Monarch Disease Ontology identifier MONDO_0003292 (anus leiomyoma) is a well-circumscribed benign smooth muscle neoplasm arising from the anus. It is characterized by the presence of spindle cells with cigar-shaped nuclei, interlacing fascicles, and a whorled pattern. Also known as: anal leiomyoma, leiomyoma of anus, leiomyoma of the anus.