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: Biochemistry
[{'content': 'A 56 year old Chronic smoker, mass in bronchus resected. Most useful immunohistochemical marker to make a proper diagnosis would be ? \nSelect and explain. \nA. Cytokeratin, B. Vimentin, C. Epithelial membrane cadherin, D. Leucocyte common antigen', 'role': 'user'}, {'content': "Answer: A \nExplanation: o Mass in bronchus in a old chronic smoker suggest bronchogenic carcinoma. The marker of carcinoma, on immunohistochemistry, is cytokeratin.o Other epithelial markers for carcinoma are :-Epithelial membrane antigen (EMA) :- Breast, lung and Kidney's adenocarcinoma.Carcino-embryonic antigen :- Carcinomas of GIT, pancreas, lung, breast, uterus and ovary.", 'role': 'assistant'}]