Presentation
Suspicion of bilateral hydronephrosis on ultrasound exam.
Patient Data
Innumerable small non-communicating renal sinus cysts of various sizes with no contrast within on excretory phase, stretching and displacing the pelvicalyceal system bilaterally with mild dilatation of the upper calyces.
Small simple hepatic cyst in the left lobe.
A hiatus hernia is noted.
Lipoma of the right external oblique muscle.
Case Discussion
CT urography of peripelvic cysts. This case illustrates the importance of the excretory phase (CT urography) to differentiate hydronephrosis from peripelvic cysts.
Peripelvic cysts are frequently bilateral and originate within the sinus itself and have a lymphatic origin. They appear as fluid-density cysts closely abutting the pelvis and infundibula, and rarely cause functional renal derangement by compression. They may be confused with hydronephrosis on ultrasound or non-enhanced CT, but on the excretory phase of an enhanced CT, the differentiation is obvious.