Henoch-Schönlein Purpura (IgA Vasculitis)
Summary
Henoch-Schönlein Purpura (HSP), now formally known as IgA Vasculitis (IgAV), is the most common vasculitis in children. It is a small vessel vasculitis characterised by IgA-dominant immune complex deposition. The classic presentation is a tetrad of features: Purpura (palpable, non-thrombocytopenic), Arthritis/Arthralgia, Abdominal Pain, and Renal Involvement. It typically occurs in children aged 3-10 years, often following an upper respiratory tract infection. The condition is usually self-limiting within 4-6 weeks, but renal involvement (HSP Nephritis = IgA Nephropathy) can lead to long-term morbidity and requires monitoring. Supportive care is the mainstay; steroids may be used for severe abdominal or joint symptoms. Long-term urinalysis and BP monitoring for at least 6-12 months is essential. [1,2]
Clinical Pearls
Palpable Purpura = Vasculitis: The rash is palpable (raised) because it is due to vessel inflammation, not just bleeding. Non-blanching.
"Buttocks and Legs": Rash is characteristically on lower limbs and buttocks (gravity-dependent areas). This distribution is classic.
Renal Surveillance is Key: Most children recover fully, but ~1-2% develop significant renal disease. Monitor urinalysis and BP for 6-12 months.
Watch for Intussusception: Severe abdominal pain in HSP may indicate intussusception (ileocolic involvement). Requires USS/Surgery.
Demographics
- Age: Peak 4-7 years. 90% of cases in children less than 10 years.
- Sex: Male > Female (2:1).
- Seasonality: More common in Winter/Spring (follows URTI season).
Incidence
- Most common childhood systemic vasculitis.
- Incidence: ~10-20 per 100,000 children per year.
Triggers
- Upper Respiratory Tract Infection (URTI): Most common trigger. Streptococcal, Viral (EBV, Varicella).
- Medications: Rare trigger.
- Vaccinations: Rarely associated.
Mechanism
- Trigger (Often URTI): Infection stimulates immune response.
- IgA Production: Excessive or abnormal IgA1 production.
- Immune Complex Formation: IgA-containing immune complexes form.
- Deposition in Small Vessels: Complexes deposit in walls of small vessels (Skin, Joints, GI tract, Kidneys).
- Inflammation (Small Vessel Vasculitis): Complement activation and neutrophil infiltration → Vessel wall damage → Leukocytoclasis.
- Clinical Manifestations: Purpura (skin vessels), Arthritis (joint vessels), Abdominal pain (GI vessels), Nephritis (Glomeruli – IgA Nephropathy pattern).
Histopathology
- Skin Biopsy: Leukocytoclastic vasculitis. IgA deposition on immunofluorescence.
- Renal Biopsy (If Done): Mesangial proliferative glomerulonephritis. Mesangial IgA deposits. (Identical to Primary IgA Nephropathy).
| Condition | Key Features |
|---|---|
| Henoch-Schönlein Purpura (IgA Vasculitis) | Child. Palpable purpura (buttocks/legs). Arthralgia. Abdominal pain. Haematuria. Normal platelets. |
| Meningococcal Septicaemia | Rapidly evolving non-blanching rash. Unwell child. Shock. Petechiae progressing to purpura fulminans. EMERGENCY. |
| ITP (Immune Thrombocytopenic Purpura) | Non-palpable petechiae/bruising. Low Platelets. No systemic symptoms. |
| Child Abuse (NAI) | Bruising in unusual locations. Pattern injuries. Safeguarding concern. |
| Hypersensitivity Vasculitis | Drug reaction. May have similar rash. History of drug exposure. |
| Acute Post-Streptococcal Glomerulonephritis | Gross haematuria, Oedema, Hypertension. Follows Strep infection. Low C3. No purpura. |
| Kawasaki Disease | Fever ≥5 days, Conjunctivitis, Rash (not typically purpuric), Mucosal changes, Extremity changes. CREAM criteria. |
1. Skin: Palpable Purpura (100%)
- Appearance: Non-blanching, palpable (raised) rash. Petechiae, Purpura, Ecchymoses.
- Distribution: Buttocks and Extensor surfaces of lower limbs (Gravity-dependent). May also involve upper limbs. Spares trunk usually.
- Evolution: May start as urticarial lesions before becoming purpuric.
