A benign mesenchymal neoplasm arising from smooth muscle tissue. The disease is benign smooth muscle neoplasm (Monarch Disease Ontology entry MONDO_0006106). Also known as: benign neoplasm of smooth muscle, benign neoplasm of the smooth muscle, benign smooth muscle tumor, benign smooth muscle tumour, benign tumor of smooth muscle, benign tumor of the smooth muscle, benign tumour of smooth muscle, benign tumour of the smooth muscle.