Histology There are 2 major histologic subtypes of rhabdomyosarcoma: Embryonal: Characterized by loss of heterozygosity on chromosome 11p15.5 Alveolar: Associated with translocation t (2; 13), which fuses the PAX3 gene with the FOXO1 (FKHR) gene, and t (1; 13), which fuses the PAX7 gene with the FOXO1 (FKHR) gene Location Although rhabdomyosarcoma can occur almost anywhere in the body, the cancer has a predilection for several sites (3): Head and neck region (about 35%), usually in the orbit or nasopharyngeal passages: Most common among school-aged children Genitourinary system (about 25%), usually in the bladder, prostate, or vagina: Usually occurring in infants and toddlers Extremities (about 20%): Most common among adolescents Trunk / miscellaneous sites (about 20%) Approximately 15 to 25% of children present with metastatic disease.