**4. Histopathology**

The three main histopathologic subtypes of GIST are spindle cell, epithelioid, and mixed types, with spindle cell type being the most common constituting about 70% of GISTs, while the other two subtypes, epithelioid and mixed, are less common, accounting for 20 and 10% of all GISTS, respectively [6]. Epithelioid GIST is commonly observed in the stomach and omentum [6]. About 95% of GIST will be immunohistochemical positive for CD117(c-KIT) [4]. Epithelioid type has a weaker KIT positivity than spindle cell type [37]. In addition, 70–90% are positive for CD34, 20–30% for actin, 8–10% for S-100, and 2–4% for desmin [38]. DOG1 marker, also known as ANO1, has more than 95% sensitivity for GIST and is expressed in more than 35% of GISTs negative for c-kit [39, 40].
