Primary omental gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) represent the majority of primary non-epithelial neoplasms of the digestive tract, most frequently expressing the KIT protein detected by immunohistochemical staining for the CD117 antigen. Extragastrointestinal stromal tumors (EGISTs), neoplasms with immunohistological features overlapping those of GISTs, are found in the abdomen outside of the gastrointestinal tract with no connection to the gastric or intestinal wall. The present report presents the clinical, macroscopic and immunohistological features of an EGIST arising in the greater omentum of a 63-year-old woman, and discusses the clinical behavior and prognostic factors of such lesions in comparison to their gastrointestinal counterparts.