A malignant mesenchymal tumor with skeletal muscle differentiation affecting the rectum. The disease is rectum rhabdomyosarcoma (Monarch Disease Ontology id MONDO_0002853). Also known as: rectal rhabdomyosarcoma, rectum rhabdomyosarcoma (disease), rhabdomyosarcoma (disease) of rectum, rhabdomyosarcoma of rectum, rhabdomyosarcoma of the rectum.