• Dec 12, 2025 mcqs pathology immunohistochemistry epithelial origin, characteristic of carcinomas. 3. Diagnostic Application Question: Which immunohistochemical marker is most useful for distinguishing between primary lung adenocarcinoma and metastatic colorectal carcinoma? a) TTF-1 b) CK20 c) CDX2 d) All of the above Ans By Dr. Cathy Rowe
