Pseudo-crossed renal ectopia secondary to ureteropelvic junction obstruction.

To our knowledge we report the first case of pseudo-crossed renal ectopia without an apparent displacing retroperitoneal mass that was documented on sequential radiological studies. Ureteropelvic junction obstruction of the crossed kidney appeared to be the cause of pseudo-crossed renal ectopia. Our case is compared with previously described instances of pseudo-crossed renal ectopia and the pathophysiological basis of this condition is discussed.