Rhabdomyosarcoma is the most common tumor of the lower genitourinary t
ract in children in the first 2 decades of life, Most cases of genitou
rinary rhabdomyosarcoma are of the embryonal histologic subtype and in
clude tumors of the bladder, prostate, testes and paratesticular sites
, penis, perineum, vagina, and uterus, The natural history, pattern of
metastatic spread, treatment, and prognosis of childhood rhabdomyosar
coma vary with the anatomic site of the lesion, In children with rhabd
omyosarcoma of the bladder or prostate, presenting signs and symptoms
include urinary or fecal retention, dysuria, urinary tract infection,
and hematuria, Paratesticular rhabdomyosarcoma produces painless scrot
al swelling, which may be ignored until the tumor has reached a large
size, Vaginal tumors may manifest as a prolapsing mass in the introitu
s, Radiologic studies of children With genitourinary rhabdomyosarcoma
reflect the nonspecific gross features of the tumor, which may be ill
defined with infiltrative margins or well circumscribed by a pseudocap
sule of compressed tissue, The botryoid variant of embryonal rhabdomyo
sarcoma results when submucosal tumor produces a polypoid mass resembl
ing a cluster of grapes within a hollow structure, Botryoid morphology
is characteristic, but not specific, for rhabdomyosarcoma within the
vagina or urinary bladder, since yolk sac tumor and ''tumoral'' cystit
is may have a similar appearance. Invasion of adjacent structures by t
he primary tumor may make the precise anatomic origin of genitourinary
rhabdomyosarcoma difficult to determine on cross-sectional images, Re
cent refinements in multidisciplinary therapeutic regimens combining c
hemotherapy, radiation therapy, and surgery have dramatically improved
outcome for children with genitourinary rhabdomyosarcoma, Diagnostic
imaging plays an important role in monitoring response to therapy.