Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors in the gastrointestinal tract. They arise from Cajal cells within the Auerbach's plexus in the muscularis propria. GISTs constitute approximately 1% of gastrointestinal tumors. It is estimated that approximately 700-1200 new cases are diagnosed in Poland annually, of which 140-400 are malignant. The most common location is the stomach.