EGIST of the greater omentum - case study and review of literature.

The development of immunohistochemical methods has outlined a particular group of tumors, with very specific features and treatment, originating in the Cajal cells of the muscularis propria or related stem cell-like precursors present in the wall of the digestive tract called gastrointestinal stromal tumors (GISTs). A sub-segment with similar features may develop outside the digestive tract, namely extra-gastrointestinal stromal tumors (EGISTs). From the small category of EGISTs, we report on a case of a primary epithelioid EGIST of the greater omentum, which is seldom reported in literature. The tumor was diagnosed in a man with non-specific symptoms who presented for abdominal enlargement. The tumor was characterized and there was a preoperative suspicion of a non-digestive tumor located in the greater omentum. The tumor was surgically removed showing no contact with adjacent organs. Immunohistochemical examination was consistent with a primary EGIST of the greater omentum. Treatment with Imatinib mesylate was started and at two-year follow-up, the patient is disease free. The case raises problems regarding pathogenesis, immunohistochemical features, behavior, evolution and prognosis of omental EGIST, for which no significant or conflicting data are available in the literature.