A malignant mesenchymal tumor with skeletal muscle differentiation affecting the anus. The disease is anus rhabdomyosarcoma (MONDO_0002864). Also known as: anal rhabdomyosarcoma, anus rhabdomyosarcoma (disease), rhabdomyosarcoma (disease) of anus, rhabdomyosarcoma of anus, rhabdomyosarcoma of the anus.