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Henoch–Schönlein purpura

Specialties > Child health

Background knowledge 🧠

Definition

  • Henoch–Schönlein purpura (HSP), also known as IgA vasculitis, is an immune-mediated small vessel vasculitis.
  • Characterised by palpable purpura, arthritis/arthralgia, abdominal pain, and renal involvement.
  • Primarily affects children, but can occur in adults.

Epidemiology

  • Most common vasculitis in children.
  • Peak incidence between 3-15 years of age.
  • Slight male predominance (2:1).
  • Seasonal variation, more common in autumn and winter.
  • Incidence in the UK: approximately 20 per 100,000 children per year.

Aetiology and pathophysiology

  • Exact cause is unknown, but often follows an upper respiratory tract infection.
  • Immune complex deposition, particularly IgA, in small vessels leads to inflammation.
  • Leads to vascular damage and characteristic clinical features.
  • Genetic predisposition may play a role.

Types

  • Classic HSP: presents with skin, joint, gastrointestinal, and renal involvement.
  • Atypical HSP: may lack one of the hallmark features (e.g., no purpura).
  • Severe HSP: significant renal involvement, potentially leading to chronic kidney disease.

Clinical Features 🌡️

Symptoms

  • Purpura: palpable, non-blanching rash, typically on buttocks and lower limbs.
  • Abdominal pain: colicky, can be severe, often with nausea and vomiting.
  • Arthralgia/arthritis: commonly affects knees and ankles, usually self-limiting.
  • Renal involvement: haematuria, proteinuria, hypertension (usually mild).
  • Systemic symptoms: fever, malaise, anorexia.

Signs

  • Palpable purpura: key diagnostic sign, typically symmetrical and in gravity-dependent areas.
  • Swollen, tender joints: particularly in lower extremities.
  • Abdominal tenderness: especially in the right lower quadrant.
  • Haematuria or proteinuria: detected on urinalysis, indicating renal involvement.
  • Hypertension: may be present, especially in cases with renal involvement.

Investigations 🧪

Tests

  • Urinalysis: check for haematuria, proteinuria.
  • Blood tests: FBC, U&E, LFTs, CRP, ESR, clotting screen.
  • Renal function tests: creatinine, eGFR to assess renal involvement.
  • Skin biopsy: rarely needed, shows leukocytoclastic vasculitis with IgA deposition.
  • Imaging: abdominal ultrasound if severe abdominal pain or suspected intussusception.

Management 🥼

Management

  • Supportive care: rest, hydration, and pain management (e.g., paracetamol, NSAIDs).
  • Corticosteroids: considered in severe cases, particularly with significant renal or gastrointestinal involvement.
  • Monitor renal function: regular urinalysis and blood pressure checks.
  • Hospital admission: required if there is severe abdominal pain, renal impairment, or other complications.
  • Referral to specialist: nephrology for renal involvement, paediatricians in children.

Complications

  • Renal involvement: can progress to nephrotic syndrome, chronic kidney disease in severe cases.
  • Gastrointestinal complications: intussusception, bowel ischaemia (rare).
  • Hypertension: secondary to renal involvement.
  • Recurrence: can recur in up to one-third of cases, usually within the first few months.
  • Chronic kidney disease: long-term complication in severe renal involvement.

Prognosis

  • Generally good, with most children recovering fully within weeks to months.
  • Prognosis worse in adults and those with significant renal involvement.
  • Long-term follow-up required in cases with renal involvement.
  • Monitoring for recurrence is important, particularly in the first year.
  • Chronic kidney disease can develop in a minority of cases.

Key Points

  • HSP is the most common small vessel vasculitis in children, often following a respiratory infection.
  • Clinical diagnosis is typically based on the presence of palpable purpura, arthralgia, abdominal pain, and renal involvement.
  • Management is largely supportive, with corticosteroids reserved for severe cases.
  • Long-term outcomes are generally good, but renal monitoring is crucial.
  • Complications can include chronic kidney disease and recurrence.

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