Vasculitis - antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis
Description
- Pauci-immune, necrotising small-vessel vasculitis (capillaries, venules, arterioles, small arteries)
- Three entities - Chapel Hill definitions
| Defining feature | ANCA | Renal | |
|---|---|---|---|
| GPA (Wegener's) | Necrotising GRANULOMATOUS inflammation of the respiratory tract + small-vessel vasculitis | PR3 (c-ANCA), ~90% positive | Common necrotising GN |
| MPA | Necrotising small-vessel vasculitis, NO granulomas | MPO (p-ANCA), ~70% positive | Very common necrotising GN; frequent pulmonary capillaritis |
| EGPA (Churg-Strauss) | Eosinophil-rich granulomatous inflammation + asthma + eosinophilia | MPO, only ~50% positive | Variable, ~50%, usually milder |
- *ANCA specificity (PR3 vs MPO) predicts phenotype, treatment response and relapse risk better than the clinical label*
- PR3: granulomatous, upper airway, relapsing, better rituximab response
- MPO: renal-limited, fibrotic, less relapsing, more ESKD
EGPA has two phenotypes
- ANCA-positive (~40%) - vasculitic: glomerulonephritis, mononeuritis multiplex, purpura, alveolar haemorrhage
- ANCA-negative (~60%) - eosinophilic: cardiomyopathy, lung infiltrates, GI disease
- *Cardiac involvement is the leading cause of death in EGPA and clusters with ANCA-negative disease*
6 more sections, plus exam facts
Premium unlocks every note across every specialty, and the full exam fact library behind it.
Get premium access