Progression of dermatofibrosarcoma protuberans to malignant fibrous histiocytoma: report of a case with implications for tumor histogenesis.

A 79-year-old woman required amputation of her left leg for the control of a rapidly growing malignant fibrous histiocytoma. This tumor had developed at the precise site of repeated recurrence of a previously diagnosed dermatofibrosarcoma protuberans. Biopsy specimens from the recurrences revealed a gradual change in appearance from dermatofibrosarcoma protuberans to malignant fibrous histiocytoma.