IgA Vasculitis (Henoch-Schönlein Purpura)
Summary
IgA Vasculitis (formerly Henoch-Schönlein Purpura or HSP) is the most common systemic vasculitis in childhood. It is an immune-complex mediated small vessel vasculitis characterized by the tetrad of palpable purpura, arthralgia, abdominal pain, and renal disease. It is usually self-limiting but requires rigorous monitoring to detect nephritis. [1,2]
The Classic Tetrad
- Rash (100%): Palpable Purpura (non-blanching spots that you can feel). Symmetrical distribution on legs and buttocks.
- Arthritis (82%): Transient, migratory oligoarthritis (knees/ankles). Painful but non-destructive.
- Abdominal Pain (63%): Colicky pain, vomiting, or GI bleeding (from submucosal petechiae).
- Renal Involvement (40%): Haematuria and/or Proteinuria.
Clinical Pearls
The "BAPN" Protocol: The most critical part of management is NOT the acute treatment (which is supportive), but the Follow-up. Renal involvement can be delayed. Almost all guidelines mandate urine dipstick and BP monitoring for 6 months to catch silent nephritis before CKD sets in.
Intussusception Risk: While classic intussusception is ileo-colic, IgA vasculitis causes Ileo-Ileal intussusception due to bowel wall oedema acting as a lead point. It can be harder to diagnose on ultrasound.
Steroids Myth: Steroids reduce abdominal and joint pain significantly, but high-quality meta-analyses show they DO NOT prevent renal disease. They are for symptom control, not disease modification.
Demographics
- Age: Peak 4-6 years. 90% cases under 10.
- Gender: Male > Female (1.5:1).
- Season: Peak in Winter/Spring (following URTIs).
Mechanism
- Trigger: Viral (Adenovirus, Enterovirus) or Bacterial (Group A Strep) infection acts as an antigen.
- Defect: Patients have abnormal IgA1 (galactose-deficient).
- Complex Formation: Antibodies form against this IgA1 -> IgA Immune Complexes.
- Deposition: Complexes deposit in small vessels (skin, glomeruli, gut).
- Inflammation: Type III Hypersensitivity reaction activates complement -> Leukocytoclastic Vasculitis (neutrophil destruction of vessel wall).
- Renal Link: The renal pathology is identical to IgA Nephropathy (Berger's Disease).
Symptoms
Signs
- Skin: Press with glass (non-blanching). Feeling it ("palpable") distinguishes it from thrombocytopenic pupura (flat).
- Abdomen: Diffuse tenderness. Palpable mass?
- Genitals: Testicular exam mandatory in boys.
- Dipstick: Blood +++. Protein ++.
Diagnosis
- Clinical diagnosis based on EULAR/PRINTO criteria: Purpura/Petechiae (Mandatory) + 1 of:
- Abdominal Pain.
- Arthritis/Arthralgia.
- Renal Involvement.
- Biopsy (IgA deposition).
Tests
- Urine: Dipstick + Protein:Creatinine Ratio (PCR).
- BP: Monitor for hypertension.
- Bloods:
- FBC: Platelets are NORMAL or High (Thrombocytosis of inflammation). This excludes ITP and Leukaemia.
- Coagulation: Normal (Excludes Meningococcal Sepsis/DIC).
- U&E: Creatinine (baseline).
- ASOT: Anti-Streptolysin O (often raised).
- Ultrasound: If severe abdo pain (rule out Intussusception).
Management Algorithm
CHILD WITH PALPABLE PURPURA
↓
EXCLUDE OTHER CAUSES
- Meningococcal (Ill? Fever? Low BP?)
- ITP (Low Platelets?)
- Leukemia (Blasts?)
↓
CONFIRM IgA VASCULITIS
↓
ASSESS SEVERITY & TRIAGE
┌───────────────┴───────────────┐
MILD SEVERE
(Rash + Mild pain) (Severe Gut/Renal)
↓ ↓
DISCHARGE HOME ADMIT
- Analgesia (NSAIDs ok) - IV Fluids
- Rest (Legs up) - Steroids (Prednisolone)
- Education - Surgical R/V (Gut?)
