Henoch-Schönlein Purpura (IgA Vasculitis)

1. Clinical Overview

Summary

Henoch-Schönlein Purpura (HSP), now formally known as IgA Vasculitis (IgAV), is the most common systemic vasculitis in children, with an incidence of 10-20 per 100,000 children per year. [1,2] It is a small vessel vasculitis characterised by IgA-dominant immune complex deposition affecting the skin, joints, gastrointestinal tract, and kidneys. [3,4]

The classic presentation is a tetrad of features:

1. Palpable Purpura (non-thrombocytopenic, buttocks and lower limbs)
2. Arthritis/Arthralgia (large joints - knees, ankles)
3. Abdominal Pain (GI vasculitis with risk of intussusception)
4. Renal Involvement (spectrum from microscopic haematuria to RPGN)

HSP typically occurs in children aged 4-7 years (90% less than 10 years), with a male predominance (2:1). [5,6] It often follows an upper respiratory tract infection (particularly Group A Streptococcus or viral pathogens), with peak incidence in winter and spring. [7] The condition is usually self-limiting within 4-6 weeks, but renal involvement (HSP Nephritis = IgA Nephropathy pattern) can lead to long-term morbidity and requires monitoring. [8,9]

Management is primarily supportive care with analgesia and hydration. Corticosteroids may be used for severe abdominal pain, severe arthritis, or scrotal involvement, but do NOT prevent or treat nephritis. [10,11] Long-term urinalysis and BP monitoring for at least 6-12 months is essential to detect late-onset or progressive renal disease. [12,13]

Clinical Pearls

Palpable Purpura = Vasculitis: The rash is palpable (raised) because it is due to vessel wall inflammation, not just bleeding. It is non-blanching and progresses from urticarial lesions to purpura.

"Buttocks and Legs": Rash is characteristically on gravity-dependent areas - lower limbs and buttocks. This distribution is pathognomonic. Upper limbs and face are rarely affected initially.

Normal Platelets are Key: HSP has normal platelet count - this distinguishes it from ITP and is a critical diagnostic feature. [14]

Renal Surveillance is Mandatory: Most children recover fully, but ~1-2% develop significant chronic kidney disease. Risk factors include: older age at onset, persistent proteinuria, nephrotic-range proteinuria, and crescentic glomerulonephritis on biopsy. [15,16]

Watch for Intussusception: Severe abdominal pain in HSP may indicate intussusception (ileocolic involvement). Bowel wall oedema acts as a lead point. Requires urgent USS and possible surgical reduction. Occurs in 2-3% of cases. [17]

Recurrence is Common: ~30% of patients experience at least one relapse, usually within the first 3 months. Relapses are typically milder than the initial episode. [18]

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2. Epidemiology

Demographics

Incidence and Prevalence

• Most common childhood systemic vasculitis worldwide
• Incidence: 10-20 per 100,000 children per year [1,2]
• Geographic variation: Higher rates reported in Mediterranean and Asian populations
• Annual incidence in UK: ~13-18 per 100,000 children aged 0-17 years [19]

Triggers and Precipitants

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3. Aetiology and Pathophysiology

Molecular Pathogenesis

Exam Detail: IgA Vasculitis Pathophysiology - Detailed Mechanism [3,4,20]

1. Trigger Stimulus (Infection, Drug, Unknown Antigen)

   • Mucosal immune system activated
   • Bacterial/viral antigens present to immune cells
   • Polyclonal B-cell activation in mucosa-associated lymphoid tissue (MALT)

2. Aberrant IgA1 Production

   • Production of galactose-deficient IgA1 (Gd-IgA1)
   • Normal IgA1 has O-glycans in hinge region with terminal galactose
   • In HSP/IgAV: Under-galactosylation of IgA1 hinge region
   • Exposed N-acetylgalactosamine (GalNAc) residues become immunogenic

3. Anti-Glycan Antibody Formation

   • IgG or IgA antibodies produced against Gd-IgA1
   • These bind to exposed GalNAc residues
   • Form IgA-containing immune complexes

4. Immune Complex Formation

   • Circulating IgA-IgG or IgA-IgA immune complexes
   • Polymeric IgA1 predominates (high molecular weight)
   • Poor hepatic clearance due to size and composition

5. Vascular Deposition

   • Immune complexes deposit in small vessel walls:
     • Skin: Dermal venules and capillaries
     • Joints: Synovial vessels
     • GI tract: Mesenteric and bowel wall vessels
     • Kidneys: Glomerular mesangium
   • Preferential deposition in post-capillary venules

6. Complement Activation and Inflammation

   • Alternative pathway activation (not classical pathway - C3/C4 normal)
   • C3 deposition in vessel walls
   • Neutrophil recruitment and activation
   • Release of reactive oxygen species and proteases
   • Leukocytoclasis (nuclear fragmentation of neutrophils)
   • Vessel wall necrosis → haemorrhage and thrombosis

7. Clinical Manifestations

   • Skin: Palpable purpura (dermal venule inflammation and RBC extravasation)
   • Joints: Arthritis (periarticular vessel inflammation → synovial effusion)
   • GI tract: Vasculitis of bowel wall → oedema, haemorrhage, ischaemia
   • Kidneys: Mesangial IgA deposition → glomerulonephritis (identical to IgA nephropathy)

Histopathology

Skin Biopsy (rarely needed for diagnosis):

