Overview
IgA Vasculitis (Henoch-Schönlein Purpura)
1. Clinical Overview
Summary
IgA Vasculitis (IgAV), formerly known as Henoch-Schönlein Purpura (HSP), is the Most Common Vasculitis of Childhood, characterised by IgA-Mediated Small Vessel Vasculitis affecting the skin, Joints, Gastrointestinal tract, And kidneys. The classic tetrad includes Palpable Purpura (Without thrombocytopaenia), Arthritis/Arthralgia, Abdominal Pain, And Renal Involvement (Haematuria/Proteinuria). IgAV predominantly affects Children Aged 2-11 Years (Peak 4-6 years) but can occur in adults, Where it tends to be more severe. The aetiology is unknown but often follows an Upper Respiratory Infection. The disease is usually Self-Limiting in children, Resolving within 4-6 weeks, With Renal Involvement Being the Main Determinant of Long-Term Prognosis. Treatment is largely Supportive (Analgesia, Hydration), With Corticosteroids used for severe GI or joint symptoms, And more aggressive Immunosuppression for significant nephritis. [1,2,3]
Clinical Pearls
"Palpable Purpura on Legs/Buttocks in a Child": Classic presentation. Dependent areas.
"Purpura + Arthritis + Abdominal Pain + Renal Involvement = HSP Tetrad": Remember the four systems.
"Check the Urine": Renal involvement determines long-term outcome. Monitor urinalysis for months.
"Self-Limiting in Most Children": But follow up for renal manifestations.
2. Epidemiology
Demographics
| Factor | Notes |
|---|---|
| Incidence | ~10-20 per 100,000 children per year. |
| Age | Peak 4-6 years (Range 2-11). ~90% less than 10 years. Can occur in adults. |
| Sex | Male > Female (1.5-2:1). |
| Seasonality | More common in Autumn/Winter (Post-URTI). |
Precipitating Factors
| Factor | Notes |
|---|---|
| Upper Respiratory Tract Infection | Most common trigger (~50%). Group A Streptococcus, Viruses. |
| Drugs | NSAIDs, Antibiotics (Rare). |
| Vaccinations | Rarely reported. |
| Other Infections | Mycoplasma, Varicella. |
3. Pathophysiology
Mechanism
- Trigger (Usually URTI): Antigen exposure.
- Aberrant IgA Response: Increased production of poorly galactosylated (Galactose-deficient) IgA1.
- Immune Complex Formation: IgA-containing immune complexes.
- Deposition in Small Vessels: Skin (Dermal capillaries), Gut (Submucosal vessels), Kidneys (Glomeruli – Mesangium), Joints (Synovium).
- Complement Activation (Alternative Pathway): Inflammation.
- Vasculitis: Leucocytoclastic vasculitis. Vessel wall necrosis.
- Clinical Manifestations: Purpura, GI bleeding, Nephritis, Arthritis.
Histology
| Site | Findings |
|---|---|
| Skin | Leucocytoclastic vasculitis. Direct Immunofluorescence: IgA deposition in vessel walls. |
| Kidney | Mesangial proliferative glomerulonephritis. IgA deposition in mesangium (Identical to IgA Nephropathy). |
4. Clinical Presentation
Classic Tetrad
| Manifestation | Description | Notes |
|---|---|---|
| Skin (~95-100%) | Palpable Purpura: Non-blanching, Raised. Symmetrical. Dependent areas: Legs, Buttocks. May have petechiae, Ecchymoses, Urticaria-like lesions. | Mandatory for diagnosis. |
| Joints (~75%) | Arthralgia / Arthritis: Oligoarticular. Large joints (Knees, Ankles). Painful, Swollen, May limit walking. Non-erosive. Transient. | Resolves without sequelae. |
| GI (~50-75%) | Abdominal Pain: Colicky. Often periumbilical. Nausea, Vomiting, GI bleeding (Haematemesis, Melaena). Intussusception risk (~1-5%). | Can precede rash (Diagnostic challenge). |
| Renal (~30-50%) | Nephritis: Microscopic haematuria (Most common). Proteinuria. Hypertension. Nephrotic syndrome (Rare). Rapidly progressive GN (Rare). | Determines long-term prognosis. |
Other Manifestations
| Manifestation | Notes |
|---|---|
| Orchitis | Testicular pain/Swelling (~2-35% of boys). Exclude torsion. |
| CNS (Rare) | Headache, Seizures, Altered consciousness. |
| Pulmonary (Rare) | Haemorrhage. |
Symptoms
| Symptom | Notes |
|---|---|
| Rash | Often first noticed. May be preceded by malaise, Fever. |
| Leg/Joint Pain | Difficulty walking. |
| Abdominal Pain | Colicky. Worse after meals. |
| Blood in Stool/Vomit | GI involvement. |
| Decreased Urine Output / Oedema | Severe nephritis. |
5. Investigations
Diagnosis is Clinical (No Single Diagnostic Test)
- EULAR/PRINTO/PRES Criteria: Palpable purpura (Mandatory) + ≥1 of: Abdominal pain, Arthritis/Arthralgia, Renal involvement (Haematuria/Proteinuria), IgA deposits on biopsy.
