Vasculitis

Pathophysiology

• Inflammation of blood vessel walls leads to:
  • Vessel wall thickening and narrowing of lumen
  • Weakening of vessel walls, potentially causing aneurysms
  • Tissue ischaemia due to compromised blood flow
  • Vessel occlusion from thrombosis
• Immune-mediated mechanisms often involved:
  • Antineutrophil cytoplasmic antibodies (ANCA)
  • Immune complex deposition
  • T-cell-mediated inflammation

Demographics

• Incidence varies by specific type of vasculitis
• Generally affects all age groups, but some types more common in certain demographics:
  • Giant cell arteritis: typically affects those >50 years
  • Kawasaki disease: primarily affects children <5 years
  • Takayasu arteritis: more common in young women
• Some types show geographical or ethnic predilections:
  • Behçet's disease: more prevalent along the ancient Silk Road

Diagnosis

• Clinical presentation varies widely depending on affected vessels and organs
• Laboratory tests:
  • Elevated inflammatory markers (ESR, CRP)
  • ANCA testing for certain types (e.g. granulomatosis with polyangiitis)
  • Complement levels
• Tissue biopsy: often considered the gold standard for diagnosis
• Imaging plays a crucial role in diagnosis and monitoring

Imaging

• Modalities used:
  • Ultrasound: for superficial vessels and temporal arteries
  • CT angiography: excellent for medium and large vessel evaluation
  • MR angiography: useful for follow-up and reducing radiation exposure
  • PET-CT: can detect early inflammatory changes and assess disease activity
• Common findings:
  • Vessel wall thickening and enhancement
  • Luminal narrowing or occlusion
  • Aneurysm formation
  • Vessel wall calcification in chronic cases
  • Surrounding soft tissue inflammation
• Specific patterns:
  • Large vessel vasculitis: aorta and major branch involvement
  • Medium vessel vasculitis: renal, hepatic, and mesenteric artery involvement
  • Small vessel vasculitis: often manifests as end-organ damage

Treatment

• Goals: suppress inflammation, prevent organ damage, and manage complications
• Corticosteroids: mainstay of initial treatment for most types
• Immunosuppressive agents:
  • Cyclophosphamide, methotrexate, azathioprine
  • Rituximab for ANCA-associated vasculitis
• Biological agents:
  • TNF inhibitors (e.g. infliximab) for refractory cases
  • Tocilizumab for giant cell arteritis
• Antiplatelet therapy: to reduce risk of thrombotic complications
• Surgical intervention:
  • Aneurysm repair
  • Revascularisation for severe stenosis
• Regular imaging follow-up to assess treatment response and detect complications

Differential diagnosis