Definition:

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the GI tract, arising from the interstitial cells of Cajal, or their precursor stem cells. GISTs account for about 80% of gastrointestinal sarcomas, with a mean annual incidence of 10-15 per million. Nearly 50-70% of the clinically apparent tumors arise in the stomach, 20-30% arise in the small intestine, 5-15% in the large intestine, and less than 5% in other locations. The genetic basis of GIST growth is a mutation of the KIT or PDGFRA gene leading to constitutional activation of receptor tyrosine kinases, which is the driving force behind tumor development.