Megacalycosis - Challenges in Management and Long-Term Functional Follow-up

Megacalycosis is a rare non-obstructive congenital anomaly of the kidneys. The underlying pathogenesis has not yet been understood. Theories include the coexistence of distinct calyceal developmental stages, malformation of the calyceal structure, and transient, self-limiting obstruction. The management of this condition consists of close sonographic and functional follow-up. It is of the utmost importance to differentiate between an obstructive cause of hydronephrosis, although this can be challenging. Avoiding unnecessary surgical intervention is a crucial objective in this regard. The number of case series is limited, and the follow-up periods are often brief.

The study included pediatric patients with megacalycosis who had been treated at the institution between 2009 and 2024. The extracted data comprised demographics, prior treatments, and follow-up data concerning sonographic and functional tests. The two-sample Student's t-test or the Mann-Whitney-U test were employed, depending on the normality of the distribution of the variables. The statistical analysis was conducted using Microsoft Excel 365.

A total of 19 affected kidneys in 18 patients were identified. The median follow-up period was 5 years (range 1.2-13). All patients exhibited stable renal function at Tc-99m MAG3 scintigraphy. While a plateau phase was evident in the majority of patients following furosemide injection, delayed tracer clearance 40-60 min later was adequate. In cases where the diagnosis was uncertain or where prior surgery had been performed, retrograde pyelography was a valuable additional tool for ruling out obstruction.

This is the largest series with the longest follow-up period of patients affected by megacalycosis to date. The diagnostic process can be challenging. The only appropriate management is non-operative, which preserves renal function. Retrograde pyelography can be a useful additional tool in cases where the diagnosis is uncertain.