Schwannoma of the psoas: An unusual cause of abdominal pain.

Schwannomas are usually benign tumours arising from Schwann cells of peripheral nerve sheath. Retroperitoneal location is extremely rare compromising 0.5-5% of all schwannomas, except in patients having von Recklinghausen's disease, in whom retroperitoneal location is more frequent and malignant cases are known to occur. Complete surgical excision with negative margins is the definitive treatment on which the diagnosis is usually made due to nonspecific radiologic appearance. In this article we would like to present an unusual cause of recurrent, abdominal pain in an eighty-six-year-old male.