SMALL-CELL EPIDERMOID CARCINOMA WITH MELANOCYTE COLONIZATION ARISING IN A MATURE OVARIAN CYSTIC TERATOMA

A case of small-cell epidermoid carcinoma, a rare tumor of the aerodig estive tract, is presented arising in a mature cystic teratoma of the ovary in a 69-year-old woman. Microscopically the small-cell epidermoi d carcinoma had a uniform cell population with focal differentiation i nto keratinous tells. Both the small and keratinized cells were positi ve for epithelial membrane antigen and CAM 5.2 but negative for viment in and neuroendocrine markers. This tumor is different from other rece ntly described primary and metastatic small-cell tumors of the ovary. Furthermore, this small-cell epidermoid carcinoma behaved in a nonaggr essive fashion. Melanocyte colonization seen in the small-cell epiderm oid carcinoma areas of the tumor was a result of its invasion of preex istent areas of a teratoid blue nevus. The staining pattern of HMB-45 demonstrated that pigment was transferred to, but not produced by, the neoplastic small cells.