Congenital Megacalyces

This 10-month old male had a large left kidney, thought to be due to tumour. A CT of the renal tracts was performed, which shows no tumour, but confirms enlargement of the left kidney. The image shown is a posterior view from a 3D reconstruction of the excretory phase of the examination (click image for frontal MIP, a virtual IVP). There are more than the usual number of calyces, and they have a bizarre polygonal, faceted shape.
Congenital megacalyces are thought to be due to developmental hypoplasia of the medullary pyramids. The enlarged, floppy calyces predispose to statis, infection and calculus formation. There is an association with congenital megaureter.
References:
1. Lebowitz RL, Vargas B. The coexistence of congenital megacalyces and primary megaureter. AJR 147:313-316, August 1986
2. Talner LB, Gittes RF. Megacalyces: Further Observations and differentiation from obstructive renal disease. AJR 121(3):473-486, 1974
Credit: Dr Chee Chung Hiew
Credit: Dr Laughlin Dawes
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