Cystic retroperitoneal renal hilar ancient schwannoma: Report of a rare case with atypical presentation masquerading as simple cyst

Schwannoma is a benign soft tissue tumor of neural origin arising from the Schwann cells of the neural sheath. It has rarely been reported in renal or perirenal region. The preoperative diagnosis has mostly been confused with renal cell carcinoma in this location in most previous reports. We report a case that presented with a large "simple cystic" mass at the renal hilum. The preoperative differential diagnosis included hilar renal cortical cyst, renal sinus cyst, ureteropelvic junction obstruction (UPJO), or even a hydatid cyst. The final diagnosis was clinched only on histopathological examination.