Immunohistochemical localization of S100 protein in skin tumors.

We applied a peroxidase-antiperoxidase technique for S100 protein to 73 tumors of skin and skin adnexa. These included 15 eccrine tumors, 11 apocrine tumors, 18 tumors with differentiation toward hair, two sebaceous adenomas, one mixed tumor of the scalp, ten dermatofibromas, ten basal cell carcinomas, five squamous cell carcinomas, and one clear cell acanthoma. Consistent results were obtained. Occasional cells in eccrine tumors showed strong positive staining, as did the Langerhans' cells in the squamous cell carcinomas and the clear cell acanthoma. The cells of the apocrine tumors showed moderate to weak staining, and the tumors with differentiation toward hair, the sebaceous adenomas, and the mixed tumor of the scalp showed uniform negative staining, as did basal cell carcinomas and dermatofibromas.