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': 'All of the following are pathologic features of primary tuberculosis, EXCEPT: \nSelect and explain. \nA. Cavitation, B. Caseation, C. Calcification, D. Langerhans giant cell', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Primary TB is a form of disease that develops in a previously unexposed, and therefore unsensitized person. Secondary TB is the pattern of disease that arises in a previously sensitized host. Cavitation occurs in secondary TB. The caseous necrosis occurring in primary TB is conveed into a cavity in secondary TB. Ref: Robbins Pathologic Basis of Disease, 6th Edition, Pages 723-4', 'role': 'assistant'}]