An aggressive malignant smooth muscle neoplasm, arising from the prostate. It is characterized by a proliferation of neoplastic spindle cells. The disease is prostate leiomyosarcoma (Monarch Disease Ontology identifier MONDO_0003368). Also known as: leiomyosarcoma of prostate, leiomyosarcoma of prostate gland, leiomyosarcoma of the prostate, prostate gland leiomyosarcoma.