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.

Leiomyosarcoma of the skin is most common in individuals aged 30-50 years, with a predilection for men (male to female ratio of 2:1). Clinically, leiomyosarcoma presents as a solitary nodule. There are 2 subtypes: subcutaneous and dermal tumors. Subcutaneous leiomyosarcoma, thought to arise from vascular smooth muscles, may carry a worse prognosis as it is more likely to metastasize. On the other hand, dermal leiomyosarcomas, thought to arise from arrector pili muscle, are more likely to recur locally, but are less likely to metastasize.

The lower extremities are a common location, but lesions have also been reported upon the trunk, anogenital region, upper extremities, and the head / neck. A recent study shows that lesions on the extremities are more common in White individuals, while lesions on the trunk are more common in Black individuals. Head and neck tumors are more common in American Indian and Alaskan Native individuals. Multiple lesions are unusual and should raise concern for metastases, particularly from disease of noncutaneous origin.

Prior trauma, radiation exposure, and immunosuppression may predispose one to development of leiomyosarcoma. Development of leiomyosarcoma from precursor lesions (leiomyoma) and scar tissue has been reported as well.

Cutaneous leiomyosarcoma has a favorable prognosis relative to visceral forms of disease. While the most common sites for metastasis are the lungs and skin, metastasis to the lymph nodes, colon, and bone has been reported as well.