Vasculitides
MRCS Part A & B — Comprehensive Study Notes
Overview & Classification of Vasculitides
Vasculitis is inflammation of blood vessels. Classification by vessel size helps organise the differential diagnosis and predict clinical manifestations. The Chapel Hill Consensus Conference (CHCC 2012) classification system is the gold standard.
Chapel Hill Consensus Conference Classification (CHCC 2012)
| Vessel Size | Vasculitis Type | Key Features | ANCA Status |
|---|---|---|---|
| Large Vessel | Giant Cell Arteritis (GCA/Temporal Arteritis) | Granulomatous inflammation of elastic arteries; extracranial (temporal artery, aorta, branch arteries); age >50; visual loss risk | Negative |
| Takayasu’s Arteritis | Granulomatous inflammation of aorta and main branches; young Asian women; pulseless disease risk | Negative | |
| Medium Vessel | Polyarteritis Nodosa (PAN) | Segmental necrotising inflammation; microaneurysms on angiography; NO glomerulonephritis (distinctive); HBV association 30% | Negative |
| Kawasaki Disease | Medium vessel vasculitis; children; coronary artery involvement; fever, rash, mucosal changes | Negative | |
| Small Vessel — ANCA-Associated | GPA (Granulomatosis with Polyangiitis/Wegener’s) | Necrotising granulomatous vasculitis; upper respiratory (sinusitis, epistaxis, saddle-nose deformity), lung (cavitary lesions, haemoptysis), kidney (RPGN) | c-ANCA/PR3 (90% systemic) |
| MPA (Microscopic Polyangiitis) | Necrotising non-granulomatous vasculitis; pauci-immune RPGN; pulmonary capillaritis (DAH); NO granulomas, NO ENT | p-ANCA/MPO (75%) | |
| EGPA (Eosinophilic GPA/Churg-Strauss) | Necrotising vasculitis with eosinophil infiltration; asthma (cardinal feature in all cases), peripheral eosinophilia, cardiac involvement, pulmonary infiltrates | p-ANCA/MPO (40–50%) | |
| Small Vessel — Immune Complex | IgA Vasculitis (IgAV/Henoch-Schönlein Purpura) | IgA-dominant immune complex deposition in kidneys, skin, GI; palpable purpura; arthritis; abdominal pain; glomerulonephritis | Negative |
| Cryoglobulinaemic Vasculitis | Immune complex deposition; HCV association; palpable purpura, peripheral neuropathy, glomerulonephritis | Negative | |
| Anti-GBM Disease (Goodpasture’s) | Linear IgG deposit on basement membrane; pulmonary-renal syndrome; diffuse alveolar haemorrhage; crescentic GN | Negative | |
| Variable Vessel | Behçet’s Disease, Cogan’s Syndrome | Recurrent oral/genital aphthous ulcers; eye involvement; thrombosis (venous), aneurysms | Negative |
Diagnostic Approach to Suspected Vasculitis
History & Exam: Constitutional symptoms (fever, malaise, weight loss, night sweats), organ-specific manifestations (skin, respiratory, renal, neurological), vascular claudication, pulses. Inflammatory markers: ESR (usually >50 mm/hr in active disease, but may be normal in 20–30%), CRP, FBC (anaemia, thrombocytosis, neutrophilia), U&E (renal dysfunction), LFT, urinalysis (proteinuria, haematuria, RBC casts → glomerulonephritis). ANCA testing: c-ANCA (PR3 = GPA), p-ANCA (MPO = MPA/EGPA). Imaging: CXR (pulmonary infiltrates, cavitations), HRCT chest (diffuse alveolar haemorrhage, nodules), imaging of affected organs. Biopsy: Gold standard for diagnosis — tissue inflammation, immunofluorescence pattern (ANCA-associated = pauci-immune; immune complex = granular deposits). Treatment framework: Induction phase (high-dose corticosteroids ± immunosuppressive agents) → achieve remission → remission maintenance (lower-dose corticosteroids + steroid-sparing agents) → monitoring (clinical activity, inflammatory markers, organ function).