Rhabdomyosarcoma is the most common soft tissue sarcoma in children, accounting for 3% to 4% of all cases of childhood cancer, approximately 350 new cases diagnosed each year in the United States.1,5 Rhabdomyosarcoma is more common in males and whites, and two-thirds of cases occur in patients under the age of 10 years.251,252 Since the inception of the Intergroup Rhabdomyosarcoma Study Group (IRSG) in 1972 (now called the Soft Tissue Sarcoma Committee of COG), more than 4,000 patients have been treated in five well-designed multidisciplinary prospective trials for rhabdomyosarcoma that have boosted the survival rates of these patients from 30% to 72% (Fig. 123.2).253,254

The majority of cases of rhabdomyosarcoma are sporadic, but genetic and environmental factors have been associated with a predisposition for the development of this disease, including the Li-Fraumeni syndrome, neurofibromatosis type 1, Costello syndrome, Beckwith-Wiedemann syndrome, and parental use of marijuana and cocaine.254–256 Because rhabdomyosarcoma arises from a primitive mesenchymal cell, it can be found in multiple areas of the body, but the most commonly affected anatomic regions by order of decreasing frequency are the head and neck (including the orbit and parameningeal areas), 35%, genitourinary tract (including the bladder, prostate, vagina, vulva, uterus, and paratesticular area), 22%, and extremities, 18%.5,256

Rhabdomyosarcoma has been traditionally classified into three histologies, consisting of embryonal (including botryoid), alveolar, and pleomorphic subtypes.6,257 The two ...