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': '“Aschoff bodies” are seen in: \nSelect and explain. \nA. Rheumatoid arthritis, B. Rheumatic fever, C. Bacterial endocarditis, D. Marantic endocarditis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Rheumatic fever (RF)\nMorphology\n\nDuring acute RF, focal inflammatory lesions are found in various tissues.\nDistinctive lesions occur in the heart, called Aschoff bodies, which consist of foci of lymphocytes\xa0(primarily T cells), occasional plasma cells, and plump activated macrophages called Anitschkow cells\xa0(Pathognomonic for RF).\nThese macrophages have abundant cytoplasm and central round-to ovoid nuclei in which the chromatin is\xa0disposed in a central, slender, wavy ribbon (hence the designation "caterpillar cells"), and may become\xa0multinucleated.\nDuring acute RF,\xa0diffuse inflammation and Aschoff bodies may be found in any of the three layers of the\xa0heart, causing pericarditis, myocarditis, or endocarditis (pancarditis).\nInflammation of the endocardium and the left sided valves typically results in fibrinoid necrosis within\xa0the cusps or along the tendinous cords.\nOverlying these necrotic foci are small (1 - to 2- mm) vegetations, called verrucae,\xa0along the\xa0lines of closure.\nSubendocardial lesions, perhaps exacerbated by regurgitant jets, may induce irregular thickenings called\xa0MacCallum plaques, usually in the left atrium.\n\nChronic Rheumatic Heart Disease\n\nThe changes of the mitral valve in are:\n\n\nLeaflet thickening\nCommissural fusion\nShortening, thickening and fusion of the tendinous cords\n\n\nIn chronic disease, the mitral valve is virtually always involved\nThe mitral valve is affected alone in 65% to 70% of cases, and along with the aortic valve in another 25%\xa0of cases.\nFibrous bridging across the valvular commissures and calcification create "fish mouth" or “buttonhole”\xa0stenoses.', 'role': 'assistant'}]