Primary Cutaneous Melanoma With Sebocyte-like Melanocytes: Case Report and Review of the Literature.

Abstract: Melanocytes with clear vacuolated cytoplasm and scalloped nuclei, resembling mature sebocytes, can occur in congenital, acquired, and blue melanocytic nevi but are rare in malignant melanomas. A case of primary cutaneous melanoma with sebocyte-like cells is reported. The patient was a 75-year-old male patient with a large pigmented lesion located on his right forearm. Histopathologically, the tumor showed two distinctive types of neoplastic cells: atypical melanocytes with eosinophilic cytoplasm and scattered cells with scalloped nuclei, sometimes containing pseudoinclusions, and clear multivacuolated cytoplasm, closely mimicking sebaceous differentiation. Immunohistochemically, sebocyte-like cells were positive for SOX10, PRAME, EMA, and factor XIIIa. A literature review identified six additional cases, three metastatic and three primary melanomas with sebocytes-like cells. Histopathologically, two variants were recognized. In addition to conventional melanoma cells, most of lesions (three metastatic and two primary tumors) contained sebocyte-like melanocytes only; two primary tumors showed sebocyte-like cells mixed to other clear cells, such as intermediate and/or balloon melanocytes.