↓ ↓
FOLLOW UP PATHWAY (MANDATORY)
- Urine Dip + BP measurement
- Day 7, 14, 28
- Month 2, 3, 4, 6
1. Acute Management
- Supportive: Hydration, rest.
- Analgesia: Paracetamol + NSAIDs (Naproxen/Ibuprofen).
- Note on NSAIDs: Safe unless active GI bleeding or significant renal impairment.
- Corticosteroids: Oral Prednisolone (1-2mg/kg for 1-2 weeks) indicated for:
- Severe colicky abdominal pain.
- Orchitis.
- Severe arthritis causing immobility.
2. Renal Management
- Referral to Paediatric Nephrology if:
- Persistent Proteinuria (>3 months).
- Nephrotic Syndrome.
- Impaired GFR / Hypertension.
- May require Renal Biopsy + Immunosuppression (Azathioprine/Cyclophosphamide).
- Intussusception (3%): "Redcurrant Jelly" stool.
- Chronic Kidney Disease (1-2%): The only long-term morbidity.
- Recurrence (30%): Usually milder than primary episode, triggered by next URI.
- Excellent: Self-limiting in 94% of children.
- Adults: If adults get IgA Vasculitis, the prognosis is worse (higher risk of CKD).
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| IgAV Management | SHARE (European) | Use EULAR criteria. Steroids for pain only. |
| Renal Monitoring | BAPN (UK Nephro) | 6-month monitoring schedule is gold standard. |
Landmark Evidence
1. Steroids and Renal Protection
- The CHART trial (Arch Dis Child) and subsequent meta-analyses confirmed early steroid treatment does not reduce the incidence of proteinuria at 6 or 12 months.
Is it Meningitis?
No. The rash looks similar (it doesn't vanish under a glass), but children with meningitis are extremely sick. Children with HSP are usually well in themselves, just sore. The blood tests show normal clotting cells, which proves it isn't meningitis or leukemia.
What causes it?
It is an over-reaction of the immune system, usually after a cold or sore throat. The immune system makes "sticky" antibodies that clog up the tiny blood vessels in the skin, tummy, and kidneys.
Will it come back?
It might. About 1 in 3 children get a milder rash again next time they catch a cold. It usually stops happening as they get older.
Why do we need to check urine?
The kidneys can be silently inflamed even after the rash has gone. We need to check the urine for 6 months to make sure no damage is happening.
Primary Sources
- Ozen S, et al. EULAR/PRINTO/PRES criteria for Henoch-Schönlein purpura, childhood polyarteritis nodosa, childhood Wegener granulomatosis and childhood Takayasu arteritis. Ann Rheum Dis. 2010.
- Dudley J, et al. Randomised, double-blind, placebo-controlled trial to determine whether steroids reduce the incidence of nephropathy in Henoch-Schonlein Purpura (HSP). Arch Dis Child. 2013.
- BAPN. The medical management of Paediatric IgA Vasculitis. 2023.
Common Exam Questions
- Diagnosis: "Palpable purpura + Joint pain?"
- Answer: IgA Vasculitis.
- Investigation: "Blood result to exclude ITP?"
- Answer: Platelet count (Low in ITP, Normal in HSP).
- Complication: "Severe bloody diarrhoea?"
- Answer: Intussusception.
- Management: "Role of steroids?"
- Answer: Symptom relief for abdo/joint pain. Does NOT prevent renal disease.
Viva Points
- Palpable Purpura: Why is it palpable? Because there is actual inflammation (vasculitis) and cellular infiltration in the dermis, swelling the vessel. In ITP/Meningococcal, it is just a leak of blood (flat).
- Renal Biopsy: What are the findings? Mesangial proliferation with IgA deposition on Immunofluorescence.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.