Large pelvic schwannoma causing bilateral hydronephrosis.

Schwannoma is a tumor originating from neural sheath schwann cells. We report here a case of benign retroperitoneal schwannoma that caused bilateral ureterohydronephrosis. The retroperitoneal localization in the present case is unusual. The tumor was 21 x 18 x 11 cm in dimension and reached from the prostate to the umbilical level. Even though the patient had bilateral hydronephrosis, the renal function tests results were in the normal range. Complete surgical excision was achieved by anterior laparotomy. Histological and immunohistochemical studies confirmed the diagnosis. At 6 months follow-up there was no evidence of recurrence and renal function test results were normal.