A 15 year old boy died suddenly while playing in the field. On autopsy, fibrofatty replacement of right ventricular myocardium is seen. Most likely diagnosis is:
**Core Concept**
The sudden death of a 15-year-old boy due to fibrofatty replacement of the right ventricular myocardium suggests a condition that affects the heart muscle, leading to its replacement with fibrous and fatty tissue. This pathologic change is characteristic of a specific cardiomyopathy.
**Why the Correct Answer is Right**
The correct diagnosis is arrhythmogenic right ventricular cardiomyopathy (ARVC), also known as arrhythmogenic right ventricular dysplasia (ARVD). ARVC is a heart condition characterized by fibrofatty replacement of the right ventricular myocardium, leading to abnormal heart rhythms and potentially sudden cardiac death. The disease is caused by mutations in genes that encode desmosomal proteins, which are crucial for maintaining the structural integrity of cardiac muscle cells. As the disease progresses, the fibrofatty tissue replaces the normal myocardium, disrupting the electrical conduction system of the heart and increasing the risk of life-threatening arrhythmias.
**Why Each Wrong Option is Incorrect**
* **Option A:** Hypertrophic cardiomyopathy (HCM) is a different cardiomyopathy characterized by thickening of the heart muscle, which can lead to obstruction of blood flow and sudden cardiac death. However, HCM typically affects the left ventricle, not the right ventricle.
* **Option B:** Dilated cardiomyopathy (DCM) is a condition where the heart muscle becomes weak and the heart chambers enlarge, leading to poor heart function. While DCM can cause sudden cardiac death, it is not characterized by fibrofatty replacement of the myocardium.
* **Option C:** Restrictive cardiomyopathy (RCM) is a condition where the heart muscle becomes stiff, making it difficult for the heart to fill with blood during diastole. RCM can cause heart failure symptoms, but it is not associated with fibrofatty replacement of the myocardium.
**Clinical Pearl / High-Yield Fact**
ARVC is a leading cause of sudden cardiac death in young athletes, and it is often asymptomatic until the time of sudden cardiac arrest. A thorough family history and genetic testing are essential in diagnosing ARVC, as it has a strong familial component.
**Correct Answer:** C.