Giant hydronephrosis due to ureteropelvic junction obstruction in a child: CT and MR appearances

Giant hydronephrosis caused by congenital ureteropelvic junction (UPJ) obstruction is a rare urological entity in childhood. We report a case of giant hydronephrosis in a 12-year-old boy presented with abdominal distension. Radiological features of this rare entity are discussed with an overview of sonographic findings, especially including CT and MR appearances. The current literature is also reviewed.