Computed tomography of prostatic and bladder rhabdomyosarcomas.

Rhabdomyosarcoma represents the most common soft tissue sarcoma in children. The CT findings in five patients with pelvic rhabdomyosarcoma are reported. In the three male patients the primary tumor originated in the prostate gland whereas in the two female patients the bladder was the primary site. The CT findings in the prostatic tumors included an enlarged, inhomogeneous prostatic mass with invasion of the perirectal fat. In two of these patients there was thickening of the levator ani muscle and one showed tumor invasion through the ischiorectal fossa and sciatic and obturator foramina into the pelvic musculature and bone. In the two patients with bladder tumors, one showed a large mass adjacent to the lateral aspect of the bladder and ascites, suggesting an ovarian primary tumor. The other patient with sarcoma botryoides (a subtype of rhabdomyosarcoma) had a diffusely thickened bladder. Two patients have had a follow-up CT demonstrating tumor regression posttherapy. The characteristically large size of these masses and propensity for local invasion in a young patient are typical features of pelvic rhabdomyosarcoma.