Leiomyosarcoma of the breast: a case of long survival and late hepatic metastasis.

A case of leiomyosarcoma of the breast that metastasized to the liver 15 years after mastectomy is reported. Leiomyosarcoma appears to have less aggressive biologic behavior than other types of breast sarcomas. Analysis of the reported cases of smooth muscle tumors of the breast revealed some guidelines for the histologic diagnosis of these tumors. Tumors with three or more mitoses per 10 HPF are leiomyosarcomas, and those with no mitotic activity, necrosis, and significant cellular atypia are leiomyomas. The borderline cases are best considered smooth muscle tumors with uncertain malignant potential.