A 70-year-old woman dies following a 3-week illness of progressive cardiac failure. At autopsy, the heart weighs 680 g (normal ~350 g). The left ventricular wall is dilated and thinned rather than hypertrophied. Microscopically, there is interstitial fibrosis, myocyte hypertrophy with large nuclei, and scattered areas of replacement fibrosis without significant coronary atherosclerosis. Which of the following diagnoses best fits this pathological pattern?

• A Dilated cardiomyopathy ✓
• B Hypertensive hypertrophic cardiomyopathy
• C Hypertrophic obstructive cardiomyopathy
• D Restrictive cardiomyopathy due to amyloid

Explanation

Dilated cardiomyopathy (DCM) is characterized by biventricular dilation and systolic dysfunction, with a heavy, floppy heart showing thinned ventricular walls and four-chamber dilation on gross pathology. Microscopically, myocyte hypertrophy, nuclear enlargement (reactive atypia), interstitial fibrosis, and replacement fibrosis are seen without significant coronary disease. Hypertensive cardiomyopathy shows concentric LV hypertrophy (thickened walls); hypertrophic cardiomyopathy shows asymmetric septal hypertrophy with myofiber disarray; amyloid restrictive cardiomyopathy shows apple-green birefringent deposits.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.