Laboratory
| Test | Findings |
|---|---|
| Platelet Count | Normal (Distinguishes from ITP). |
| Coagulation (PT, APTT) | Normal. |
| FBC | May have mild leucocytosis, Anaemia (If GI bleed). |
| ESR / CRP | May be mildly elevated. |
| Renal Function (U&Es, Creatinine) | Check for renal impairment. |
| Urinalysis | Essential. Haematuria (Microscopic), Proteinuria. |
| Urine Protein:Creatinine Ratio | Quantify proteinuria. |
| Serum IgA | Elevated in ~50%. Not diagnostic. |
| ASOT / Throat Swab | If preceding streptococcal infection suspected. |
| Complement (C3, C4) | Normal (Alternative pathway activation). Helps exclude SLE/PIGN. |
Imaging
| Modality | Notes |
|---|---|
| Abdominal Ultrasound | If severe abdominal pain. Assess for Intussusception (Ileocolic target sign). Bowel wall thickening. |
| Doppler Ultrasound (Scrotum) | If orchitis suspected. Exclude torsion. |
Biopsy
| Site | Notes |
|---|---|
| Skin Biopsy | Leucocytoclastic vasculitis. IgA deposits on Direct Immunofluorescence. Usually not needed if typical presentation. |
| Renal Biopsy | Indicated for: Severe nephritis (Nephrotic syndrome, Renal impairment, Nephritic syndrome). Mesangial IgA deposits. Helps prognosticate. |
6. Management
Management Algorithm
SUSPECTED IgA VASCULITIS (HSP)
(Palpable purpura + Arthralgia/Abdominal pain/Renal)
↓
CONFIRM DIAGNOSIS (Clinical Criteria)
EXCLUDE DIFFERENTIALS (ITP, Sepsis, Meningococcaemia)
- Check Platelet count (Normal in HSP)
- Check Coagulation (Normal)
- Urinalysis (Essential)
↓
ASSESS SEVERITY
- Mild (Rash ± Mild arthralgia)
- Moderate (Significant arthritis, GI pain)
- Severe (GI bleed, Intussusception, Significant nephritis)
↓
TREATMENT (Largely Supportive)
┌──────────────────────────────────────────────────────────┐
│ **MILD DISEASE (Most)** │
│ - **Supportive Care**: Rest, Oral hydration │
│ - **Analgesia**: Paracetamol. (Avoid NSAIDs if renal │
│ concerns or significant GI symptoms) │
│ - Leg elevation for oedema │
│ - Self-limiting. Resolves 4-6 weeks. │
│ │
│ **MODERATE-SEVERE JOINT SYMPTOMS** │
│ - **Short Course Oral Corticosteroids** (Prednisolone │
│ 1-2 mg/kg/day for 1-2 weeks with taper) – Speeds │
│ resolution of arthritis/Abdominal pain. │
│ - NOT shown to prevent nephritis. │
│ │
│ **SEVERE GI SYMPTOMS (Haemorrhage, Severe Pain)** │
│ - **IV Corticosteroids** (Methylprednisolone) │
│ - NPO, IV Fluids │
│ - Surgical consult if intussusception (May require air │
│ enema or surgery) │
│ │
│ **SIGNIFICANT RENAL INVOLVEMENT (Nephritis)** │
│ - Refer to Paediatric Nephrology / Rheumatology │
│ - Mild (Isolated haematuria/Mild proteinuria): Monitor. │
│ - Moderate-Severe (Nephrotic, Nephritic, Renal │
│ impairment): Renal biopsy. Consider: │
│ - High-dose Corticosteroids │
│ - Immunosuppressants (Azathioprine, MMF, │
│ Cyclophosphamide) │
│ - ACE Inhibitor/ARB (For proteinuria) │
└──────────────────────────────────────────────────────────┘
↓
MONITORING (CRUCIAL)
┌──────────────────────────────────────────────────────────┐
│ **URINALYSIS** – Monitor for renal involvement. │
│ - Weekly during acute phase. │
│ - Monthly for 3-6 months after resolution. │
│ - Some recommend up to 6-12 months. │
│ - Check Blood Pressure. │
│ - Nephritis can develop after initial illness resolves. │
│ │
│ **RECURRENCE** – ~30% can have recurrence (Usually │
│ milder). Manage as per initial episode. │
└──────────────────────────────────────────────────────────┘
7. Differential Diagnosis
| Condition | Key Features |
|---|---|
| Immune Thrombocytopaenia (ITP) | Petechiae/Purpura. Low Platelet count (HSP = Normal). |
| Meningococcaemia | Non-blanching rash. Systemically unwell (Meningism, Shock). |
| Acute Leukaemia | Bruising, Pallor, Lymphadenopathy, Hepatosplenomegaly. Abnormal FBC. |
| Trauma / Non-Accidental Injury | Consider distribution. |
| Other Vasculitis | SLE, Polyarteritis nodosa (Adults). |
| Post-Streptococcal GN | Nephritis. Low C3. |
8. Complications
| Complication | Notes |
|---|---|
