[A case of retroperitoneal schwannoma extracted by a nerve sparing procedure under microscopic surgery].

We report a case in which we extracted retroperitoneal schwannoma by a nerve sparing procedure under microscopic surgery. A 63-year-old male was diagnosed with left ureter stone and left hydronephrosis. A left retroperitoneal tumor was found by the abdominal ultrasound sonography. Abdominal computed tomography and magnetic resonance imaging revealed the mass 20 mm in diameter in the retroperitoneal cavity. We considered that the tumor arose from the left femoral nerve, and removed it under microscopic surgery. There was no malignancy. There was neither recurrence nor neuropathy after operation. Since it is rare to find the origin nerve of schwannoma before operation, we report our experience.