Gastrointestinal stromal tumors (GIST for its acronym in English) are the most common mesenchymal neoplasm in the gastrointestinal tract, and perhaps the most common sarcoma of all. They originate from the interstitial cells of Cajal or their precursors, these cells have characteristics of smooth muscle cells, fibroblasts and neurons. GIST’s are typically positive for the KIT tyrosine receptor by immunohistochemistry. At the genomic level, mutations in the KIT gene or in the gene receptor tyrosine kinase PDGFR are the characteristics that distinguish this type of tumor. KIT and PDGFRα are mutated in approximately 85% and 5% respectively.