Megacalycosis: a rare condition.

Megacalycosis is an extremely rare condition. We report our experience with two cases and discuss its pathogenesis, diagnosis and management in children. Our two patients had presented a prior diagnosis of congenital hydronephrosis. An increased number of calyces with a significant disproportion between the degree of calyceal dilatation and a mildly dilated renal pelvis were found in each case. Megacalycosis must be considered in the differential diagnosis of congenital hydronephrosis, polycalycosis, and infundibular stenosis. The diagnosis is suggested by ultrasound and confirmed by diuretic renography, intravenous pyelography or magnetic resonance urography. Voiding cystourethrography should be performed to rule out vesicoureteral reflux. A high index of suspicion is needed for the diagnosis of this condition.