This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Anatomy
[{'content': 'Oncocytic carcinoma arises from \nSelect and explain. \nA. Perivascular tissue, B. Glomerulus, C. Loop of henle, D. Collecting duct', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Refer Robbins 8/e p964, 9/ep953 Oncocytoma This is an epithelial neoplasm composed of large eosinophilic cells having small, round, benign-appearing nuclei that have large nucleoli. It is thought to arise from the intercalated cells of collecting ducts, and accounts for approximately 5% to 15% of renal neoplasms. Ultra-structurally the eosinophilic cells have numerous mitochondria. In gross appearance, the tumors are tan or mahogany brown, relatively homogeneous, and usually well encapsulated with a central scar in one-third of cases. However, they may achieve a large size (up to 12 cm in diameter). There are some familial cases in which these tumors are multicentric rather than solitary.', 'role': 'assistant'}]