Monarch Disease Ontology identifier MONDO_0003349 (central nervous system leiomyosarcoma) is an aggressive malignant smooth muscle neoplasm, arising from the central nervous system. It is characterized by a proliferation of neoplastic spindle cells. Also known as: CNS leiomyosarcoma, leiomyosarcoma of CNS, leiomyosarcoma of central nervous system, leiomyosarcoma of the CNS, leiomyosarcoma of the central nervous system.