Marker specific for Gastrointestinal Stromal Tumor (GIST): September 2012

Ans. A i.e. CD117 Gastrointestinal stromal tumor (GIST) It is one of the most common mesenchymal tumorsof the gastrointestinal tract (1-3% of all gastrointestinal malignancies). They are typically defined as tumors whose behavior is driven by mutations in the Kit gene or PDGFRA gene, and may or may not stain positively for Kit. When GIST is suspected -- as opposed to other causes for similar tumors -- the pathologist can use immunohistochemistry (specific antibodies that stain the molecule CD117 -- see below). 95% of all GISTs are CD117-positive (other possible markers include CD34, DOG-1, desmin, and vimentin). Other cells that show CD117 positivity are mast cells