Discussion of Calyceal diverticulum
- AKA "Pyelocalyceal diverticulum"
- Calyceal diverticulum is a relatively uncommon cyst-like lesion, often discovered incidentally during ultrasound examination of the kidneys.
- Calyceal diverticulum is a urine-containing cavity within the renal parenchyma, communicating with the collecting system through a narrow channel.
- Two types are identified:
- One is related to a minor calyx and usually located in the upper pole
- Other is connected with the pelvis or a major calyx in the central portion of the kidney.
- The majority of calyceal diverticulum are small and asymptomatic, and do not require any treatment.
- Calyceal diverticulua may rarely cause urinary tract infection, renal colic, pyuria, hematuria or hypertension.
- Mobile calculi and milk of calcium are characteristic findings in calyceal diverticulum.
 Imaging Findings for Calyceal diverticulum
- Ultrasound examination suggests the diagnosis of calyceal diverticulum and it has a variable appearance.
- The diverticulum may appear as a cyst-like lesion, indistinguishable from a simple cyst.
- Recognition of mobile echogenic material within such a cyst-like structure is considered characteristic of milk of calcium. A cyst-like mass with milk of calcium is presumed to be a calyceal diverticulum.
- CT has an important role in the presence of a complicated cystic mass diagnosed by US without the characteristic features of calyceal diverticulum.
- The demonstration of the layering of contrast medium on delayed images is pathognomonic of these lesions.
- The patency of the diverticulum is demonstrated by the gradual opacification on delayed images.
 External Links
- Rathaus, V, Konen, O, Werner, M, Shapiro Feinberg, M, Grunebaum, M, Zissin, R. Pyelocalyceal diverticulum: the imaging spectrum with emphasis on the ultrasound features. Br J Radiol 2001 74: 595-601.