Gastrointestinal Stromal Tumor of the Lesser Omentum: Report of a Case

Abstract

We describe herein an extremely unusual case of a gastrointestinal stromal tumor (GIST) of the lesser omentum. A 45-year-old man was admitted to our hospital with an intra-abdominal mass that was subsequently misdiagnosed as a submucosal tumor of the stomach. The tumor arose from the lesser omentum and was removed without difficulty. Histologically, the tumor was composed of spindle-shaped cells with an interlacing bundle pattern, and immunohistochemical examination showed that it was positive for myeloid stem cell antigen (CD34), but negative for HHF35 and S-100 protein. These findings were consistent with a GIST lacking myogenic features and neural attributes. The patient had an uneventful postoperative course, and was free of recurrence when last seen 11 months after his operation.

Malignant tumor, of the gastrointestinal stromal tumor type, in the greater omentum

“…No postoperative recurrence of omental GISTs has ever been reported. [2][3][4] It is only in the present patient that omental GIST, with multiple liver metastases, had a poor outcome, despite complete resection of the tumor. In most cases, the clinical behavior of a GIST can be predicted with relative accuracy based on a combination of tumor size and mitotic activity.…”

“…[1][2][3][4][5] To our knowledge, only 19 omental GISTs have ever been reported. The tumors occurred in 8 men and 11, women ranging in age from 31 to 89 years (median, 60 years).…”

“…[2][3][4][5][11][12][13][14] A low mitotic rate is not considered to rule out malignant behavior in GISTs. 1,2,11 Despite the low mitotic count tumor in the present patient, the patient died of the disease 15 months after tumor resection operation.…”

“…[2][3][4] We report a case of malignant GIST-type tumor of the greater omentum in a patient who had local recurrence and multiple liver metastases shortly after operation. We also review the literature.…”

Omental Leiomyoma in a Male Adult Horse

“…5,26,28 Furthermore, GISTs deriving from the omentum have been detected in humans. 8,9,16,18 However, the cellular origin of these so-called extragastrointestinal stromal tumors (EGISTs) is not known, and the occurrence of EGISTs is still discussed controversially. 1 One study could find KIT-positive mesenchymal cells in the normal human omentum; 24 in another study, most cases of EGISTs were re-diagnosed as metastases of normal GISTs or as GISTs that have arisen from the outer muscle coat of the gastrointestinal tract and lost their contact due to an extensive extramural growth pattern.…”