Sebaceous carcinoma arising on actinic keratosis.

We report two cases of sebaceous carcinoma arising on actinic keratosis. The first patient, a 75-year-old female, had a granuloma pyogenicum-like tumor on her left temple, and the second patient, an 81-year-old female, developed a tumor with erythema on her left cheek. In both cases, histopathological examination revealed findings typical of sebaceous carcinoma in the center of the tumors, and in the periphery, actinic elastosis and intraepidermal proliferation of squamoid atypical cells without vacuolation was observed. Immunohistochemical examinations using six antibodies also revealed that neoplastic cells of both cases demonstrated sebaceous differentiation. These cases suggest that extraocular sebaceous carcinoma may arise from actinic keratosis.