This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rheumatic Fever, Subject name: Pathology
A 10-year-old boy, Pappu, died of acute rheumatic fever. All the following can be expected at autopsy, except: 
Select and explain. 
A. Aschoff's nodules, B. Anitschkow cells, C. McCallum patch, D. Fibrinous pericarditis
C: McCallum patch
Answer: C: McCallum patch 
Explanation: MacCallum patch/plaque is a feature of chronic rheumatic hea disease (RHD). During mitral regurgitation, where the regurgitant jet strikes back the atrial wall, results in endocardial thickening and it is called MacCallum patch or MacCallum plaques. They are described as "map-like areas of thickened, roughened, and wrinkled pa of the endocardium in the left atrium", usually associated with dilated left atrium.