IgA-mediated generalised vasculitis involving small vessels of the skin, GI tract, kidneys, joints, rarely the lungs and CNS

Aetiology

• HSP is the most common vasculitis in children
  • 75% of cases occur in children age 2-11
  • Rare in infants
• While the exact aetiology of HSP is unknown, it is thought to be immune-mediated
  • 75% of patients have had a preceding infection (URTI, pharyngeal, GI), most commonly GAS, 1-3 weeks before HSP develops - suggests a potential infectious trigger
  • Other proposed triggers include medications, vaccinations, and insect bites

Clinical features

Symptoms

• Purpuric rash typically over buttocks and lower limbs

• Colicky abdominal pain

• Bloody diarrhoea

• Arthralgia or arthritis, predominantly in the knees and ankles

  

Signs

• Patients may present with a fever
• Renal involvement (50%) - nephritis (hematuria and/or proteinuria)
• Often, a history of a recent upper respiratory tract infection

Investigations

Clinical diagnosis but other tests may be useful if uncertainty:

• Bloods:
  • FBC, U+Es, LFTs, inflammatory markers, complement levels
  • ANCAs and specific antibodies
  • Connective tissue disease screen
• Imaging: CXR and/or CT scan
• Nerve conduction tests
• Tissue biopsy: for definitive diagnosis in uncertain cases