Leiomyosarcoma of male breast originating in the nipple.

A case of leiomyosarcoma of the breast in a 53-year-old man originating in the erectile musculature of the nipple is presented. The tumor assumed roughly the conical configuration of the nipple musculature and was limited to the mammary gland. Ultrastructural study of the tumor revealed ncoplastic smooth muscle cells with typical myofilaments.