A 52-year-old Indian man presents with sudden-onset chest pain, acute myocardial infarction on ECG, and coronary angiography shows no atherosclerotic disease. Histology of the coronary artery reveals granulomatous inflammation with giant cells and medial necrosis. Which vasculitis syndrome best explains this presentation?

Explanation

## Giant Cell (Temporal) Arteritis: Granulomatous Vasculitis in the Older Adult ### Clinical Presentation & Pathology **Key Point:** Giant Cell Arteritis (GCA) is a **large-to-medium vessel granulomatous vasculitis** that predominantly affects individuals **>50 years of age**, involving the temporal artery, carotid branches, and — critically — the **coronary arteries**, causing acute MI without atherosclerosis. ### Distinguishing Features: Why GCA Over Takayasu? | Feature | Giant Cell Arteritis | Takayasu Arteritis | Polyarteritis Nodosa | Behçet Disease | | --- | --- | --- | --- | --- | | **Age of onset** | **>50 years (elderly)** | 10–40 years (young) | 40–60 years | 20–40 years | | **Vessel size** | Medium–large (temporal, coronary, aorta) | Large (aorta, proximal branches) | Small–medium (renal, coronary) | Small–medium (veins, arteries) | | **Granulomatous inflammation** | **Yes (with giant cells)** | Yes (with giant cells) | No (fibrinoid necrosis) | No (lymphocytic infiltrate) | | **Medial necrosis** | **Yes** | Yes | Yes (fibrinoid) | No | | **Coronary involvement → MI** | Yes (direct arteritis) | Ostial stenosis (less direct) | Occasional | Rare | | **Geography** | Western countries; also Asia | Asia, Latin America | Worldwide | Mediterranean, Middle East, Asia | ### Pathological Hallmark **High-Yield:** GCA histology shows: 1. **Granulomatous inflammation** of the media with **Langhans-type giant cells** 2. **Medial necrosis** and disruption of the internal elastic lamina 3. Intimal hyperplasia → luminal narrowing → ischemia/infarction This is **identical** to the histology described in the stem: *granulomatous inflammation with giant cells and medial necrosis*. ### Why NOT Takayasu Arteritis? - Takayasu arteritis peaks at **10–40 years**; this patient is **52 years old**, which is above the typical range and falls squarely in the GCA demographic (>50 years). - Takayasu primarily causes **ostial stenosis** of the aorta and its major branches; direct coronary arteritis with the described histology is more characteristic of GCA. - GCA is the **most common systemic vasculitis in adults >50 years** (Robbins 10e, Ch 11). ### Clinical Pearl **Giant Cell Arteritis** can involve the coronary arteries directly, producing acute MI in the absence of atherosclerosis. The combination of: - Age >50 years - Granulomatous inflammation with giant cells - Medial necrosis - No atherosclerotic disease on angiography …is **pathognomonic for GCA** affecting the coronary circulation. **Mnemonic:** **GCA = Giant Coronary Attack** in the elderly — always suspect GCA when an older patient has MI with clean coronaries and granulomatous histology. [cite:Robbins 10e Ch 11; Harrison's Principles of Internal Medicine, 21e]