This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rheumatic, Subject name: Medicine
Mccallum patch in rheumatic heart disease is seen in? 
Select and explain. 
A. Right atrium, B. Left atrium, C. Right ventricle, D. Left ventricle
B: Left atrium
Answer: B: Left atrium 
Explanation: Ans. (b) Left atriumRef: Robbins 8th edition, Chapter 11Mural endocardial lesions can be seen as MacCallum plaques in rheumatic heart disease. These plaques appear as map-like areas of thickened, roughened, and wrinkled part of the endocardium in the left atrium. Perhaps they are caused by regurgitant jets of blood flow, due to incompetence of the mitral valve