KIT and gastrointestinal stromal tumor: CD117 (c-KIT)-negative GISTs are usually non-conventional, have an epithelioid morphology, a myxoid stromal background, abundant mast cells, and are commonly located in E-GIST locations, such as the omentum, which harbors PDGF-a receptors mutation [29]. DOG1, which stands for Discovered On GIST-1, is a very sensitive and specific marker for GIST, which stains interstitial cells of Cajal in the GI tract [30].