Henoch-Schönlein Purpura (Immunoglobulin A Vasculitis)

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Henoch-Schönlein purpura (HSP) is now referred to as immunoglobulin A (IgA) vasculitis (IgAV).
  • A systemic immune-mediated vasculitis involving the small blood vessels of skin, gastrointestinal (GI) tract, joints, and kidneys characterized by nonthrombocytopenic purpura, abdominal pain, arthritis, and glomerulonephritis
  • The 2010 classification criteria for IgAV created by the European League Against Rheumatism/Pediatric Rheumatology International Trials Organization/Pediatric Rheumatology European Society (100% sensitivity, 87% specificity) include the presence of palpable purpura with lower limb predominance plus at least one of the following:
    • Diffuse abdominal pain
    • Arthritis or arthralgia
    • Renal involvement (any hematuria and/or proteinuria)
    • Biopsy showing typical leukocytoclastic vasculitis or proliferative glomerulonephritis with predominant IgA deposition
      • If atypical distribution of purpura, IgA deposition on biopsy is required

EPIDEMIOLOGY

  • Most common cause of systemic vasculitis in childhood
  • Most frequent in 3- to 12-year-olds
    • Rare in <2 years of age
    • Mean age is 6.5 years.
  • Incidence of 3 to 26.7 cases per 100,000 children per year
  • Male predominance
  • No known variation in risk based on geography, race, or ethnicity
  • Most cases occur in winter.

ETIOLOGY

  • Genetically predisposed hosts may be more susceptible to triggers.
  • Climate may play a role.
  • 30–65% of cases preceded by upper respiratory tract infection (URI), particularly β-hemolytic streptococci
  • Other infectious associations include viral infections (varicella and hepatitis A and B), Mycoplasma pneumoniae, Bartonella henselae, and Helicobacter pylori.

RISK FACTORS

Genetics

  • Most often occurs sporadically.
  • Certain human leukocyte antigen types may be associated with increased risk.
  • Patients with complement deficiencies and IgA-related disorders may be predisposed.

PATHOPHYSIOLOGY

  • An IgA-mediated, dysregulated immune response leads to deposition of IgA and C3 immune complexes into small vessels (capillaries, arterioles, and venules).
  • Infiltration of neutrophils into the walls of small vessels leads to necrosis and scattered nuclear debris (leukocytoclastic vasculitis).
  • Recognition of galactose-deficient IgA1 by antiglycan antibodies may cause renal injury via mesangial deposition of immune complexes.
  • Proliferative glomerulonephritis with increased endothelial and mesangial cells, ranges from focal and segmental lesions to severe crescentic disease

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