• Light Microscopy: Leukocytoclastic vasculitis of dermal venules
  • Neutrophilic infiltration of vessel walls
  • Nuclear debris (leukocytoclasis)
  • Fibrinoid necrosis
  • Extravasated red blood cells
• Direct Immunofluorescence: Granular IgA deposition in vessel walls (diagnostic)
  • Also C3, sometimes IgM
  • IgA predominates (distinguishes from other small vessel vasculitides)

Renal Biopsy (indicated for significant nephritis):

• Light Microscopy:
  • Mesangial proliferative glomerulonephritis
  • Crescents (in severe cases - poor prognostic sign)
  • Endocapillary proliferation
  • Interstitial inflammation (if severe)
• Immunofluorescence: Mesangial IgA deposits (identical to primary IgA nephropathy)
  • Granular pattern
  • Also C3, IgG, IgM in varying amounts
• Electron Microscopy: Mesangial electron-dense deposits

GI Tract (if endoscopy performed):

• Submucosal oedema, haemorrhage, ulceration
• Vasculitis of submucosal vessels

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4. Classification and Diagnostic Criteria

EULAR/PRINTO/PRES Criteria (2010) [14]

Definition: Vasculitis with IgA-dominant immune deposits affecting small vessels (capillaries, venules, arterioles) with one or more of: skin, GI tract, kidney involvement.

Classification Criteria (Sensitivity 100%, Specificity 87%):

Mandatory Criterion:

• Palpable purpura (non-thrombocytopenic, non-blanching)

Plus at least ONE of:

1. Diffuse abdominal pain
2. Histopathology showing IgA deposition (skin or kidney)
3. Arthritis or arthralgia (acute)
4. Renal involvement (haematuria and/or proteinuria)

Note: These are classification criteria for research, not diagnostic criteria. Clinical diagnosis can be made on classic presentation alone.

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5. Clinical Presentation - The Classic Tetrad

1. Skin: Palpable Purpura (100%)

Appearance:

• Non-blanching, palpable (raised) rash
• Evolution: Urticarial lesions → petechiae → purpura → ecchymoses
• May coalesce to form larger purpuric patches
• Crops of lesions over days to weeks

Distribution:

• Buttocks and extensor surfaces of lower limbs (gravity-dependent) - PATHOGNOMONIC
• May extend to upper limbs in severe cases
• Usually spares trunk, face, palms, soles initially
• In non-ambulatory children (e.g., infants): can affect upper body

Key Diagnostic Feature:

• Palpable - distinguishes from non-vasculitic purpura (ITP, thrombocytopenia)
• Lesions may be tender
• No systemic features of infection (distinguishes from meningococcaemia)

Timeline:

• Rash may be the first manifestation (40-50%) OR
• May follow arthralgia/abdominal pain (50-60%)
• New crops can appear during disease course

2. Joints: Arthritis/Arthralgia (75%)

Joints Affected:

• Large joints predominantly: Knees, Ankles (most common)
• Also: Wrists, Elbows, fingers
• Usually polyarticular but can be monoarticular initially

Features:

• Periarticular oedema and tenderness
• Pain and limitation of movement
• Migratory pattern (moving from joint to joint)
• May cause refusal to weight-bear or walk

Nature:

• Non-erosive - no permanent joint damage
• Transient - resolves within days to weeks without sequelae
• Often the presenting feature (especially in younger children)
• May precede rash by days

Differential:

• Can mimic septic arthritis, reactive arthritis, juvenile idiopathic arthritis
• Normal platelet count and eventual rash appearance clinch diagnosis

3. Gastrointestinal (50-70%)

Symptoms:

• Colicky abdominal pain (most common) - central/periumbilical
• Vomiting
• Gastrointestinal bleeding:
  • Occult blood (common)
  • Melaena (20-30%)
  • Haematemesis (less common)
  • Haematochezia (fresh blood PR)

Mechanism:

• Vasculitis of submucosal vessels → oedema, haemorrhage, ischaemia
• Bowel wall inflammation and oedema

Severity Spectrum:

• Mild: Colicky pain, resolves spontaneously
• Moderate: Pain with bleeding, requires monitoring
• Severe: Complications (see below)

Complications (occur in 2-5%): [17]

Red Flags - Indications for Imaging/Surgical Review:

• Severe, persistent, or worsening abdominal pain
• Signs of peritonism
• Palpable abdominal mass
• Significant GI bleeding
• Vomiting with bile or blood

4. Renal (30-50%)

Spectrum of Renal Involvement: [8,9,15,16]

Timing:

• Can occur at presentation (30%) OR
• Develop weeks to months later (70%) - hence need for prolonged monitoring
• Median onset: 4 weeks after rash onset
• Late-onset nephritis (> 6 months) can occur in 5-10%

Investigations:

• Urinalysis: Essential at every visit. Detects haematuria (microscopic or macroscopic) and proteinuria.
• Urine PCR: Quantify proteinuria if dipstick positive. Nephrotic range = PCR > 250 mg/mmol or > 200 mg/mmol depending on local reference.
• U&E, Creatinine: Assess renal function. May be normal even with significant GN.
• BP: Hypertension suggests significant renal involvement.

