Solitary Schwannoma in the Psoas Muscle

The vast majority of schwannomas occur on cranial nerves, and rarely in the retroperitoneum. Solitary schwannoma in the psoas muscle is extremely rare. The authors present a case of retroperitoneal neoplasm in the psoas muscle identified as schwannoma which is not associated with von Recklinghausen's disease. A 68 years old female patient was admitted because of low back pain and weakness at the left leg. CT and MRI revealed a large cystic mass with well-defined margin and multiple internal septation within the left psoas muscle. The tumor was totally extirpated and histologically confirmed as a schwannoma.