| Intussusception | ~1-5%. Ileo-ileal common. Presents with severe colicky pain, "Redcurrant jelly" stool, Sausage-shaped mass. Ultrasound. Air/Barium enema reduction or surgery. |
| GI Haemorrhage | Haematemesis, Melaena. |
| Protein-Losing Enteropathy | Rare. |
| Bowel Ischaemia/Perforation | Rare. |
| Chronic Kidney Disease / End-Stage Renal Disease | In those with severe nephritis. ~1-2% of children overall. Higher in adults. |
| Recurrence | ~30%. |
9. Prognosis and Outcomes
| Factor | Notes |
|---|---|
| Children | Excellent prognosis overall. Most recover fully within 4-6 weeks. |
| Renal Long-Term | Majority with mild nephritis recover. ~1-2% progress to ESRD. Severe initial nephritis predicts worse outcome. Follow-up essential. |
| Adults | Tend to have more severe disease, Higher nephritis rates, Poorer renal outcomes. |
| Recurrence | ~30% (Usually milder, Within 4-6 months). |
| Pregnancy | Women with history of HSP nephritis have increased pregnancy complications. Monitor. |
10. Evidence and Guidelines
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| IgA Vasculitis | EULAR/PRINTO/PRES, SHARE | Clinical diagnosis. Supportive care. Steroids for severe GI/Joint. Monitor urine. Nephrology referral for significant nephritis. |
11. Patient and Layperson Explanation
What is IgA Vasculitis (Henoch-Schönlein Purpura)?
IgA Vasculitis is a condition where small blood vessels become inflamed (Vasculitis). It causes a characteristic rash and can affect the joints, Tummy, And kidneys. It is the most common vasculitis in children and usually follows a viral infection like a cold.
What are the symptoms?
- Rash: Purple-red spots that don't fade when pressed (Palpable purpura), Mainly on legs and bottom.
- Joint Pain: Especially knees and ankles. Swelling.
- Tummy Pain: Crampy pain. Sometimes bloody poo.
- Kidney Involvement: Blood or protein in the urine (Often no symptoms initially, Detected on testing).
How is it treated?
Most children get better on their own within a few weeks with rest and paracetamol. Steroids (Prednisolone) may be used for severe joint or tummy pain. If kidneys are significantly affected, Specialist treatment may be needed.
What is the outlook?
Most children make a full recovery. The most important thing is to check the urine regularly for months afterwards, As kidney problems can sometimes develop later and need treatment.
Can it come back?
Yes, About a third of children may have another episode, But it is usually milder than the first.
12. References
Primary Sources
- Ozen S, et al. EULAR/PRINTO/PRES criteria for Henoch-Schönlein purpura. Ann Rheum Dis. 2010;69(5):798-806. PMID: 20413568.
- Saulsbury FT. Henoch-Schönlein purpura. Curr Opin Rheumatol. 2010;22(5):598-602.
- Piram M, et al. Short versus long-term course of corticosteroids in HSP: A randomized trial (SHARE Initiative). J Am Soc Nephrol. 2022.
13. Examination Focus
Common Exam Questions
- Classic Tetrad: "What are the four main features of Henoch-Schönlein Purpura?"
- Answer: Palpable Purpura, Arthritis/Arthralgia, Abdominal Pain (GI Involvement), Renal Involvement (Haematuria/Proteinuria).
- Platelet Count: "What is the platelet count in HSP and why is this important?"
- Answer: Normal. Distinguishes from Immune Thrombocytopaenia (ITP) which also causes purpura but has LOW platelets.
- Main Long-Term Concern: "What determines the long-term prognosis in HSP?"
- Answer: Renal Involvement (Nephritis). Can lead to CKD/ESRD in a small proportion.
- Histology: "What would you expect to see on direct immunofluorescence of a skin biopsy in HSP?"
- Answer: IgA Deposition in Small Vessel Walls.
Viva Points
- Rash Distribution: Legs and Buttocks (Dependent areas).
- Intussusception: Ileo-ileal most common in HSP. Surgical emergency.
- Self-Limiting in Most Children: 4-6 weeks.
- Monitor Urinalysis for Months: Nephritis can develop weeks after rash resolves.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.