Histology (if renal biopsy performed):

• Mesangial proliferative GN with IgA deposition (identical to primary IgA nephropathy)
• Crescentic GN in severe cases (poor prognosis)
• ISKDC Classification (International Study of Kidney Disease in Children):
  • "Grade I: Minimal change"
  • "Grade II: Mesangial proliferation"
  • "Grade III: less than 50% crescents"
  • "Grade IV: 50-75% crescents"
  • "Grade V: > 75% crescents"
  • "Grade VI: Membranoproliferative pattern"

Long-Term Renal Prognosis: [15,16]

• Majority (> 90%) have excellent renal outcome with no CKD
• 1-2% develop ESKD requiring dialysis/transplant
• Risk factors for poor renal outcome:
  • Persistent proteinuria > 6 months
  • Nephrotic-range proteinuria at onset
  • Crescentic GN on biopsy (> 50% crescents)
  • Older age at onset (> 10 years)
  • Recurrent episodes of HSP
  • Initial renal impairment

5. Other Systems

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6. Differential Diagnosis

Key Differentials with Comparison

Stepwise Diagnostic Approach

CHILD WITH NON-BLANCHING RASH
           ↓
    ASSESS WELLNESS
    ┌────────┴────────┐
UNWELL/SHOCKED      WELL
    ↓                 ↓
SEPSIS PROTOCOL   CHECK PLATELETS
(Meningococcal)    ┌────┴─────┐
Blood cultures   LOW      NORMAL
Antibiotics        ↓          ↓
               ITP/DIC    ASSESS RASH
               Coagulopathy  ┌────┴────┐
                          PALPABLE  NON-PALPABLE
                             ↓          ↓
                       VASCULITIS    Trauma/NAI
                       (HSP likely)   Consider other
                             ↓
                    ASSESS FOR HSP TETRAD
                    - Palpable purpura (buttocks/legs)
                    - Arthralgia
                    - Abdominal pain
                    - Urinalysis (haematuria/proteinuria)
                             ↓
                    DIAGNOSIS: HSP/IgAV

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7. Investigations

Diagnosis is Clinical (No Specific Diagnostic Test)

The diagnosis of HSP is primarily clinical, based on the characteristic tetrad of features. Investigations are performed to:

1. Exclude differentials (especially ITP, meningococcaemia)
2. Assess extent of organ involvement (especially renal)
3. Monitor disease progression

Initial Investigations

Specialist Investigations (if indicated)

Monitoring Investigations (During Follow-Up)

• Urinalysis: Weekly for first month, then monthly for 6-12 months minimum [12,13]
• Urine PCR: If proteinuria detected
• BP: At every visit
• U&E, Creatinine: If renal involvement present

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8. Management

Management Principles

1. Supportive care is the mainstay for most patients
2. Early recognition and management of complications (intussusception, severe nephritis)
3. Long-term renal surveillance (mandatory for all patients)
4. Corticosteroids for severe symptoms (NOT to prevent nephritis)

Management Algorithm

        CHILD WITH SUSPECTED HSP
        (Palpable purpura + arthralgia/abdominal pain/haematuria)
                     ↓
        CONFIRM DIAGNOSIS (Clinical)
        ┌─────────────────────────────────────┐
        │ Check:                              │
        │ - FBC (Normal Platelets)            │
        │ - Urinalysis (Haematuria/Proteinuria) │
        │ - BP                                │
        │ - U&E, Creatinine                   │
        │ - Stool (occult blood if GI symptoms) │
        └─────────────────────────────────────┘
                     ↓
        ASSESS SEVERITY AND COMPLICATIONS
        ┌──────────────┴──────────────┐
   UNCOMPLICATED              COMPLICATED
   (Majority)                 (10-20%)
        ↓                           ↓
  OUTPATIENT                  CONSIDER ADMISSION
  SUPPORTIVE CARE             ┌───────────────────────┐
        ↓                     │ Indications:          │
  ┌─────────────────┐         │ - Severe abdominal    │
  │ - Rest          │         │   pain/GI bleeding    │
  │ - Hydration     │         │ - Concern for         │
  │ - Analgesia:    │         │   intussusception     │
  │   Paracetamol   │         │ - Significant renal   │
  │   NSAIDs* (for  │         │   involvement (AKI,   │
  │   joint pain if │         │   nephritic syndrome) │
  │   no renal/GI   │         │ - Scrotal swelling    │
  │   concerns)     │         │ - Unable to tolerate  │
  │ - Safety-net    │         │   oral fluids         │
  │   advice        │         │ - Social concerns     │
  └─────────────────┘         └───────────────────────┘
        ↓                           ↓
  MONITOR                     INVESTIGATE + TREAT
  Rash, joints, GI, urine     Complications
        ↓                           ↓
  ┌──────────────────────────────────────┐
  │ CONSIDER CORTICOSTEROIDS IF:         │
  │ - Severe abdominal pain              │
  │ - Severe arthritis limiting mobility │
  │ - Scrotal involvement                │
  │                                      │
  │ Prednisolone: 1-2 mg/kg/day (max 60mg) │
  │ for 1-2 weeks, then taper            │
  │                                      │
  │ NOTE: Steroids do NOT prevent or     │
  │ treat nephritis                      │
  └──────────────────────────────────────┘
                     ↓
        ASSESS RENAL INVOLVEMENT
        ┌───────────┴───────────┐
   NONE/MINIMAL          SIGNIFICANT
   (Isolated microscopic (Nephrotic proteinuria,
   haematuria, mild      nephritic syndrome,
   proteinuria)          AKI, HTN)
        ↓                      ↓
   ROUTINE F/U          REFER PAEDIATRIC NEPHROLOGY
   Urinalysis + BP      ┌────────────────────────┐
   Weekly × 4 weeks     │ - Consider renal biopsy│
   Then monthly ×       │ - ACEi/ARB for         │
   6-12 months         │   proteinuria          │
                       │ - Steroids ± immuno-   │
                       │   suppression for      │
                       │   severe nephritis:    │
                       │   * Methylprednisolone │
                       │     pulses             │
                       │   * Cyclophosphamide   │
                       │   * MMF/Azathioprine   │
                       │ - Plasmapheresis for   │
                       │   RPGN (rare)          │
                       └────────────────────────┘
                              ↓
                    LONG-TERM MONITORING
                    Urinalysis, BP, renal function
                    Duration: ≥6-12 months
                    (Longer if persistent abnormalities)

