A cyst around the renal pelvis that does not obstruct the kidney is known as

• A. Peripelvic cysts
• B. Parapelvic cysts
• C. Renal parenchyma
• D. Renin

Answer: (A)

This item is about recognizing a renal sinus cyst that encircles the pelvis but does not block urine flow. Peripelvic cysts are simple cysts located within the renal sinus that surround the renal pelvis. Because they do not communicate with the collecting system, they typically do not obstruct urinary drainage. On ultrasound they show up as well-defined, anechoic pockets in the renal sinus around the pelvis, and they can resemble hydronephrosis visually, but hydronephrosis involves dilation of the collecting system itself, whereas peripelvic cysts remain discrete cysts not connected to the calyces or pelvis. The other options are not cysts around the pelvis: the renal parenchyma is the functional kidney tissue, and renin is a hormone. A parapelvic cyst is related to the area near the pelvis but is a distinct entity and not the term used for a non-obstructing cyst that surrounds the pelvis.