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
GIST associated marker is? 
Select and explain. 
A. CD 117, B. CD 34, C. CD 23, D. S-100
A: CD 117
Answer: A: CD 117 
Explanation: Ans. is 'a' i.e., CD 117 * The most useful marker of GIST is C-kit (CD-I 17). Other markers are CD 34, smooth muscle actin and vimentin.* Although CD 117 (c kit) is considered the most specific marker for GIST, it is not pathognomonic of GIST as other tumors may also express CD 117. These tumors include mast cell tumor, germ cell tumors (seminomas), leukemias, malignant melanoma, angiolipomas, and some sarcomas.