Supportive Care (Mainstay for Majority)

General Measures:

• Rest during acute phase (especially if significant joint involvement)
• Hydration: Maintain adequate fluid intake
• Reassurance: Explain self-limiting nature to family

Analgesia:

• Paracetamol: First-line for pain (rash, joints, abdomen)
• NSAIDs: For significant arthralgia/arthritis
  • "Caution: Avoid if significant renal involvement (proteinuria, AKI) or active GI bleeding"
  • "Options: Ibuprofen 5-10 mg/kg TDS"

Dietary:

• No specific dietary restrictions
• May require temporary bowel rest if severe GI involvement

Corticosteroids [10,11]

Indications:

1. Severe abdominal pain (may reduce duration and possibly reduce intussusception risk - evidence debated)
2. Severe arthritis limiting mobility
3. Scrotal involvement (pain/swelling)
4. Severe extrarenal organ involvement

NOT indicated for:

• Mild symptoms manageable with supportive care
• Prevention of nephritis (multiple RCTs show no benefit) [11]
• Mild to moderate nephritis (ineffective)

Regimen:

• Prednisolone: 1-2 mg/kg/day (maximum 60 mg) orally
• Duration: 1-2 weeks, then taper over 1-2 weeks
• Total course: Usually 2-4 weeks

Evidence:

• Reduces duration of abdominal pain and joint symptoms [10]
• Does NOT prevent nephritis or improve renal outcomes [11]
• Possible reduction in intussusception risk (some studies suggest, others do not) [17]

Management of Renal Involvement [8,9,15]

Mild Renal Involvement (Isolated haematuria, mild proteinuria):

• Observation and monitoring
• Urinalysis and BP weekly initially, then monthly
• No specific treatment required

Moderate Proteinuria (Non-nephrotic):

• ACE inhibitor or ARB to reduce proteinuria
  • e.g., Enalapril 0.1 mg/kg/day, titrate up
  • Monitor BP, U&E, creatinine

Severe Nephritis (Nephrotic-range proteinuria, nephritic syndrome, AKI, crescentic GN on biopsy):

• Refer to Paediatric Nephrology
• Renal biopsy to assess severity and guide treatment
• Immunosuppression (evidence limited, based on case series and IgA nephropathy data):
  • "High-dose corticosteroids:"
    • Methylprednisolone IV pulses: 10-30 mg/kg (max 1g) daily × 3 days
    • Followed by oral prednisolone 1-2 mg/kg/day, taper over weeks
  • "Cyclophosphamide: For severe/crescentic GN"
    • IV: 500-750 mg/m² monthly × 6 months OR
    • Oral: 2 mg/kg/day × 8-12 weeks
  • "Mycophenolate Mofetil (MMF): Alternative to cyclophosphamide"
    • 1200 mg/m²/day divided BD
  • "Azathioprine: For maintenance after induction"
  • "Plasmapheresis: Anecdotal use in RPGN"

Evidence Base:

• No high-quality RCTs for treatment of HSP nephritis
• Extrapolation from IgA nephropathy and ANCA vasculitis treatment
• KDIGO guidelines suggest steroids ± cyclophosphamide for crescentic GN

Management of Complications

Intussusception: [17]

• Urgent USS abdomen (target sign diagnostic)
• Air or hydrostatic enema reduction (first-line if no perforation)
• Surgical reduction if enema fails or signs of perforation/ischaemia
• Post-reduction: Steroids may reduce recurrence risk

GI Bleeding:

• Resuscitation if significant bleeding
• Transfusion if severe anaemia/ongoing haemorrhage
• Endoscopy if massive or persistent bleeding (rarely needed)
• Surgery for perforation/infarction

Testicular Involvement:

• Urgent USS Doppler to exclude torsion
• If torsion excluded: Supportive care, analgesia, scrotal support
• Steroids if severe pain/swelling

CNS Involvement (rare):

• CT/MRI brain
• Neurology input
• High-dose steroids ± immunosuppression for severe features

Follow-Up and Monitoring [12,13]

All Patients (regardless of initial severity):

• Urinalysis and BP:
  • Weekly for first 4 weeks
  • Monthly for 6 months minimum (12 months preferred)
  • Longer if any persistent abnormalities
• Reason: Renal involvement can develop late (up to 6 months post-onset) in 5-10%

Patients with Renal Involvement:

• Prolonged monitoring: 12 months to lifelong (depending on severity)
• Regular U&E, creatinine, urine PCR
• Annual review if persistent proteinuria or reduced eGFR

Discharge Criteria from Follow-Up:

• No renal involvement for 6-12 months
• Normal urinalysis and BP throughout monitoring period

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9. Complications

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10. Prognosis and Outcomes

Short-Term Prognosis

• Self-limiting in majority: Resolution within 4-6 weeks [1,2]
• Rash: Resolves over 2-4 weeks (may have crops/relapses)
• Joints: Resolves within days to weeks. No permanent damage.
• GI symptoms: Usually resolve within 1-2 weeks. Complications rare (less than 5%).
• Hospital admission: Required in 10-20% (severe pain, complications)

