A rare aggressive rhabdomyosarcoma occurring in children. The neoplasm is characterized by the presence of bizarre round, spindle, and polygonal cells. The disease is childhood pleomorphic rhabdomyosarcoma (MONDO_0004233, a Monarch Disease Ontology term). Also known as: Pleomorphic rhabdomyosarcoma, childhood anaplastic rhabdomyosarcoma, paediatric pleomorphic rhabdomyosarcoma, pediatric pleomorphic rhabdomyosarcoma, pleomorphic childhood rhabdomyosarcoma, pleomorphic rhabdomyosarcoma of childhood.