Anatomic and Clinical Pathology

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the GI tract. These tumors derive from Cajal cells or their precursors. The oncogenic drivers are tyrosine kinase enzymes (KIT) and, to a lesser degree, platelet- derived growth factor receptor alpha (PDGFRA), both of which become constitutively activated following certain primary mutations. These mutations are mostly in the c- KIT gene and rarely in PDGFRA.