Long-Term Prognosis

Overall:

• 90-95% of children recover fully without long-term sequelae [1,2,18]
• Main determinant of long-term morbidity: Renal involvement

Renal Outcomes: [15,16]

Risk Factors for Poor Renal Outcome:

• Persistent proteinuria > 6 months
• Nephrotic-range proteinuria at onset
• Macroscopic haematuria at onset
• Crescentic GN on biopsy (> 50% crescents)
• Older age at onset (> 10 years, adults worse)
• Severe initial renal impairment
• Recurrent episodes of HSP with renal involvement

Adult Outcomes (follow-up studies to 20-40 years): [16]

• Ronkainen et al. (2002): 24-year follow-up showed:
  • 80% normal renal function
  • 20% had proteinuria or hypertension
  • 8% had ESKD or renal insufficiency
  • Initial nephritis severity predicted outcome

Recurrence [18]

• 30% of patients experience at least one relapse
• Timing: Usually within first 3 months (80% of relapses)
• Nature: Relapses typically milder than initial episode
• Features: Rash most common relapsing feature. GI and renal less common.
• Impact: Recurrence per se does not worsen long-term prognosis UNLESS involves recurrent nephritis
• Triggers for relapse: Intercurrent infections, allergen exposure

Pregnancy Considerations (for female survivors with nephritis)

• Women with history of HSP nephritis and persistent proteinuria/CKD at higher risk of:
  • Pregnancy-induced hypertension/pre-eclampsia
  • Worsening proteinuria
  • Fetal complications (IUGR, preterm delivery)
• Pre-conception counselling recommended for those with ongoing renal abnormalities

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11. Prevention and Public Health

Primary Prevention

• No specific prevention strategies (unknown aetiology in most cases)
• General measures:
  • Good hygiene to reduce URTI incidence
  • Prompt treatment of streptococcal pharyngitis (may reduce incidence, no strong evidence)

Secondary Prevention

• Avoiding triggers if identified (specific drugs, allergens)
• Early recognition and monitoring of renal involvement to prevent progression

Tertiary Prevention

• Long-term renal surveillance to detect and treat CKD early
• BP control and proteinuria reduction (ACEi/ARB) to slow CKD progression

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12. Evidence and Guidelines

Key Guidelines

Level of Evidence for Key Interventions

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13. Patient and Layperson Explanation

What is Henoch-Schönlein Purpura (HSP)?

Henoch-Schönlein Purpura, also called IgA Vasculitis, is a condition where the small blood vessels become inflamed. This inflammation causes blood to leak out of the vessels, leading to a characteristic purple rash (like bruises) on the skin, especially on the legs and bottom.

It also affects other parts of the body:

• Joints: Can cause pain and swelling, usually in the knees and ankles
• Tummy (Gut): Can cause crampy tummy pain and sometimes bleeding
• Kidneys: Can cause blood or protein in the urine

Why did my child get HSP?

We don't know exactly why some children get HSP. It often happens after a cold, sore throat, or other infection. The body's immune system (which fights germs) becomes overactive and starts attacking the blood vessels by mistake.

It is NOT contagious - your child cannot pass it to others, and it is not caused by anything you or your child did wrong.

Is HSP serious? What will happen?

For most children, HSP is not serious and gets better on its own within a few weeks. The rash, joint pain, and tummy pain usually go away without any problems.

However, we need to watch the kidneys carefully because:

• About 1 in 3 children with HSP will have some kidney involvement (usually mild)
• Most of these children's kidneys recover completely
• A small number (about 1-2 in 100) can develop long-term kidney problems

That's why we check your child's urine and blood pressure regularly for several months after the rash appears.

What is the treatment?

There is no specific cure for HSP, but we can help your child feel more comfortable:

• Rest when needed
• Pain relief: Paracetamol (Calpol) for pain from the rash or joints
• Drink plenty of fluids
• Sometimes steroid medicine (like prednisolone) if your child has severe tummy pain or joint pain

Antibiotics do NOT help because HSP is not caused by bacteria.

What should I watch out for at home?

Seek urgent medical advice if:

• Severe tummy pain that doesn't go away or gets worse
• Vomiting blood or blood in poo (black, tarry stools or fresh red blood)
• Your child becomes very unwell, lethargic, or drowsy
• Swelling in the scrotum (boys) with severe pain
• Headache with confusion, drowsiness, or fits

How long will we need to be monitored?

We will check your child's urine and blood pressure:

• Weekly for the first month
• Monthly for at least 6 months (sometimes 12 months)

This is to make sure the kidneys are not affected, even if your child seems completely well.

Can HSP come back?

Yes, about 1 in 3 children get HSP again, usually within a few months. If it comes back, it is usually milder than the first time. We will manage it the same way.

What is the long-term outlook?

Excellent for most children. More than 9 out of 10 children with HSP recover completely with no long-term problems.

If there are kidney problems, we will monitor your child closely and may refer to a kidney specialist (nephrologist) to help look after them.

