# Calyceal Diverticulum: A Cystic Lesion Mimicking a Urinary Tract Infection

## TL;DR

A rare kidney condition called calyceal diverticulum can mimic a urinary tract infection in children and requires advanced imaging for accurate diagnosis.

## Contribution

This case highlights UTI as a potential first clinical manifestation of calyceal diverticulum in pediatric patients.

## Key findings

- Calyceal diverticulum was diagnosed using MRI after presenting as a urinary tract infection.
- UTI can be the initial clinical manifestation of calyceal diverticulum in children.
- Advanced imaging is crucial for diagnosing calyceal diverticulum in atypical renal cystic lesions.

## Abstract

Calyceal diverticulum (CD) is an uncommon renal anomaly in children and often mimics other cystic lesions, making diagnosis challenging. We report the case of a nine-year-old boy evaluated during follow-up after an episode of acute pyelonephritis. He remained asymptomatic, with normal examination findings and appropriate growth. Renal ultrasound revealed a non-vascularized cystic lesion with heterogeneous content in the upper pole of the right kidney. Subsequent magnetic resonance imaging demonstrated communication with the collecting system, confirming the diagnosis of CD. While typically asymptomatic, CD may initially present with complications such as urinary tract infection (UTI). Identification relies on imaging modalities capable of visualizing the diverticular communication with the calyceal system. Management in pediatric patients is generally conservative, with surgical intervention reserved for recurrent infection, abscess formation, persistent pain, gross hematuria, or progressive enlargement. This case highlights that UTI is a complication of calyceal diverticulum and could be its first clinical manifestation. It further emphasizes the importance of including CD in the differential diagnosis of atypical pediatric renal cystic lesions and reinforces the crucial role of advanced imaging in establishing a definitive diagnosis.