Calyceal diverticulum

Clinical History

A 49-year-old female patient came with history of pain in the right abdomen for two weeks.

Imaging Findings

Supine abdominal plain film showed multiple small clustered calcifications in the lower pole of the right kidney (Fig. 1).
Intravenous urography after 15 minutes delay showed a cortical cystic-like lesion filled with small stones pooling of contrast media in the lower pole of the right kidney (Fig. 2).
Computed Tomography urography showed, during the excretory phase, a contrast media-containing cavity within the cortical kidney communicating with the minor lower calix, confirming calyceal diverticulum diagnosis (Fig. 3).

Discussion

Calyceal diverticulum is a urine-containing cavity within the renal parenchyma, comunicating with the collecting system through a narrow channel. They are lined by transitional epithelium, which is the same tissue that lines the urinary tract. These diverticula may originate from embryogenesis, blunt renal trauma or obstruction. The urinary stasis may predispose the patient to stone formation or urinary tract infections.
There are three types: type one originates from minor calyx, type two originates from the calyceal infundibulum and type three from the renal pelvis. The majority of cases are unilateral, and are often discovered incidentally on imaging studies. They occur in any part of the kidney, but usually originate from upper pole calyx (the superior (70%). [1]

Almost most calyceal diverticula are aymptomatic. In the absence of clinical symptoms or complications, calyceal diverticula can be managed conservatively. [2]

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. It is important to scan in different positions to demonstrate gravitational change of echogenic material (stones or milk of calcium), in these cases the diagnosis is evident, without needing another imaging study. With conventional abdominal radiography, a calyceal diverticulum without stones would not be detectable. Abdominal plain film shows clustered stones, which are sometimes difficult to differentiate from renal calculi, gallstones and milk of calcium cysts. On intravenous urography, the cystic cavity becomes progressively opacified, giving the appearance that the stones are growing. This is referred to as the “growing calculus” sign. Calyceal diverticulum opacifies late because it fills from the opacifying collecting system. On CT urography, the diverticulum shows a fluid density with layering stone material on unenhanced CT. Delayed images confirm a connection to the adjacent collecting system. [3, 4]
Treatment of symptomatic calyceal diverticulum is controversial. Traditionally open exploration with suture ligation of the calyceal neck and fulguration of the diverticulum was recommended. Laparoscopy has been trialled but requires advanced laparoscopic skills due to its technical difficultly. The percutaneous treatment is a suitable option for retrieval of calculi and ablation of the defect. [5]

Calyceal diverticulum is a radiological diagnosis; the importance of this condition lies in its recognition. Treatment usually is indicated if there is infection or stone formation.

Differential Diagnosis List

Final Diagnosis

Calyceal diverticulum with stones

URL:	https://www.eurorad.org/case/10253
DOI:	10.1594/EURORAD/CASE.10253
ISSN:	1563-4086