Benign Pigmented Schwannoma of the Great Omentum: Report of a Rare Case and Review of the Literature.

Schwannoma in the abdomen is an uncommon neoplasm that occurs most frequently in the cranial and peripheral nerves; it is extremely rare in the great omentum and only 6 cases of schwannoma of the great omentum have been observed previously. We report the case of a schwannoma found in the great omentum of a 55-year-old man who was treated with laparoscopic surgery. Though it was difficult to diagnose preoperatively, the tumor showed malignant potential by rapidly increasing in size. Histologically it was configured by a well-encapsulated round mass measuring 30 × 18 × 15 mm in diameter. Immunohistochemically most of the neoplastic cells reacted moderately to NSE, NCAM and S-100 protein. We document the clinicopathological study of a schwannoma of the great omentum, followed by a review of the literature.