Primary tumours of the greater omentum are very rare. Ultrasound allows the detection and characterization of such lesions, but determination of their precise anatomical location is usually difficult by US. Computed tomography determines the omental origin of the tumour. Thus, when US reveals an abdominal tumour of unknown origin, the possibility of an omental tumour, although rare, must be kept in mind and CT should be performed.

Primary tumours of the greater omentum.

This article reviews the computed tomography imaging features of a variety of gastric tumors containing fatty tissue. Lipoma, angiolipoma, liposarcoma, and teratoma are described. Differential diagnosis includes primary and reactive lipomatosis, carcinoma engulfing the perivisceral fat thus mimicking differentiated liposarcoma, and mesenchymal gastric and peritoneal neoplasms.

Lipomatous tumors of the stomach: CT findings and differential diagnosis.

Gastrointestinal stromal tumors (GIST) are uncommon mesenchymal spindle-cell or epithelioid neoplasms, located mainly with higher frequency in the stomach and small bowel. GISTs represent the majority of primary non-epithelial neoplasms of the digestive tract, most frequently expressing the KIT protein a transmembrane tyrosine kinase receptor for stem cell factor. Extra-gastrointestinal stromal tumors tend to present In fewer than 5% of cases; they originate primarily from the mesentery, omentum or peritoneum. Furthermore, these extra-gastrointestinal tumors (EGIST) tend to be more common in patients over the age of 50 years. EGISTs are neoplasms with overlapping immunohistological features, occurring in the abdomen outside the gastrointestinal tract with no connection to the gastric or intestinal wall. We describe here a rare case of EGIST of the lesser omentum and report the clinical, macroscopic, immunohistological and radiological features of an EGIST arising in the lesser omentum of a 63-year old man. Clinical course and the prognostic factors of such lesions will also be discussed. EGISTs in the lesser omentum can grow slowly and remain silent despite a large tumor size. In most cases, a pre-operative diagnosis is not possible, and the patient undergoes a surgical operation for the generic diagnosis of abdominal mass. During the intervention it is important to achieve a complete removal of the mass and to examine every possible adhesion to the gastrointestinal wall.

https://journals.sagepub.com/doi/pdf/10.4081/rt.2012.e44

Extra-gastrointestinal stromal tumor of the omentum: a rare case report and review of the literature.

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.

Gastrointestinal stromal tumor of the lesser omentum: report of a case.

Two cases of liposarcoma of the stomach are described. At computed tomography (CT) the neoplasms showed features of an aggressive malignant tumor, with no fatty values within. We discuss the differential diagnosis of such lesions and conclude that, although rare, liposarcoma should be considered as a possible diagnosis when a large exophytic gastric mass is detected at CT.

Gastric liposarcoma: CT appearance

Three cases of primary leiomyosarcoma arising from the greater omentum are described. On CT the tumors were multilobulated, flat, and pancake-like, with enhancing solid and multicystic densities. The masses in all cases were located in the most anterior part of peritoneal cavity. These CT findings are useful in the preoperative diagnosis of omental leiomyosarcoma.

Kim Mj

Papers

Primary leiomyosarcoma of the greater omentum: CT findings.