Which histologic finding is typical of viral myocarditis?

Which histologic finding is typical of viral myocarditis?

• A. Fibrous scar in the myocardium
• B. Inflammatory infiltrates within the myocardium
• C. Vegetations on valve leaflets with organisms
• D. Eosinophilic infiltration of the myocardium

Answer: (B)

Viral myocarditis classically shows inflammatory infiltrates within the myocardium accompanied by myocyte injury. The infiltrate is typically lymphocytic, reflecting a cell-mediated immune response to a viral infection, often with edema and focal necrosis of myocytes. This pattern distinguishes it from other myocardial conditions: a fibrous scar suggests a healed or fibrotic process rather than active viral inflammation; vegetations on valves with organisms point to infective endocarditis rather than primary myocarditis; eosinophilic infiltration points to eosinophilic myocarditis seen with hypersensitivity or parasitic infections. So the presence of inflammatory cells within the myocardium, especially lymphocytes, is the hallmark of viral myocarditis.

Viral myocarditis classically shows inflammatory infiltrates within the myocardium accompanied by myocyte injury. The infiltrate is typically lymphocytic, reflecting a cell-mediated immune response to a viral infection, often with edema and focal necrosis of myocytes. This pattern distinguishes it from other myocardial conditions: a fibrous scar suggests a healed or fibrotic process rather than active viral inflammation; vegetations on valves with organisms point to infective endocarditis rather than primary myocarditis; eosinophilic infiltration points to eosinophilic myocarditis seen with hypersensitivity or parasitic infections. So the presence of inflammatory cells within the myocardium, especially lymphocytes, is the hallmark of viral myocarditis.