This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pathology
Mac Callum plaques in rheumatic hea disease are 
Select and explain. 
A. Left atrium, B. Left ventricle, C. Right atrium, D. Right ventricle
A: Left atrium
Answer: A: Left atrium 
Explanation: Mac Callum's plaques is a condition featuring the thickening of left atrium's wall and its endocardial wall above the mitral valve due to fibrosis. It is one complication of chronic rheumatic hea disease. Other complications of chronic rheumatic hea disease are valvular effect (stenosis, insufficiency or can be both), valvular leaflets become thickened by fibrosis, frequent valvular calcification, cordae tendinae become thickened, shoened and fused. Robbins 9 th edition page 393