A müllerian prostatic cyst protruding into the base of the urinary bladder.

The unique appearance of a midline prostatic cyst is reported. The cyst presented as a round-shaped filling defect at the base of the urinary bladder during an intravenous pyelography study. Transabdominal sonography showed the mass to be a midline prostatic cyst. The sonographic features of the mass and its location are the hallmark of a müllerian duct prostatic cyst. Midline prostatic cysts are discussed and the features differentiating müllerian duct cysts from utricle cysts are emphasized.