Benign schwannoma surrounding and obstructing the ureteropelvic junction. First case report.

With a varied presentation and a difficult preoperative diagnosis, schwannoma accounts for only a small percentage of retroperitoneal tumors. Moreover, malignant schwannoma of the adrenal gland, kidney and renal pelvis has previously been described. We report the first case of benign schwannoma causing obstruction by external compression of the ureteropelvic junction. A case report of a male patient who complained of a 3-month history of dull lumbar pain on the right side is reported. Using intravenous pyelogram, sonography and computed tomography a benign tumor of the retroperitoneum was suspected. Upon exploration, the suspected diagnosis of the tumor's retroperitoneal origin was confirmed. After the histological and immunohistochemical studies the diagnosis was verified. The diagnosis, treatment and histological features of benign schwannoma are discussed. A brief review of the literature is also included.