- Key Feature: Palpable – distinguishes from ITP/other non-vasculitic purpura.
2. Joints: Arthritis/Arthralgia (~75%)
- Joints Affected: Large joints – Knees, Ankles. Sometimes Wrists, Elbows.
- Features: Pain, Swelling, Limitation of movement. Periarticular. Migratory.
- Transient: Resolves without permanent damage. Non-erosive.
3. Gastrointestinal (~50-70%)
- Abdominal Pain: Colicky. Central.
- Cause: Vasculitis of GI tract wall → Oedema, Haemorrhage, Ischaemia.
- Complications:
- GI Bleeding: Occult blood, Melaena, Haematemesis.
- Intussusception: Ileocolic most common. Bowel wall oedema acts as lead point. RED FLAG – Requires urgent USS, ± Surgical reduction.
- Bowel Infarction / Perforation: Rare but serious.
4. Renal (~30-50%)
- Spectrum: Microscopic haematuria → Proteinuria → Nephritic Syndrome → Nephrotic Syndrome → Rapidly Progressive GN (Rare).
- Timing: May occur at presentation or develop weeks to months later.
- Significance: Main determinant of long-term morbidity. ~1-2% develop chronic kidney disease.
- Histology (if Biopsy): IgA Nephropathy (Mesangial IgA deposition).
5. Other Systems
| System | Features |
|---|---|
| Scrotal / Testicular | Scrotal oedema, Orchitis. Can mimic Testicular Torsion. |
| CNS (Rare) | Headache, Seizures, Altered consciousness. |
| Pulmonary (Rare) | Pulmonary haemorrhage. |
Diagnosis is Clinical (No Specific Test)
- Platelet Count: NORMAL – Excludes ITP.
- FBC: Usually normal. May have mild leucocytosis, raised ESR.
- Renal Function: U&E, Creatinine – Usually normal unless significant nephritis.
- Urinalysis: Essential. Check for Haematuria, Proteinuria. Urine PCR if protein detected.
- Serum IgA: May be elevated (~50%), but not diagnostic.
- C3/C4 (Complement): Normal (Distinguishes from PSGN where C3 is low).
- ASOT / Anti-DNase B: May be elevated if recent Strep infection (trigger), but not specific.
- Stool: Occult blood if GI involvement suspected.
- Skin Biopsy: Rarely needed. Shows Leukocytoclastic Vasculitis + IgA on IF.
- USS Abdomen: If intussusception suspected (Target sign).
Management Algorithm
CHILD WITH PALPABLE PURPURA
+ Arthralgia / Abdominal Pain / Haematuria
↓
DIAGNOSIS: HENOCH-SCHÖNLEIN PURPURA (IgA Vasculitis)
(Clinical Diagnosis – No specific test)
┌──────────────────────────────────────────────┐
│ CHECK: │
│ - Platelet Count (NORMAL rules out ITP) │
│ - Urinalysis (Haematuria, Proteinuria) │
│ - BP │
│ - Renal Function (U&E) │
└──────────────────────────────────────────────┘
↓
ASSESS FOR SEVERE COMPLICATIONS
(Intussusception, Renal Insufficiency, GI Bleed)
┌────────────────┴────────────────┐
COMPLICATED UNCOMPLICATED
↓ ↓
ADMIT / INVESTIGATE SUPPORTIVE CARE
(See Below) (Outpatient)
↓
SUPPORTIVE MANAGEMENT (Majority)
┌──────────────────────────────────────────────┐
│ - Analgesia: Paracetamol. NSAIDs (if no │
│ renal/GI concerns) for joint pain. │
│ - Hydration │
│ - Rest │
│ - Most resolve in 4-6 weeks. │
└──────────────────────────────────────────────┘
↓
STEROIDS (Considered for)
┌──────────────────────────────────────────────┐
│ - Severe Abdominal Pain (May reduce duration│
│ and risk of intussusception - debated) │
│ - Severe Arthritis │
│ - Scrotal Oedema │
│ - Prednisolone 1-2mg/kg/day for 1-2 weeks, │
│ then taper. │
│ (Steroids do NOT prevent renal disease) │
└──────────────────────────────────────────────┘
↓
RENAL INVOLVEMENT?
