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: Medicine
[{'content': "McCallum's patch is diagnostic of : \nSelect and explain. \nA. Infective endocarditis, B. Rheumatic endocarditis, C. Myocardial infarction, D. Tetralogy of fallout (TOF)", 'role': 'user'}, {'content': "Answer: B \nExplanation: Answer is B (Rheumatic endocarditis) Mac Callum's Patch is a fi'ature of mural endocarditis in Rheumatic fever. Mac Callum's Patch 'Mc.Callum's patch' is the region of endocardial surface in the posterior walldeg of left atrium just above the posterior leaflet of mitral valve. It appears as a 'map like' area of thickened, roughened, and wrinkled pa of endocardium. It is perhaps produced as a result of regurgitant jets.", 'role': 'assistant'}]