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14. References

Primary Sources

1. Ozen S, Pistorio A, Iusan SM, et al. EULAR/PRINTO/PRES criteria for Henoch-Schönlein purpura, childhood polyarteritis nodosa, childhood Wegener granulomatosis and childhood Takayasu arteritis: Ankara 2008. Part II: Final classification criteria. Ann Rheum Dis. 2010;69(5):798-806. PMID: 20413568. DOI: 10.1136/ard.2009.116657

2. Trnka P. Henoch-Schönlein purpura in children. J Paediatr Child Health. 2013;49(12):995-1003. PMID: 24134426. DOI: 10.1111/jpc.12403

3. Heineke MH, Ballering AV, Jamin A, Ben Mkaddem S, Monteiro RC, Van Egmond M. New insights in the pathogenesis of immunoglobulin A vasculitis (Henoch-Schönlein purpura). Autoimmun Rev. 2017;16(12):1246-1253. PMID: 29037967. DOI: 10.1016/j.autrev.2017.10.009

4. Pillebout E, Sunderkötter C. IgA vasculitis. Semin Immunopathol. 2021;43(5):729-738. PMID: 34414494. DOI: 10.1007/s00281-021-00874-9

5. Gardner-Medwin JM, Dolezalova P, Cummins C, Southwood TR. Incidence of Henoch-Schönlein purpura, Kawasaki disease, and rare vasculitides in children of different ethnic origins. Lancet. 2002;360(9341):1197-1202. PMID: 12401245. DOI: 10.1016/S0140-6736(02)11279-7

6. Yang YH, Hung CF, Hsu CR, et al. A nationwide survey on epidemiological characteristics of childhood Henoch-Schönlein purpura in Taiwan. Rheumatology (Oxford). 2005;44(5):618-622. PMID: 15671050. DOI: 10.1093/rheumatology/keh544

7. Piram M, Mahr A. Epidemiology of immunoglobulin A vasculitis (Henoch-Schönlein): current state of knowledge. Curr Opin Rheumatol. 2013;25(2):171-178. PMID: 23318734. DOI: 10.1097/BOR.0b013e32835d8e2a

8. Davin JC, Coppo R. Henoch-Schönlein purpura nephritis in children. Nat Rev Nephrol. 2014;10(10):563-573. PMID: 25072122. DOI: 10.1038/nrneph.2014.126

9. Chen JY, Mao JH. Henoch-Schönlein purpura nephritis in children: incidence, pathogenesis and management. World J Pediatr. 2015;11(1):29-34. PMID: 25557596. DOI: 10.1007/s12519-014-0534-5

10. Weiss PF, Feinstein JA, Luan X, Burnham JM, Feudtner C. Effects of corticosteroid on Henoch-Schönlein purpura: a systematic review. Pediatrics. 2007;120(5):1079-1087. PMID: 17974746. DOI: 10.1542/peds.2007-0667

11. Dudley J, Smith G, Llewelyn-Edwards A, Bayliss K, Pike K, Tizard J. Randomised, double-blind, placebo-controlled trial to determine whether steroids reduce the incidence and severity of nephropathy in Henoch-Schonlein Purpura (HSP). Arch Dis Child. 2013;98(10):756-763. PMID: 23898159. DOI: 10.1136/archdischild-2013-303642

12. Narchi H. Risk of long term renal impairment and duration of follow up recommended for Henoch-Schönlein purpura with normal or minimal urinary findings: a systematic review. Arch Dis Child. 2005;90(9):916-920. PMID: 16113133. DOI: 10.1136/adc.2005.074641

13. Oni L, Sampath S. Childhood IgA vasculitis (Henoch Schonlein Purpura)-advances and knowledge gaps. Front Pediatr. 2019;7:257. PMID: 31275913. DOI: 10.3389/fped.2019.00257

14. Ozen S, Ruperto N, Dillon MJ, et al. EULAR/PReS endorsed consensus criteria for the classification of childhood vasculitides. Ann Rheum Dis. 2006;65(7):936-941. PMID: 16322081. DOI: 10.1136/ard.2005.046300

15. Coppo R, Andrulli S, Amore A, et al. Predictors of outcome in Henoch-Schönlein nephritis in children and adults. Am J Kidney Dis. 2006;47(6):993-1003. PMID: 16731294. DOI: 10.1053/j.ajkd.2006.02.178

16. Ronkainen J, Nuutinen M, Koskimies O. The adult kidney 24 years after childhood Henoch-Schönlein purpura: a retrospective cohort study. Lancet. 2002;360(9334):666-670. PMID: 12241872. DOI: 10.1016/S0140-6736(02)09835-5

17. Soyer T, Egritas O, Atmaca E, Akman H, Ozturk H. Intussusception in children with Henoch Schönlein purpura: assessment of clinical factors. Pediatr Surg Int. 2011;27(5):487-490. PMID: 21120489. DOI: 10.1007/s00383-010-2818-x

18. Calvo-Río V, Loricera J, Mata C, et al. Henoch-Schönlein purpura in northern Spain: clinical spectrum of the disease in 417 patients from a single center. Medicine (Baltimore). 2014;93(2):106-113. PMID: 24646467. DOI: 10.1097/MD.0000000000000019

19. Hetland LE, Susrud KS, Lindahl KH, Bygum A. Henoch-Schönlein purpura: a literature review. Acta Derm Venereol. 2017;97(10):1160-1166. PMID: 28573297. DOI: 10.2340/00015555-2733

20. Suzuki H, Kiryluk K, Novak J, et al. The pathophysiology of IgA nephropathy. J Am Soc Nephrol. 2011;22(10):1795-1803. PMID: 21949093. DOI: 10.1681/ASN.2011050464

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15. Examination Focus

Common Viva Questions and Model Answers

1. "A 5-year-old boy presents with palpable purpura on his legs and buttocks. What is your differential diagnosis and how would you narrow it down?"

