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

Abstract

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.

Large benign schwannoma of the greater omentum with synchronous cervical cancer: A case report

“…While benign lesions (with or without malignant potential) include lipoma, leiomyoma/leiomyoblastoma, mesothelioma, solitary fibrous tumor, and extra GIST. They behave sporadically with a diverse pathologic spectrum, and their true incidence remains uncertain [ 4 , 11 , 12 ].…”

“…There are more reported cases of lesser omental schwannoma compared to those in the greater omentum due to the paucity of nervous tissue in the latter. Regardless of location, they can undergo malignant transformation [ 4 , 12 ].…”

“…It is worth noting that this was present in all patients with malignant pathology. Only 1 patient was asymptomatic while the remainder presented with a palpable abdominal mass with fullness [ [4] , [5] , [6] , [7] , [8] , [9] , 13 , 14 ]. Tumoral bleeding was reported in 2 cases which caused hypovolemic shock, and intraoperative death due to heart failure, respectively [ 13 , 14 ].…”

“…Other locations commonly include the extremities and trunk, and less frequently in the mediastinum, gastrointestinal tract, retroperitoneum, adrenal, and thyroid glands [ 1 , 3 ]. Even rarer are schwannomas of the greater omentum with only 16 reported cases in the literature [ [4] , [5] , [6] , [7] , [8] , [9] ]. Herein, we report for the first time a synchronous presentation of a large benign schwannoma of the greater omentum and adenocarcinoma of the cervix in a young female.…”

Schwannoma in descending colon: presentation of a neoplasm in a rare location

“…Microscopically they are arranged in a pattern of intertwined bundles surrounded by an infiltrate of lymphoid cells with germinal centres and small foci of cellular atypia with low mitotic activity (10). An immunohistochemical study is very useful for a differential diagnosis with other lesions such as GISTs, GANTs (a variant of GISTs derived from the autonomic nerves), leiomyomas or leiomyosarcomas, which can show a more aggressive behaviour (11). Schwannomas usually express a positive reaction for S-100, vimentin and GFAP, but no reactivity for the transmembrane receptor tyrosine kinase known as c-KIT or CD117, the precursor cell antigen of the haematopoyetic system CD34, actin or cytokeratins, which do appear more typically in GISTs, GANTs or muscle tumours (12,13).…”