Cardiac Pathology — MCQs

Question 1: What type of cardiomyopathy is characterized by this arrangement of myofibrils?

• A. Dilated cardiomyopathy
• B. Constrictive cardiomyopathy
• C. Fibroelastic cardiomyopathy
• D. Hypertrophic cardiomyopathy (Correct Answer)

Explanation: ***Hypertrophic cardiomyopathy*** - **Myofibrillar disarray** (chaotic, disorganized arrangement of cardiac myofibers) is the **pathognomonic histological hallmark** of hypertrophic cardiomyopathy. - This characteristic **disorganized pattern** distinguishes HCM from other cardiomyopathies and is essential for definitive diagnosis. *Dilated cardiomyopathy* - Shows **hypertrophy** and **fibrosis** but maintains **normal myofibrillar organization** without the characteristic disarray. - Histologically characterized by **enlarged chambers** with **thinned walls**, not disorganized myofibrils. *Constrictive cardiomyopathy* - This is not a recognized form of **primary cardiomyopathy** but rather refers to **constrictive pericarditis**. - **Pericardial thickening** and **calcification** are the main features, not myofibrillar changes. *Fibroelastic cardiomyopathy* - Also known as **endomyocardial fibrosis**, characterized by **subendocardial fibrosis** and **thickening**. - Shows **organized fibrotic tissue** deposition rather than **myofibrillar disarray** pattern.