Model Answer:

"The key feature here is palpable purpura, which indicates vasculitis - inflammation of blood vessel walls. My differential includes:

Most likely:

• Henoch-Schönlein Purpura (IgA Vasculitis) - most common vasculitis in children, classic age group and distribution

Important to exclude:

• Meningococcal septicaemia - non-blanching rash but child would be systemically unwell, febrile, shocked
• ITP - would have low platelets and rash would be non-palpable petechiae/bruising
• NAI (Non-accidental injury) - bruising pattern inconsistent with history, safeguarding concerns

To narrow it down, I would:

1. Assess wellness: Is the child well or unwell? Meningococcaemia would be unwell/shocked.

2. Check platelets: HSP has normal platelets, ITP has low platelets.

3. Examine rash: HSP rash is palpable (raised), gravity-dependent (buttocks, extensor surfaces of legs), non-blanching.

4. Look for the tetrad:

   • Purpura ✓
   • Arthralgia? (Ask about joint pain, examine joints)
   • Abdominal pain? (Ask about tummy pain, GI bleeding)
   • Renal involvement? (Check urinalysis for haematuria/proteinuria)

5. Initial investigations:

   • FBC - normal platelets in HSP
   • Urinalysis - essential to detect renal involvement
   • BP - check for hypertension (renal involvement)

If the child is well, with normal platelets, palpable purpura in gravity-dependent distribution, plus arthralgia and/or abdominal pain, the diagnosis is HSP."

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2. "What are the key features of HSP and what is the pathophysiology?"

Model Answer:

"HSP, now called IgA Vasculitis, is a small vessel vasculitis characterised by IgA-dominant immune complex deposition.

Classic Tetrad:

1. Palpable purpura - non-thrombocytopenic, buttocks and lower limbs
2. Arthritis/arthralgia - large joints (knees, ankles)
3. Abdominal pain - GI vasculitis
4. Renal involvement - haematuria and/or proteinuria

Pathophysiology:

The mechanism involves:

1. Trigger - usually an upper respiratory tract infection (Strep, viral)

2. Aberrant IgA1 production - production of galactose-deficient IgA1 (Gd-IgA1) with under-galactosylation of the hinge region

3. Immune complex formation - antibodies form against Gd-IgA1, creating IgA-containing immune complexes

4. Vascular deposition - complexes deposit in small vessel walls (skin, joints, GI tract, kidneys - particularly glomerular mesangium)

5. Complement activation - alternative pathway activated (C3/C4 remain normal)

6. Inflammation - neutrophil recruitment, leukocytoclastic vasculitis, vessel wall damage

7. Clinical features:

   • Skin: Dermal venule inflammation → purpura
   • GI: Bowel wall vasculitis → pain, bleeding, oedema (intussusception risk)
   • Kidneys: Mesangial IgA deposition → glomerulonephritis (identical to IgA nephropathy)

Histology:

• Skin: Leukocytoclastic vasculitis with IgA deposition on immunofluorescence
• Kidney: Mesangial proliferative GN with mesangial IgA deposits"

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3. "How would you distinguish HSP from ITP clinically?"

Model Answer:

"Both HSP and ITP can present with non-blanching skin lesions in children, but they are easily distinguished:

Key discriminator: Platelet count

• HSP = normal platelets
• ITP = low platelets

The palpability of the rash is also diagnostic:

• HSP rash is raised (palpable) because it's due to vessel wall inflammation
• ITP rash is flat because it's just bleeding under the skin

Examination tip: Always palpate the rash and check the FBC in any child with non-blanching lesions."

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4. "A child with HSP has severe abdominal pain. What are you worried about and how would you investigate?"

Model Answer:

"Severe abdominal pain in HSP is concerning because of the risk of GI complications, particularly:

Main concern: Intussusception (2-3% of HSP cases)

• Mechanism: Bowel wall oedema from vasculitis acts as a lead point
• Usually ileocolic intussusception
• Presentation: Severe colicky pain, vomiting, palpable mass, bloody stool ('redcurrant jelly')

Other concerns:

• GI bleeding - significant haemorrhage (melaena, haematemesis)
• Bowel perforation - peritonitis, acute abdomen
• Bowel infarction - ischaemia due to severe vasculitis

Clinical Assessment:

1. Severity of pain - is it getting worse? Constant vs colicky?
2. Vomiting - bile-stained suggests obstruction
3. GI bleeding - melaena, fresh blood PR, haematemesis?
4. Examination:
   • Abdominal distension, palpable mass?
   • Peritonism? (guarding, rigidity, rebound)
   • Shock? (tachycardia, hypotension)

Investigations:

• Urgent abdominal USS - first-line investigation
  • Target sign = diagnostic of intussusception
  • Bowel wall thickening/oedema
  • Free fluid
• Bloods:
  • FBC (anaemia from bleeding)
  • U&E (dehydration, AKI)
  • Coagulation (if bleeding)
  • Group & Save (if surgery likely)
• Stool - occult blood
• CT abdomen - if USS inconclusive or concern for perforation (look for free air, bowel ischaemia)

Management:

• Keep nil by mouth, IV fluids
• Analgesia
• If intussusception confirmed: Air or hydrostatic enema reduction (first-line), or surgery if failed/perforation
• If perforation/infarction: Surgical emergency - laparotomy
• Consider steroids - may reduce symptoms and possibly reduce intussusception risk (evidence debated)

Red flags for surgical review:

• Peritonism
• Palpable mass
• Severe persistent pain
• Haemodynamic instability"

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5. "What is the most important long-term complication of HSP and how do you monitor for it?"

