This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'Which of the following markers is specific for gastro-intestinal stomal tumor (GIST) - \nSelect and explain. \nA. CD 117, B. CD 34, C. CD 23, D. S-100', 'role': 'user'}, {'content': 'Answer: A \nExplanation: lmmunohistochemistry o Following markers are present in GISTs: i) CD 117 (c kit) -->95% ii) CD 34 --> 70% iii) Smooth muscle actin 5% CD 117 (c kit) is considered the most specific marker o CD 117 (c kit) immunoreactivity is the best defining feature of GISTs distinguishing them from true smooth muscle tumors (leiomyoma) and tumors arising from neural crest. o 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. REF: ROBBINS pathology 10th edition', 'role': 'assistant'}]