KIT and gastrointestinal stromal tumor: The predominant localization of GISTs seems to be the stomach (60 %) and small intestine (30–20 %), but GISTs may develop in the colorectum, esophagus, and, rarely, in the mesentery, omentum, or retroperitoneum (extragastrointestinal GIST), where KIT-positive mesenchymal cells are found.