[Prolapsed ureterocele: a diagnosis to be considered for a vulvar mass in an infant: case report].

Ureterocele is a relatively common malformation of the urinary system in children; however, the ureterocele prolapse through the urethra is an extremely rare presentation. Urological nuclear magnetic resonance is the test of choice for definitive diagnosis. Initial treatment of a prolapsed ureterocele involves decompression of the mass. We report the case of a 7-month-old infant with duplication of the collecting system and right ectopic ureterocele appearing as a vulvar mass.