Which cyst is a cortical lymphatic cyst bulging into the central sinus and does not connect to the collecting system?

Which cyst is a cortical lymphatic cyst bulging into the central sinus and does not connect to the collecting system?

• A. Parapelvic Cyst
• B. Peripelvic Cyst
• C. Pyelogenic Cyst
• D. Milk of Calcium Cyst

Answer: (A)

Parapelvic cysts are lymphatic in origin and sit in the renal sinus near the hilum. They bulge into the central sinus rather than filling or communicating with the collecting system, so the urine pathway stays separate from the cyst. On ultrasound this appears as an anechoic structure projecting into the sinus without connecting to the pelvis or calyces. This noncommunicating, sinus‑bulging characteristic distinguishes parapelvic cysts from pyelogenic cysts, which do connect with the collecting system, and from milk of calcium cysts, which show gravity‑dependent layering of echogenic material. Peripelvic cysts surround the pelvis but their hallmark feature is not a central sinus bulge.

Parapelvic cysts are lymphatic in origin and sit in the renal sinus near the hilum. They bulge into the central sinus rather than filling or communicating with the collecting system, so the urine pathway stays separate from the cyst. On ultrasound this appears as an anechoic structure projecting into the sinus without connecting to the pelvis or calyces. This noncommunicating, sinus‑bulging characteristic distinguishes parapelvic cysts from pyelogenic cysts, which do connect with the collecting system, and from milk of calcium cysts, which show gravity‑dependent layering of echogenic material. Peripelvic cysts surround the pelvis but their hallmark feature is not a central sinus bulge.