Embryonal Rhabdomyosarcoma

Between 25% to 30% of all rhabdomyosarcomas arise in the genitourinary tract, especially in children. Bladder, prostate, paratestis, and vagina are the most commonly affected locations. The image shows a condensed layer of tumor cells (cambium layer) just beneath the urothelial surface. The deeper aspects of the tumor have hypocellular myxoid matrix. This embryonal rhabdomyosarcoma is from a 23 month old boy who presented with hematuria and a large mass at the bladder outlet. Inguinal lymph nodes and bone marrow were positive for metastases. Following chemotherapy, he underwent partial cystectomy.