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Indian Journal of Medical Sciences, Vol. 59, No. 9, September, 2005, pp. 403-405 Letter To Editor Diagnostic dilemma: Calyceal diverticulum vs complicated cyst Surendrababu NRS, Govil S Department of Radio Diagnosis, Christian Medical College Hospital, Vellore - 632 004, Tamilnadu Code Number: ms05061 Sir, A 35-year-old woman presented with right lower abdominal pain and tenderness without hematuria or lower urinary tract symptoms. Abdominal ultrasonography(USG) revealed a right renal parenchymal cyst with a focus of posterior wall calcification. CT scan [Figure - 1] done for further evaluation of this complicated cyst, showed a well-defined 2 cm cystic lesion in the upper pole of the right kidney with a plaque like curvilinear peripheral calcific density in the posterior wall. The cyst was situated in the renal parenchyma with its medial margin abutting the renal sinus. This proximity to the renal sinus raised the suspicion of a calyceal diverticulum containing a calculus. Prone CT scans taken 20 minutes before and after intravenous contrast injection, demonstrated movement of the calculus and contrast opacification of the cyst, confirming cyst communication with the collecting system. Another patient, a 25-year-old lady with recurrent left loin pain and urinary tract infection was found to have a left renal parenchymal cyst with posterior wall calcification on USG. CT scan showed a 2.8 cm left renal cyst abutting the renal sinus with curvilinear calcification in the posterior wall. Subsequent intravenous urogram (IVU) [Figure - 2] revealed a mobile calculus within a calyceal diverticulum, which filled with contrast on delayed imaging. Anatomically and radiologically the renal cyst and calyceal diverticulum are related, in fact may be considered as different evolutionary forms of the same congenital disorder. Calyceal diverticulum is a urine-containing cavity within the renal parenchyma communicating with the collecting system through a narrow channel and is lined by transitional epithelium.[1] The incidence is 2.1 to 4.5 per 1000 IVUs and are bilateral in 3% of cases.[1] It rarely causes loin pain, urinary tract infection, renal colic, pyuria, haematuria or hypertension.[2] The aetiology is probably congenital, resulting from failure of regression of the third or fourth division of the ureteric buds of the Wolffian duct.[1] Mobile calculus is a characteristic finding in calyceal diverticulum.[3] A renal cystic lesion detected on USG or CT with plaque-like calcification along the posterior wall should raise the possibility of a calyceal diverticulum with a mobile calculus. Demonstration of the mobility of the calcific focus suggests the diagnosis of a calyceal diverticulum since only cysts communicating with the collecting system tend to form calculi, while renal cysts have calcium in other immobile forms such as mural or septal calcification. Calcification has been reported in 1%-3% of cases of renal cysts.[4] Thick and nodular calcification, wall thickening, or nodularity without enhancement in renal cysts is considered as a complicated cyst of Bosniak Type 2F.[5] Management of the calyceal diverticulum and type 2F lesions differ; while patients symptomatic with the former require percutaneous endoscopic calculus removal, a type 2F cyst only needs close follow up. These two cases demonstrate a deceptive similarity between calyceal diverticulum and complicated cyst on USG and CT. However in both cases, demonstration of the proximity of the cyst to the renal sinus, mobility of the calcific density in the cyst, and communication with a calyx revealed the true diagnosis of a calculus within a calyceal diverticulum. In conclusion, caution should be exercised while diagnosing posterior wall calcification in renal cysts abutting the renal sinus found on USG and CT scan. An attempt should be made to resolve calcific density mobility in the cyst. If USG is equivocal, supine and prone CT sections may reveal the mobile nature of the calcification and make the diagnosis of a calyceal diverticulum with calculus rather than a complicated cyst [Figure - 3]. REFERENCES
Copyright 2005 - Indian Journal of Medical Sciences The following images related to this document are available:Photo images[ms05061f3.jpg] [ms05061f1.jpg] [ms05061f2.jpg] |
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