[Gastrointesinal stromal tumors--clinical and morphological aspects].

Gastrointestinal Stromal Tumors (GISTs) are uncommon mesenchimal tumors that usually arise in the wall of the gastrointestinal tract. Although heterogenous in morphology, GISTs represent a group of tumors probably originating from the intestinal pacemaker cell, interstitial cell of Cajal. The tumour cell phenotype can be established only when histomorphology is coupled with immunostaining. They account for approximately 0.1% to 3% of all gastrointestinal neoplasms. GISTs arise anywhere along the GI tract, from the oesophagus to the rectum. Most tumors (70%) occur in the stomach and about 20-30% occur in the small intestine. A small percentage of GISTs arise elsewhere in the GI tract, omentum, or retroperitoneum. We describe four GISTs arising in stomach, small intestine, omentum and colon with their clinical and morphological presentation.