Rheumatic Heart Disease (RHD): High-Yield Pathology
Acute Rheumatic Fever (ARF) is a hypersensitivity reaction (Type II) that occurs following group A beta-hemolytic streptococcal (Streptococcus pyogenes) pharyngitis. It is a multisystem disease that can lead to chronic Rheumatic Heart Disease.
1. Diagnostic Criteria (Jones Criteria)
To diagnose ARF, you need evidence of prior GAS infection plus either 2 major or 1 major + 2 minor criteria:
- Major Criteria (JONES):
- J – Joints (migratory polyarthritis)
- O – Carditis (pancarditis: endo-, myo-, pericarditis)
- N – Nodules (subcutaneous)
- E – Erythema marginatum (rash)
- S – Sydenham chorea
2. Pathological Hallmarks
| Pathological Finding | Description |
|---|---|
| Aschoff bodies | Granulomatous structures with central fibrinoid necrosis and surrounding lymphocytes/plasma cells. |
| Anitschkow cells | Pathognomonic “caterpillar-shaped” nuclei seen within Aschoff bodies. |
3. Chronic Complications
Clinical Core: Chronic RHD is the most common cause of mitral stenosis. It involves thickening of the valve leaflets and commissural fusion, often resulting in a “fish-mouth” or “buttonhole” appearance.
- Valve Involvement: The mitral valve is most commonly affected (>95%), followed by the aortic valve.
- MacCallum plaques: Irregular thickenings on the left atrial endocardium caused by regurgitant jets.
- Prevention: Prompt treatment of streptococcal pharyngitis with penicillin is the gold standard to prevent ARF and subsequent RHD.