Rhabdomyosarcoma (RMS) is a form of soft tissue tumor. It arises from skeletal muscle progenitor cells, and while they can occur in any area of the body, they commonly occur where there is no skeletal muscles, such as the sinuses, neck, and genitourinary system. There are two main sub-types, embryonal and alveolar, based on the embryo stage they resemble.
RMS is diagnosed in about 350 children annually, which makes it the most common childhood sarcoma. By contrast, RMS is very rare in adults, with under 500 cases being documented in the last 30 years in adults in the US and Europe. The majority of cases are diagnosed in children under 5, who also have the best prognosis. Embryonal RMS has a higher survival rate than alveolar or undifferentiated, and prognosis also varies with site.
While most of the causes of RMS are unknown, 10-25% of cases have an underlying genetic risk factor, such as Li Fraumeni, Costello, or Beckwith-Weiderman syndromes.
Sources: X, X, X