This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Which of the following markers is specific for Gastro intestinal stromal tumors (GIST)? \nSelect and explain. \nA. CD 117, B. CD 34, C. CD 23, D. S-100', 'role': 'user'}, {'content': 'Answer: A \nExplanation: CD 117 is most specific marker for Gastrolintestinal stromal tumor, than CD 34. GIST has a universal expression of CD117. It can also be present in fibroblastic and endothelail tumors. Ref: M. Wasif Saif (2010), Chapter "Gastrointestinal Stromal Tumors", In the book, "Gastrointestinal Malignancies", Volume 1, Issue 1, USA, Page 152; Robbin\'s Basic Pathology, 7th Edition, Page 826; Oncology: An Evidence Based Approach, (2006), Pages 413-14; Sternberg\'s-Diagnostic Surgical Pathology, 4th Edition, Page 1590', 'role': 'assistant'}]