Table 1.

Clinico-pathologic features and genetic alterations of Rhabdomyosarcoma subtypes.

RMS Subtype	Age (at presentation)	Location	Morphology	Genetic alterations	Prognosis
Embryonal RMS	Pediatric (0-5)	H&N, GU, GYN tract	primitive to small blue round cells, scattered rhabdomyoblasts, botryoid pattern	Aneuploidy with chromosomal gains and losses; Alterations of the RAS family genes (HRAS, NRAS, KRAS), FGFR4, PIK3CA, NF1 and FBXW7	Favorable
Alveolar RMS	Pediatric (10-20)	Extremities	alveolar pattern, sheets of medium sized cells, scattered giant cells	PAX3-FOXO1 gene fusion; PAX7-FOXO1 gene fusion	Poor
Spindle cell / sclerosing RMS	Infantile, Pediatric and Adults	H&N, paratesticular, extremities	spindle cells in fascicles; sclerosing ‘pseudovascular’ pattern	VGLL2 / NCOA2 gene fusions (infantile) ; MYOD1 gene mutation	Infantile – favorable; MYOD1 mutant - poor
Pleomorphic RMS	Adults	Extremities	pleomorphic rhabdomyoblasts	Complex genetic alterations	Poor