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': 'Sheela, a middle aged diabetic female presented with flank pain and fever. On U/S the kidney was irregular and showed fat density lesion with calculi. The diagnosis is most probably - \nSelect and explain. \nA. TB kidney, B. Xanthogranulomatous kidney, C. Chronic pyelonephritis, D. Renal abscess', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Xanthogranulomatous pyelonephritis\n\nXantho means lipid laden foam cells.\nXanthogranulomatous pyelonephritis is a variant of chronic pyelonephritis that characteristically presents in middle aged patients with a poorly functioning kidney (as in diabetic)\nOn histology there are areas of clear cells that are lipid laiden macrophages.\nThese areas of lipid laiden macrophage appear as fat density lesion on U/S.\nThis pyelonephritis is often accompanied by a calculus and proteus infection.', 'role': 'assistant'}]