┌────────────────┴────────────────┐
YES (Significant Proteinuria, NO
Nephritic/Nephrotic Syndrome,
Renal Impairment)
↓ ↓
REFER PAEDIATRIC MONITOR URINALYSIS
NEPHROLOGY + BP
- Consider Renal Biopsy Weekly initially,
- ACEi for Proteinuria then monthly for
- Steroids +/- Immuno- 6-12 months
suppression for
Severe Nephritis
Supportive Care
- Hydration, Rest, Analgesia.
- Paracetamol: First-line for pain.
- NSAIDs: For significant joint pain. Avoid if significant renal or GI involvement.
Corticosteroids
- Indication: Severe abdominal pain, Severe arthritis, Scrotal involvement.
- Dose: Prednisolone 1-2 mg/kg/day (Max 60mg) for 1-2 weeks, tapered.
- Note: Steroids may shorten duration of abdominal/joint symptoms but do NOT prevent or treat nephritis.
Renal Involvement
- Regular Urinalysis + BP Monitoring: Weekly initially, then monthly for 6-12 months.
- ACE Inhibitor: If persistent proteinuria.
- Nephrology Referral: If significant proteinuria (PCR >100), Nephritic/Nephrotic syndrome, Renal impairment.
- Renal Biopsy: If severe nephritis to guide immunosuppression.
- Immunosuppression (Severe Nephritis): Steroids, Cyclophosphamide, MMF (Specialist decision).
| Complication | Notes |
|---|---|
| HSP Nephritis | Most important long-term complication. ~30-50% have some renal involvement. ~1-2% develop CKD. |
| Intussusception | ~2-3%. Usually Ileocolic. Bowel wall oedema acts as lead point. USS + Reduction. |
| GI Haemorrhage | Usually mild. Severe haemorrhage is rare. |
| Bowel Infarction / Perforation | Rare. |
| Recurrence | ~30% relapse, usually milder. Often within first 3 months. |
- Most Children Recover Fully: 90-95% without long-term sequelae.
- Self-Limiting: Usually resolves in 4-6 weeks.
- Renal Long-Term: ~1-2% develop significant CKD. Risk factors: Severe initial nephritis, Older age, Nephrotic-range proteinuria.
- Recurrence: ~30%, usually within 3 months. Relapses are typically milder.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| IgA Vasculitis (HSP) Management | ACR/EULAR (SHARE Initiative) | Supportive care. Steroids for severe symptoms. Renal monitoring. |
| NICE CKS | NICE | Urinalysis monitoring for 6-12 months. |
What is Henoch-Schönlein Purpura?
HSP is a condition where the small blood vessels become inflamed. This causes a characteristic rash (purplish spots on the legs and bottom) and can also affect the joints (causing pain), the tummy (causing cramps), and the kidneys.
Why did my child get it?
We don't know exactly, but it often happens after a viral or bacterial infection (like a cold or sore throat). The immune system overreacts and attacks the blood vessel walls.
Is it serious?
Usually not. Most children recover completely within a few weeks. However, we need to monitor the urine and blood pressure for several months to check the kidneys are not affected.
What is the treatment?
Usually just rest and pain relief. Sometimes we use a short course of steroids if the tummy pain or joint pain is severe. The most important thing is to check the urine regularly to make sure the kidneys are OK.
Primary Sources
- Ozen S, et al. EULAR/PReS endorsed consensus criteria for the classification of childhood vasculitides. Ann Rheum Dis. 2006;65(7):936-41. PMID: 16322081.
- Trnka P. Henoch-Schönlein purpura in children. J Paediatr Child Health. 2013;49(12):995-1003. PMID: 24134426.
Common Exam Questions
- Classic Tetrad: "What are the four main features of HSP?"
- Answer: Palpable Purpura, Arthritis/Arthralgia, Abdominal Pain, Renal Involvement (Haematuria/Proteinuria).
- Rash Distribution: "Where is the rash typically located in HSP?"
- Answer: Buttocks and Extensor surfaces of Lower Limbs (Gravity-dependent).
- Key Investigation: "How do you distinguish HSP from ITP?"
- Answer: Platelet count. HSP = Normal Platelets. ITP = Low Platelets.
- Long-Term Complication: "What is the main determinant of long-term morbidity in HSP?"
- Answer: Renal Involvement (HSP Nephritis / IgA Nephropathy). Requires monitoring.
Viva Points
- Intussusception in HSP: Explain mechanism (Bowel wall oedema as lead point).
- Renal Monitoring Duration: Urinalysis and BP for 6-12 months.
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