Vasculitis (Including ANCA-Associated Vasculitis, Polyarteritis Nodosa, Takayasu Arteritis)

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Vasculitis = inflammation in a blood vessel wall, characterized by vessel size and infiltrate
    • Small vessel: arterioles, capillaries, venules
      • Examples: antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV; including granulomatosis with polyangiitis, microscopic polyangiitis [MPA], eosinophilic granulomatosis with polyangiitis [EGPA]), immunoglobulin A vasculitis (IgA) or Henoch-Schönlein purpura—see separate chapter), antiglomerular membrane disease
    • Medium vessel: main visceral arteries and their branches
      • Examples: polyarteritis nodosa (PAN), Kawasaki disease (See separate chapter.)
    • Large vessel: aorta and its major branches
      • Example: Takayasu arteritis (TA)
    • Variable vessel: any size artery, vein, or capillary
      • Example: Behçet disease (Silk Road disease)
    • Single organ:
      • Example: primary central nervous system vasculitis
    • Secondary vasculitis:
      • Example: Hepatitis, drugs, malignancy
  • Often results in multisystem organ dysfunction

EPIDEMIOLOGY

  • AAV
    • Rare in childhood
    • More common in 2nd decade of life than 1st
    • Female predominance in childhood
  • PAN
    • Extremely rare in childhood
    • Majority present at 9 to 10 years old
    • Equal in males and females
  • TA
    • Extremely rare in childhood
    • More common in adolescent children
      • Mean age 10.4 years
    • Female predominance

ETIOLOGY

  • Idiopathic/inflammatory:
    • Genetic predisposition in combination with environmental trigger/s
  • Infections (e.g., tuberculosis, streptococcus, hepatitis B)
  • Medications (e.g., thyroid medications)
  • Environmental exposure (e.g., silica dust)

PATHOPHYSIOLOGY

  • AAV:
    • granulomatosis with polyangiitis (GPA): granulomatous inflammation of the upper and lower respiratory tracts; necrotizing, pauci-immune glomerulonephritis; necrotizing vasculitis affecting predominantly small to medium vessels of other organs—any tissue can be affected.
    • MPA: necrotizing vasculitis with few or no immune deposits, mainly affecting small vessels; primarily affects lungs and kidneys
    • EGPA: eosinophil-rich and necrotizing granulomatous extravascular inflammation (such as respiratory tract) and necrotizing vasculitis (small to medium vessels) with asthma and eosinophilia; neuropathies due to vasculitis of vasa nervorum
  • PAN: necrotizing arteritis of small- and medium-sized arteries resulting in segmental fibrinoid necrosis; involvement of skin, muscle, nerve, and renal tissue
  • TA: granulomatous vasculitis of aorta and/or its main branches

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