Calyceal diverticulum of the kidney in pediatric patients - Is it as rare as you might think?

OBJECTIVE: Calyceal diverticulum (CD) is rarely diagnosed in children. It mimics other cystic lesions of the kidney and may be very difficult to identify. Displaying the communication of these fluid-filled cavities with the collecting system of the kidney via imaging methods is the key diagnostic method. The purpose of this study is to determine the presence of calyceal diverticulum in pediatric patients followed up due to simple renal cyst and/or parapelvic cyst. MATERIAL, AND METHOD: Patients who were newly diagnosed or being followed up with the ultrasonographic diagnosis of simple cyst(s) or parapelvic cyst(s) in the Department of Pediatric Nephrology of Izmir University of Health Sciences Tepecik Training and Research Hospital between December 2015 and July 2018 were included in the study. Age, gender, admission symptoms, recurrent urinary tract infections, stone disease, trauma history, accompanying urinary system and systemic anomalies, localization, and size of the cyst(s) at admission and during follow-up, treatment type and developing complications were noted. Contrast MR urography was applied to all patients. RESULTS: A total of 43 patients [mean age:132 ± 54.9 (12-228) months] including 25 girls were enrolled in the study. The mean follow-up period was 36. 74 ± 19 (1-90) months. The cysts were located mostly in the right kidney and also in the upper pole of the kidney. The mean cyst size was 20.4 ± 11 (8-58) mm at admission, and comparably 20.3 ± 8.6 (10-45) mm at the end of the follow-up. In contrast MR urography, a total of 16 cases were observed at first glance to be associated with pelvicalyceal system. However, in the postcontrast images taken at the 5th minute it was determined that 9 of them were compatible with calyceal diverticulum. CONCLUSION: Although it is thought that well-circumscribed solitary renal fluid collections may be thought to be a simple renal cyst at first glance, the differential diagnosis of calyceal diverticulum (CD) should be absolutely kept in mind. Contrast studies and late-phase postcontrast images are needed for the diagnosis of CD. Although the standard management of CDs in children is conservative, surgical intervention may be rarely required.