ANCA-associated vasculitis

Background

  • Vasculitis, in general, can be classified by the size of vessel affected and by associated with anti-neutrophil cytoplasmic antibody (ANCA)
  • ANCA-associated vasculitides share some common features (aside from presence of ANCA)
    • often involve small (occasionally medium) sized arteries
    • glomerulonephritis is a common feature
    • they usually respond well to immunosuppression
  • Rare diseases (combined incidence ~10-20/1000000)
  • The aetiology of these conditions is poorly understood (unlikely to be immune-complex mediated unlike pure small-artery vasculitis)

Classification 

  • ANCA-associated vasculitis
    • Necrotising vasculitis, with few or no immune deposits, predominantly affecting small vessels (i.e. capillaries, venules, arterioles and small arteries); associated with Myeloperoxidase (MPO-) ANCA or PR3-ANCA (although not all patients have ANCA i.e. ANCA-negative)
  • Granulomatosis with polyangitis (GPA) (previously Wegener’s granulomatosis)
    • Necrotising granulomatous inflammation usually involving the upper and lower respiratory tract; with necrotising vasculiti affecting small-medium vessels
      • Necrotising glomerulonephritis is common
  • Microscopic polyangitis (MPA)
    • Necrotising vasculitis, with few or no immune deposits, predominantly affecting small vessels
    • Necrotising glomerulonephritis is very common
    • Granulomatous inflammation is absent
    • shares many features of GPA but lacks granulomatous features such as URT features characteristic of GPA
    • As GPA- note that MPA tends to be MPO-ANCA and GPA tends to be PR3-ANCA
  • Eosinophilic granulomatosis with polyangitis (EGPA) (or Churg-Strauss syndrome)
    • Eosinophil rich and necrotising granulomatous inflammation often involving the respiratory tract; and necrotising vasculitis mainly affecting small-medium vessels
    • Associated with late-onset asthma and eosinophilia
    • ANCA is more frequent when glomerulonephritis is present, although renal involvement, in general, is less common than in GPA and MPA

Clinical features

  • Prodromal ‘flu-like’ illness is common; lasting weeks-months
    • Fever, polymyalgia, polyarthralgia, headache, malaise, anorexia, weight loss
  • Upper-airways disease most common presenting feature
    • Nasal obstruction, nasal ulcers, septal perforation, sinusitis; serosanguinous discharge (crusting) or epistaxis
    • Destruction of the septum can result in ‘saddle-nose’ deformity
  • Pulmonary involvement
    • Cough, haemoptysis, pleuritis
  • Skin (50%)
    • ulcers, palpable purpura (commonly of the lower extremities), papules, nodules
  • Ocular disease (50%)
    • associated with keratitis, conjunctivitis, scleritis, episcleritis, uveitis, retinal vessel occlusion and optic neuritis
    • visual loss occurs in <8% of patients
  • Musculoskeletal
    • Arthralgia/myalgia are common, as is synovitis
  • Nervous
    • Mononeuritis multiplex
  • Renal
    • Although not a presentation- pauci-immune focal segmental necrotising glomerulonephritis

Investigations

  • FBC, U&Es (particularly renal function), LFTs
    • ANCA screen
    • CRP/ESR/PV
  • Urinalysis- haematuria, proteinuria
  • CXR- pulmonary infiltrates and lymphadenopathy
  • Tissue biopsy

Management

  • Cyclosporin or rituximab and high dose steroids initially
    • Can step down to azathioprine and steroids
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