Parapelvic cysts: appearance on CT and sonography.

The computed tomographic (CT) and sonographic appearance of 16 patients with parapelvic cysts were retrospectively reviewed. CT revealed a water-density renal hilar mass that did not fill with contrast material after intravenous injection. Sonography demonstrated a cystic renal hilar mass with echogenic walls that did not communicate with the collecting system. The differential diagnosis of renal hilar masses as seen by CT and sonography is discussed.