Axillary and perianal leiomyosarcoma: report of two cases.

Soft tissue leiomyosarcoma is a relatively rare malignant tumor. It may be difficult to be distinguished from gastrointestinal stromal tumors and Schwann cell neoplasms. To make a correct identification of soft tissue leiomyosarcoma, immunostaining with several smooth muscle differentiation markers (actin, calponin and desmin), and negative staining results with S100 (to rule out Schwann cell neoplasm), c-kit and CD34 (to rule out gastrointestinal stromal tumors) is needed. Prompt diagnosis and referral are desirable, since the size of the tumor at presentation is a continuous variable for the risk of local recurrence and metastatic disease. Chemosensitivity varies according to the tumor subtype, and the tumor grade, the patient's age, performance status, and the timing of metastatic disease further influence the likelihood of a response and survival. Chemotherapy is palliative for most patients with unresectable or metastatic disease. Ifosfamide and doxorubicin are routinely used in this setting; doxorubicin as a single agent is considered the drug of choice.