Monarch Disease Ontology entry MONDO_0005058 (leiomyosarcoma) is an uncommon, aggressive malignant smooth muscle neoplasm, usually occurring in post-menopausal women. It is characterized by a proliferation of neoplastic spindle cells. Morphologic variants include epithelioid, granular cell, inflammatory and myxoid leimyosarcomas. Also known as: Leiomyosarcomas, leiomyosarcoma (excluding uterine leiomyosarcoma), leiomyosarcoma - not uterine, leiomyosarcoma, malignant.