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

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.