Childhood rhabdomyosarcoma is a cancer that forms in muscle tissue. It is the most common type of soft tissue sarcoma in children and can begin in many places in the body.
There are three main types of rhabdomyosarcoma: embryonal, which occurs most often in the head and neck area or in the genital or urinary organs; alveolar, which occurs most often in the arms or legs, chest, abdomen, genital organs, or anal area; and anaplastic, which is rare in children.
Certain genetic conditions increase the risk of childhood rhabdomyosarcoma including Li-Fraumeni syndrome, pleuropulmonary blastoma, neurofibromatosis type 1 (NF1), and Beckwith-Wiedemann syndrome. In most cases, the cause of rhabdomyosarcoma is not known.
Source: National Cancer Institute