of the scalp, this report raises awareness of an extraordinary presentation of lentigo maligna and exemplifies the importance of close clinicopathologic correlation to ensure optimal clinical management and patient outcome.

A diagnostically-challenging case of melanoma ex blue nevus with comprehensive molecular analysis, including the 23-gene expression signature (myPath melanoma).

Melanoma ex blue nevus (MEBN) is a rare, aggressive, and potentially lethal neoplasm. Distinguishing MEBN from an atypical cellular blue nevus can be very challenging. We report a diagnostically difficult case of MEBN with lymph node metastases, in which single nucleotide polymorphism array and fluorescence in situ hybridization were used to arrive at the correct diagnosis. It was also analyzed by the recently-introduced proprietary 23-gene expression signature test. To the best of our knowledge, this is the second reported case of MEBN analyzed by the 23-gene expression signature, which provided a false-negative result. More studies are needed to assess the sensitivity and specificity of this test in various melanocytic proliferations.

Scleromatous Changes in an Abdominal Wall Graft: Graft-Versus-Graft Disease, or Chronic Graft Rejection?

Abdominal wall transplants are relatively new procedures that are frequently performed in conjunction with multivisceral transplants. The skin of the abdominal wall transplant is often the first site for graft rejection to manifest itself. Prompt recognition can lead to appropriate treatment before the involvement of the underlying viscera. However, the signs of graft rejection are nonspecific and can overlap with other entities. We present a case of a patient who received a multivisceral and abdominal wall transplant from 2 different donors, who presented with acute and eventually chronic graft rejection of the abdominal wall graft. Serial biopsies performed during the course of her treatment demonstrated progressive sclerotic changes in the dermis. Because these changes were confined to the abdominal wall graft, they could represent either chronic graft rejection or graft-versus-graft disease. To date, graft-versus-graft disease has not been documented in these patients. This case illustrates the possibility that patients with multidonor transplants may be at an increased risk for graft failure secondary to multiple potential etiologies.

Bullous Kaposiform Hemangioendothelioma Masquerading as Aplasia Cutis Congenita.

We present the case of a male infant with violaceous bullae on the scalp that were initially thought to be bullous aplasia cutis but at 3 months of age were diagnosed as a kaposiform hemangioendothelioma. This diagnosis should be considered when evaluating newborns with bullous plaques on the scalp that do not heal in the first 2-3 weeks of life. Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor that typically presents as a violaceous to purpuric plaque at birth or early infancy. It may be associated with Kasabach-Merritt phenomenon (KMP), a potentially life-threatening consumptive coagulopathy.