ABSTRACT
A calyceal diverticulum is an anomalous intrarenal cavity lined by nonsecretory transitional cell epithelium that communicates with the normal collecting system via a narrow diverticular neck.
Although not directly associated with a draining renal papilla, calyceal diverticula fill passively with urine from the adjacent collecting system. Calyceal diverticula are usually less than 10 mm in size, and found incidentally during evaluation for other conditions. Incidence, from 2.1 to 4.5 per 1000 intravenous pyelograms, is similar in adults and children, which suggests an embryologic origin (1). It has been proposed that failure of degeneration of third-and fourth-order divisions of the developing ureteral bud results in a blind-ending outpouching of the collecting system. Others have implicated childhood vesicoureteral reflux, intrarenal rupture of a cyst or abscess, and fibrosing infundibular stenosis (2,3).
