Parapelvic cyst masquerading as congenital pelvi-ureteric obstruction

Case contributed by Dr Chris O'Donnell

Presentation

PH of left nephrectomy (not for cancer). Now right loin pain

Patient Data

Age: 45
Gender: Male

CT KUB for detection of possible ureteric calculi/obstrcution

CT

Fluid-filled mass projecting from the renal sinus infero-medially in the position of the renal pelvis. This was thought by a colleague to be a congenital PUJ obstruction.

CT IVP with delayed post contrast for clarification

CT

Cystic mass is in fact a parapelvic cyst intimately related to and encircling the upper right ureter. Note mild dilatation of the calyces due to partial obstruction by this cyst causing the patient's right loin pain.

Case Discussion

To confirm the diagnosis of congenital PUJ obstruction it is important to have a delayed contrast study in order to fill the collecting system. Simple parapelvic renal cysts can mimic PUJ obstruction and in rare cases can cause obstruction to the renal pelvis and upper ureter as in this case requiring surgical intervention.

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