A 17-year-old high school student dies suddenly while playing basketball.Autopsy and histologic sections are given. What is the most likely diagnosis?
Sudden death in a young athlete is often linked to cardiac issues. Common causes include hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular cardiomyopathy (ARVC), or congenital coronary artery anomalies. HCM is the most common, characterized by left ventricular hypertrophy and myofibrillar disarray on histology. ARVC involves the right ventricle with fibrofatty replacement of myocardium. Another possibility is long QT syndrome or Wolff-Parkinson-White syndrome, but those are electrical issues without structural changes.
Given that histologic sections are mentioned, HCM would show the myofibrillar disarray. ARVC might show fibrofatty infiltration. If the other options aren't listed, I'll assume the correct answer is HCM. The core concept here is sudden cardiac death in athletes, with HCM being the leading cause. The key histological finding is myofibrillar disarray. Other options like ARVC or coronary anomalies are less likely if the histology shows specific features. Clinical pearl: HCM is a leading cause of sudden cardiac death in young athletes; family history and screening ECGs are important. Correct Answer: C. Hypertrophic Cardiomyopathy.
**Core Concept**
Sudden cardiac death in young athletes is most commonly caused by **hypertrophic cardiomyopathy (HCM)**, characterized by **asymmetric left ventricular hypertrophy** and **myofibrillar disarray** on histology. This condition is a leading cause of sudden cardiac death in individuals under 30.
**Why the Correct Answer is Right**
HCM results from mutations in sarcomeric proteins (e.g., **β-myosin heavy chain** or **troponin T**), leading to disorganized myocardial fibers and impaired relaxation. The histologic hallmark is **myofibrillar disarray**, which creates a substrate for arrhythmias. During exercise, the increased myocardial oxygen demand and outflow obstruction in HCM can trigger ventricular fibrillation, especially in undiagnosed cases.
**Why Each Wrong Option is Incorrect**
**Option A:** *Arrhythmogenic right ventricular cardiomyopathy (ARVC)* involves **fibrofatty replacement** of the right ventricle, not myofibrillar disarray.
**Option B:** *Marfan syndrome* causes **aortic root dilation** and mitral valve prolapse, but not histologic myocyte disarray.
**Option D:** *Wolff-Parkinson-White (WPW)* syndrome is an electrical conduction abnormality without structural myocardial changes.
**Clinical Pearl / High-Yield Fact**
**HCM is the most common cause of sudden cardiac death in young athletes.** Screening for family history, ECG abnormalities (e.g., deep T-wave inversions), and echocardiography are critical. Remember the **"septal spike"** on EKG and **"turbulent flow"** on auscultation as classic clues.
**Correct