Henoch–Schönlein Purpura (HSP)

Definition

• Henoch–Schönlein purpura (HSP) is the most common vasculitis in children, predominantly affecting small vessels(capillaries, venules, arterioles).

• Approximately 90% of cases occur in paediatric populations aged 2–8 years.

• Usually self-limiting but can impact multiple organ systems: skin, joints, gastrointestinal tract, and kidneys.

Aetiology & Causes

• Frequently follows an upper respiratory tract infection (URTI), often group A streptococcus

• Involves IgA immune complex deposition in small vessels (Type III hypersensitivity), leading to inflammation in skin, joints, gut, and kidneys

Symptoms

1. Palpable Purpura

   • Typically on lower limbs and buttocks, though can also appear on arms or face

   • Non-thrombocytopenic (platelet count normal) but raised lesions due to vasculitis

2. Arthritis/Arthralgia

   • Commonly affects knees and ankles, often migratory and transient

   • Joint swelling and pain but usually no long-term damage

3. Abdominal Pain

   • Sudden onset, diffuse or colicky, possibly with vomiting or bloody diarrhoea

   • Intussusception can occur as a rare but significant complication

4. Renal Involvement

   • Haematuria and/or proteinuria

   • Ranges from mild (microscopic haematuria) to more severe nephritic or nephrotic syndromes

Differential Diagnosis

• Idiopathic Thrombocytopenic Purpura (ITP): Usually low platelets (thrombocytopenia)

• Systemic Lupus Erythematosus (SLE): Multi-system involvement but often with ANA and other serologic findings

• Meningococcal Sepsis: Usually more acute presentation with significant systemic symptoms (fever, shock), non-blanching rash

Diagnosis

• Clinical Diagnosis: Based on the classic tetrad of palpable purpura, arthralgia, abdominal pain, and renal involvement

• Urinalysis: Confirms kidney involvement (RBCs, RBC casts, proteinuria)

• Blood Tests: Normal platelet count differentiates from ITP, inflammatory markers (ESR, CRP) may be elevated

• Further Investigations only if complications or atypical features (e.g. severe abdominal pain, suspected intussusception, significant renal impairment)

Management

1. Supportive Care

   • Self-Limiting in most children, typically resolving in weeks to months

   • Pain Relief: Paracetamol or NSAIDs (e.g. ibuprofen) for joint/muscle aches

2. Renal Monitoring

   • Monitor urinalysis and BP if there is kidney involvement

   • Persistent or severe proteinuria may necessitate nephrology referral

3. Severe Cases

   • Rarely, short-course corticosteroids are considered if severe abdominal pain or significant nephritis

   • Intussusception requires urgent surgical evaluation

4. General Advice

   • Rest, hydration, reassurance to parents/caregivers

   • Educate on signs of renal involvement (dark urine, oedema, hypertension)

Prognosis

• Overall, good outcome: Most children recover spontaneously within 3–4 weeks, with <5% developing serious chronic renal complications

• Follow-up with urinalysis for a few months to detect delayed or persistent renal involvement