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: Surgery
[{'content': 'True about anaplastic thyroid carcinoma: \nSelect and explain. \nA. Common in elderly, B. Well encapsulated, C. Will not invade surrounding structures, D. All', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans is A (Common in elderly) About option \'e\' Schwaz writes: "On gross inspection, anaplastic tumors are firm and whitish in appearance. Microscopically, sheets of cells with marked heterogeneity are seen. Cells may be spindle-shaped, polygonal, or large, multinucleated cells. Foci of more differentiated thyroid tumors, either follicular or papillary, may be seen, suggesting that anaplastic tumors arise from more well-differentiated tumors."', 'role': 'assistant'}]