What is leiomyosarcoma?

➢ Virtually always arise de novo from the mesenchymal cells of the myometrium. ➢ They are almost always solitary and most often occur in postmenopausal women, in contradistinction to leiomyomas, which frequently are multiple and usually arise premenopausally. ➢ Recurrence after surgery is common, and many metastasize, typically to the lungs, ➢ 5-year survival rate of about 40%. ➢ Leiomyosarcomas typically take the form of soft, hemorrhagic, necrotic masses. ➢ The histologic appearance varies widely, from tumors that closely resemble leiomyoma to wildly anaplastic neoplasms. ➢ Well-differentiated tumors may lie at the morphologic interface between leiomyoma and leiomyosarcoma and are sometimes designated smooth muscle tumors of uncertain malignant potential (STUMP)