Wilms' tumor in horseshoe kidney: presentation due to ureteropelvic junction obstruction.

Children with horseshoe kidney usually develop urinary tract symptoms and often require operative correction of the anomaly. The incidence of Wilms' tumor in horseshoe kidney is higher than that for the general population. We present the case of a child whose Wilms' tumor was diagnosed early because of ureteropelvic junction obstruction secondary to a horseshoe kidney. A high index of suspicion should be maintained for Wilms' tumor in any child with a horseshoe kidney.