Diferenciando bacterias Gram+ y Gram-

Ureteral extension of Wilms tumor (WT) is a rare occasion. The association of duplex collecting system and WT is extremely rare. Ureteral extension of WT in a duplex collecting system is an unreported entity to date. A 10-year-old girl presenting with WT extending into upper pole ureter of duplex system is reported to emphasize the importance of preoperative diagnosis to plan step by step surgery in this rare coincidental situation.