Abstract
Parapelvic cyst (PPC) is a rare cyst that arises from the renal parenchyma and usually does not cause symptoms. However, PPC may cause compression of the pelvicalyceal system resulting in obstructive symptoms. Ultrasonography may not be sufficient to diagnose PPC since they are often misdiagnosed with hydronephrosis, thus computed tomography of the renal is required. In this case, we present, a 27 years old male with a 3 years history of partial urinary retention presented with intermittent loin pain. Hydronephrosis was found on ultrasonography but failed to identify the source of obstruction. A CT scan was conducted and a PPC was confirmed. Nephrostomy was scheduled for ureteral dilation and the patient responded well 4 months after surgery. In this case, we highlight the role of radiology in identifying and differentiating the PPC.