Dilated cardiomyopathy shows which histologic features?

• A. Normal myocardium with no structural changes
• B. Lymphocytic infiltration with myocardial necrosis
• C. Extensive granulomatous inflammation
• D. Nonspecific abnormalities including variations in myocyte size, myocyte vacuolization, fibrosis and fat replacement

Answer: (D)

Dilated cardiomyopathy shows nonspecific structural remodeling of the heart muscle rather than a single distinctive lesion. The tissue often reveals variations in myocyte size, myocyte vacuolization, and fibrous replacement in the interstitium, sometimes with fat infiltration. This pattern reflects chronic myocyte injury and remodeling associated with dilation and systolic dysfunction.

This differs from conditions like viral myocarditis, which would show lymphocytic infiltration with myocyte necrosis, or granulomatous diseases such as sarcoidosis, which feature granulomas. A normal-appearing myocardium would not fit the remodeling seen in dilated cardiomyopathy.