[A case of schwannoma in psoas muscle]

We report a case of schwannoma in psoas muscle, difficult to make a preoperative differential diagnosis from multilocular renal cyst in a 44-year-old woman. She complained of epigastric discomfort, and abdominal computerized tomography revealed a left multi-cystic renal tumor. Drip infusion pyelography showed the tumor displacing the left kidney superiorly, and pushing the left ureter medially. Magnetic resonance imaging demonstrated that the tumor structure was multilocular. At the operation, the tumor was observed in psoas muscle and was revealed as schwannoma in microscopic findings.