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
Which of the following markers is specific for gastrointestinal stromal tumor (GIST): 
Select and explain. 
A. CD 117, B. CD 34, C. CD123, D. S-100
A: CD 117
Answer: A: CD 117 
Explanation: Ans. (a) CD 117(Ref: Robbins 9th/pg 775; 8th/pg 789)Most useful diagnostic marker is c-kit (CD117) detectable in 95% of the patients.