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IgA Vasculitis (Henoch-Schönlein Purpura)

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Overview

Formerly known as Henoch-Schönlein Purpura (HSP), IgA vasculitis is an IgA-mediated autoimmune hypersensitivity vasculitis of childhood whose main features are skin purpura, arthritis, abdominal pain, and nephritis. Its aetiology is unknown.

IgA immune complexes are involved in IgA vasculitis, depositing in the small blood vessels of the skin, joints, kidneys, and gastrointestinal tract. IgA vasculitis has some overlap with IgA nephropathy.

IgA vasculitis is often seen in children following an infection.

Epidemiology

  • Rare condition but 90% of cases happen in children under 10 years
  • Peak age of onset is 4-6 years
  • In adolescents and adults, it tends to be more severe and can have long-term renal complications
  • Caucasian people are more often affected

Risk Factors & Associations

  • Prior infection (such as an upper respiratory tract infection or less commonly, a gastrointestinal infection)
  • Age 2-10 years
  • Male sex
  • History of allergy 

Presentation

  • Palpable non-blanching purpura over the back of the legs, buttocks, and extensor surfaces of the arms
  • Abdominal pain
  • Joint pain
  • Signs of renal disease and IgA nephropathy:

Differential Diagnoses

Idiopathic thrombocytopenic purpura (ITP)

  • No preceding infection
  • No arthralgia
  • No abdominal pain
  • Platelet levels are low in ITP but normal in IgA vasculitis

Meningococcal septicaemia

  • Child is very unwell
  • Neck stiffness or photophobia may be present
  • Petechiae may be present

Haemolytic uraemic syndrome (HUS)

  • Preceding E.coli or Shigella infection present
  • Reticulocytes increased
  • Haptoglobins increased
  • Platelets decreased

IgA nephropathy

  • Both have haematuria
  • Rash is not present
  • Abdominal pain is not present
  • Arthritis is usually not present

Investigations

  • Blood pressure:
    • Assesses for renal involvement – blood pressure is raised if this is true
    • Monitored for at least 6 months even if initial results are normal
  • Urinalysis:
    • Assesses for renal involvement
    • May show haematuria or proteinuria or casts
  • Urea and electrolytes (U&Es):
    • Assesses for renal involvement
  • Skin biopsy if atypical rash is present e.g. extensive or diffuse
    • Shows leukocytoclastic vasculitis with IgA deposition
  • Renal biopsy – required to diagnose IgA nephropathy:
    • Shows mesangial IgA deposition

Management

Most cases of IgA vasculitis are self-limiting. Patients with mild symptoms without renal involvement can have supportive treatment e.g. pain relief and rehydration

  • If there is renal involvement, corticosteroids with immunosuppressants such as azathioprine, and mycophenolate mofetil are used.
  • If there is severe nephritis, IV cyclophosphamide and oral or IV corticosteroids are used

Monitoring

  • All patients diagnosed with IgA vasculitis should be followed for at least 6 to 12 months with urinalysis and blood pressure monitoring

Patient Advice

  • Patients should seek medical help if there is recurring palpable purpura with the onset of joint or abdominal pain or haematuria

Complications

  • Renal involvement happens in around 55% of children but is usually not serious
  • Renal involvement is worse and more severe in older children and adults
  • Renal involvement can range from microscopic haematuria to nephrotic syndrome and renal failure
  • Rare complications include myocardial infarction, pulmonary haemorrhage, keratitis, uveitis, headaches and seizures, gastrointestinal haemorrhage, and intussusception

Prognosis

  • Majority of patients resolve fully within four weeks
  • Around 1/3 have a relapse within the first year of onset
  • The long-term prognosis of HSP depends on the severity of renal impairment

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