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': 'The most specific immunohistochemical marker to rule out invasive ductal carcinoma would be? \nSelect and explain. \nA. Ki-67, B. p 63, C. Desmin, D. HER 2 / neu', 'role': 'user'}, {'content': 'Answer: B \nExplanation: p63 is a marker for myoepithelial cells. When neoplastic cells are identified outside the myoepithelial layer around the ducts, the lesion is said to be invasive. So p63 is most specific marker.', 'role': 'assistant'}]