This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Pathology
[{'content': 'All are true about GIST EXCEPT? \nSelect and explain. \nA. Most common mesenchymal tumor of GIT, B. C-kit (CD 117) positive, C. Originate from interstitial cells of Cajal, D. Majority seen in duodenum', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref: Robbins Pathology, 9th ed. pg. 775-76* Majority of gastrointestinal stromal tumors originate from stomach. The cell of origin is interstitial cell of Cajal which are present in muscularispropria.* The useful marker is c-kit (CD 117) detectable in 95% of patients.* PET scan is the imaging modality of choice* Treatment is tyrosine kinase inhibitors like imatinib mesylate.', 'role': 'assistant'}]