Sclerotic primary cutaneous leiomyosarcoma.

We describe the case of a painful primary cutaneous leiomyosarcoma that developed on the back of a 54-year-old white male over a 6-year period. The lesion had been sampled by punch technique and had been originally diagnosed as cutaneous sclerosis. Histologic examination of excisional tissue revealed a diffuse spindle cell neoplasm in the dermis that extended into the subcutis. There was extensive sclerosis and sparse cellularity in the deep portion and in several zones throughout the tumor. Immunostaining for desmin was negative, although stains for vimentin and smooth muscle actin were both strongly positive. Sclerotic cutaneous leiomyosarcoma should be recognized as a distinct but unusual variant of leiomyosarcoma that may be difficult to diagnose because of extensive sclerosis. Lesions may be painful and should be considered in the differential diagnosis of painful cutaneous neoplasms of the skin.