Leiomyosarcoma is a rare, malignant smooth muscle tumor that can affect many body locations, including the uterus, the gastrointestinal system, the bladder, and the skin. This summary focuses on skin. Cutaneous leiomyosarcoma originates from arrector pilorum and it presents as a solitary nodule. The lower extremity is a common location, but lesions have also been reported upon the trunk, anogenital region, upper extremity, and the head / neck. Multiple lesions are unusual and should raise concern for metastatic events, particularly from disease of noncutaneous origin. Cutaneous leiomyosarcoma has a nonspecific clinical appearance and may be mistaken for numerous other diseases. Histopathologic analysis is necessary to establish the diagnosis.

Leiomyosarcoma of the skin is most common in middle-aged patients, with a predilection for men (male to female ratio of 2:1). Prior trauma, radiation exposure, and immunosuppression may predispose one to development of leiomyosarcoma. Cutaneous leiomyosarcoma has a favorable prognosis, particularly relative to visceral forms of disease. Some experts have proposed the term "atypical intradermal smooth muscle neoplasm," and disfavor use of the term "sarcoma," to prevent overtreatment of cutaneously limited disease.