Which histopathologic feature best distinguishes degenerative (calcific) aortic stenosis from rheumatic aortic stenosis?

Question

Accepted Answer

B. Calcium deposition confined to the nodules at the base of the cusps with intact commissures. ## Distinguishing Degenerative from Rheumatic Aortic Stenosis

### Pathologic Mechanisms

**Key Point:** Degenerative (calcific) aortic stenosis results from mechanical wear and tear leading to calcium deposition in the aortic cusps, while rheumatic aortic stenosis is an inflammatory sequela of acute rheumatic fever causing commissural fusion and fibrosis.

### Histopathologic Comparison Table

| Feature | Degenerative (Calcific) AS | Rheumatic AS |
| --- | --- | --- |
| **Commissures** | Intact, not fused | Fused |
| **Calcium location** | Nodules at cusp base (fibrosa side) | May be present but not primary |
| **Inflammation** | Minimal, degenerative | Prominent: fibrinoid necrosis, lymphocytes |
| **Valve substance** | Fibrosis with calcification | Inflammatory infiltrate + fibrosis |
| **Leaflet mobility** | Reduced (stiffening) | Reduced (retraction + fusion) |
| **Associated lesions** | Aortic regurgitation (late) | Mitral stenosis (often concurrent) |

### Clinical Pearl

**Clinical Pearl:** On gross inspection, degenerative AS shows **nodular calcification at the base of the cusps with preserved commissures**, whereas rheumatic AS shows **commissural fusion with a narrowed orifice**. Microscopically, degenerative disease lacks the inflammatory infiltrate characteristic of rheumatic disease.

### High-Yield Discriminator

**High-Yield:** **Intact commissures with nodular calcification = Degenerative AS.** **Fused commissures = Rheumatic AS.** This distinction is crucial because rheumatic AS is almost always accompanied by mitral valve disease (especially mitral stenosis), whereas degenerative AS is isolated to the aortic valve.

### Mnemonic

**Mnemonic:** **DECAL** = **DE**generative **CAL**cific (nodules, intact commissures); **RHEUM** = **RHEUM**atic (fused commissures, inflammation).

[cite:Robbins 10e Ch 12]

![Valvular Heart Disease diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/2932.webp)

Answer

A. Fibrinoid necrosis and inflammatory infiltrate in the valve substance

Answer

C. Thickening and retraction of the chordae tendinae

Answer

D. Commissural fusion of valve leaflets

Which histopathologic feature best distinguishes degenerative (calcific) aortic stenosis from rheumatic aortic stenosis?

Explanation

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Distinguishing Degenerative from Rheumatic Aortic Stenosis

Pathologic Mechanisms

Histopathologic Comparison Table

Clinical Pearl

High-Yield Discriminator

Mnemonic

Feature	Degenerative (Calcific) AS	Rheumatic AS
Commissures	Intact, not fused	Fused
Calcium location	Nodules at cusp base (fibrosa side)	May be present but not primary
Inflammation	Minimal, degenerative	Prominent: fibrinoid necrosis, lymphocytes
Valve substance	Fibrosis with calcification	Inflammatory infiltrate + fibrosis
Leaflet mobility	Reduced (stiffening)	Reduced (retraction + fusion)
Associated lesions	Aortic regurgitation (late)	Mitral stenosis (often concurrent)