Vasculitis

Definition
Vasculitis is a group of disorders characterised by inflammation of blood vessel walls, which can lead to vessel narrowing, occlusion, aneurysm formation, or rupture. The result is impaired blood flow and tissue/organ damage. It can affect any vessel size and any organ system.

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Classification (by vessel size)

A. Large-vessel vasculitis

• Giant cell arteritis (temporal arteritis) – affects extracranial branches of the carotid artery; common in elderly

• Takayasu arteritis – affects aorta and its branches; common in young women

B. Medium-vessel vasculitis

• Polyarteritis nodosa (PAN) – systemic necrotising vasculitis; spares lungs

• Kawasaki disease – acute, self-limited vasculitis in children; can cause coronary artery aneurysms

C. Small-vessel vasculitis

• ANCA-associated vasculitis

  • Granulomatosis with polyangiitis (GPA, formerly Wegener’s)

  • Microscopic polyangiitis (MPA)

  • Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg–Strauss)

• Immune complex–mediated

  • IgA vasculitis (Henoch–Schönlein purpura)

  • Cryoglobulinaemic vasculitis

  • Hypocomplementaemic urticarial vasculitis

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Causes

• Primary (idiopathic) – most common, autoimmune origin

• Secondary – due to underlying cause such as:

  • Infections (hepatitis B/C, HIV)

  • Drugs (antibiotics, allopurinol, hydralazine)

  • Autoimmune diseases (SLE, rheumatoid arthritis)

  • Malignancies

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Pathophysiology

• Immune-mediated vessel wall inflammation (via immune complex deposition, ANCA antibodies, or direct autoimmune attack)

• Leads to vessel wall damage, fibrinoid necrosis, luminal narrowing, thrombosis, and ischaemia of downstream tissues

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General Clinical Features
Symptoms depend on vessel size, distribution, and affected organs, but systemic features are common:

• Fever

• Fatigue, malaise

• Weight loss

• Myalgia and arthralgia

• Night sweats

Organ-specific features

• Skin: palpable purpura, ulcers, livedo reticularis

• Nervous system: peripheral neuropathy, mononeuritis multiplex

• Kidneys: haematuria, proteinuria, renal failure

• Lungs: cough, haemoptysis, dyspnoea

• GI tract: abdominal pain, bleeding

• Eyes: visual disturbances (especially in giant cell arteritis)

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Diagnosis

• Laboratory tests:

  • Raised ESR and CRP

  • ANCA testing (c-ANCA in GPA, p-ANCA in MPA/EGPA)

  • ANA, complement levels, cryoglobulins, hepatitis serology

• Urinalysis: detect haematuria, proteinuria

• Imaging:

  • Ultrasound or MRI/CT angiography for vessel assessment

  • PET-CT for large vessel inflammation

• Biopsy: gold standard for diagnosis; shows vessel wall inflammation and necrosis

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Treatment
Treatment depends on type, severity, and underlying cause.

1. General principles

   • Treat underlying cause in secondary vasculitis (e.g., antivirals for hepatitis)

   • Induce remission with immunosuppressive therapy

   • Maintain remission with less toxic agents

2. Pharmacological

   • Corticosteroids (prednisolone, methylprednisolone) – first-line for most types

   • Immunosuppressants:

     • Cyclophosphamide – for severe, organ-threatening disease

     • Azathioprine, methotrexate, or mycophenolate – for maintenance

   • Biologic agents:

     • Rituximab – effective in ANCA-associated vasculitis

     • Tocilizumab – used in giant cell arteritis

   • Adjunctive:

     • Aspirin in large vessel vasculitis (to reduce thrombosis risk)

     • Prophylaxis against Pneumocystis jirovecii in patients on high-dose immunosuppression

3. Supportive

   • Blood pressure control

   • Renal function monitoring

   • Management of complications (e.g., ischaemia, infection)

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Prognosis

• Prognosis varies by type and extent of organ involvement

• Early diagnosis and treatment improve survival and reduce organ damage

• Relapse is common, especially in ANCA-associated vasculitis, requiring long-term follow-up