Model Answer:

"The most important long-term complication is HSP Nephritis (renal involvement).

Why it matters:

• Occurs in 30-50% of children with HSP
• Determines long-term morbidity - most other features (rash, joints, GI) resolve completely
• 1-2% of children with HSP develop chronic kidney disease or end-stage kidney disease

Spectrum of renal involvement:

• Mild: Isolated microscopic haematuria
• Moderate: Haematuria + proteinuria
• Severe: Nephrotic syndrome, nephritic syndrome, AKI, RPGN

Key point: Renal involvement can develop late - up to 6 months after the rash appears (though usually within 4 weeks).

Monitoring Protocol:

All children with HSP (regardless of initial severity):

• Urinalysis + BP:
  • Weekly for 4 weeks
  • Monthly for 6-12 months minimum
• Longer monitoring if any renal abnormalities detected

Why this duration?

• 30% develop nephritis at presentation
• 70% develop it later (median 4 weeks, up to 6 months)
• Late-onset nephritis can occur in children who initially had no renal involvement

If proteinuria/haematuria detected:

• Urine PCR to quantify proteinuria
• U&E, creatinine to assess renal function
• More frequent monitoring

Refer to Paediatric Nephrology if:

• Nephrotic-range proteinuria (PCR > 250 mg/mmol)
• Nephritic syndrome (haematuria + proteinuria + HTN ± AKI)
• Declining renal function
• Persistent proteinuria > 6 months

Long-term prognosis:

• Most recover fully
• Risk factors for CKD:
  • Persistent proteinuria > 6 months
  • Nephrotic-range proteinuria
  • Crescentic GN on biopsy
  • Older age at onset

Examination pearl: Even children who seem completely well and have no initial urine abnormalities must be monitored for 6-12 months, because renal involvement can be delayed."

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6. "What is the role of steroids in HSP?"

Model Answer:

"Steroids have a limited but specific role in HSP. It's important to understand what they do and don't do.

Steroids are indicated for:

1. Severe abdominal pain - reduces duration and severity of pain
2. Severe arthritis - if limiting mobility
3. Scrotal involvement - painful scrotal oedema/orchitis

Regimen:

• Prednisolone 1-2 mg/kg/day (max 60 mg) orally
• Duration: 1-2 weeks, then taper over 1-2 weeks

What steroids DO:

• Reduce symptom duration - abdominal pain and joint pain resolve faster [Weiss et al. 2007 systematic review]
• Possibly reduce intussusception risk - some studies suggest benefit, others don't (evidence conflicting)

What steroids do NOT do:

• Do NOT prevent nephritis - multiple high-quality RCTs (Dudley 2013, Ronkainen 2006) show no benefit
• Do NOT treat nephritis - ineffective for mild to moderate nephritis
• Do NOT improve long-term renal outcomes

Evidence:

• Weiss et al. (2007): Systematic review - steroids reduce abdominal pain duration
• Dudley et al. (2013): RCT - steroids did NOT reduce nephritis incidence or severity
• Ronkainen et al. (2006): RCT - early steroids did NOT prevent nephritis

For severe nephritis (nephrotic-range proteinuria, crescentic GN, RPGN):

• High-dose IV steroids (methylprednisolone pulses) ± other immunosuppression (cyclophosphamide, MMF) may be used
• Based on extrapolation from IgA nephropathy treatment (limited evidence)
• Specialist nephrology decision

Key message:

• Steroids for symptom control (pain), NOT to prevent or treat nephritis
• Most children do NOT need steroids - supportive care is sufficient
• Do not give steroids routinely to try to prevent renal involvement - they don't work for this"

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7. "Describe the examination findings you would look for in a child with suspected HSP."

Model Answer:

General Inspection:

• Well vs unwell (exclude meningococcaemia)
• Mobility - able to walk? (arthritis may limit weight-bearing)

Skin:

• Rash:
  • Palpable purpura - raised, non-blanching lesions
  • "Distribution: Buttocks and extensor surfaces of lower limbs (pathognomonic)"
    • Check: Buttocks, backs of legs, shins, ankles
    • May extend to upper limbs, trunk (in severe cases)
  • "Morphology: Petechiae → purpura → ecchymoses"
  • May see urticarial lesions (early stage before becoming purpuric)
  • Crops of lesions at different stages
• Palpate the rash - confirm it is raised (distinguishes from ITP)

Joints:

• Large joints: Knees, ankles, wrists, elbows
• Look for:
  • Periarticular swelling and oedema
  • Tenderness on palpation
  • Limitation of movement (ask child to flex/extend)
  • May be warm
• Pattern: Polyarticular or migratory

Abdomen:

• Inspect: Distension?
• Palpate:
  • Tenderness (especially periumbilical)
  • Guarding, rigidity (peritonism - red flag)
  • Palpable mass (intussusception)
• Auscultate: Bowel sounds (absent if ileus/obstruction)

Genitalia (in boys):

• Scrotal examination (if appropriate):
  • Scrotal swelling, oedema
  • Tenderness (orchitis/epididymitis)
  • "Red flag: Exclude testicular torsion (requires urgent USS Doppler)"

Cardiovascular:

• Blood pressure - check for hypertension (renal involvement)
• Heart sounds - usually normal (pericarditis rare)

Respiratory:

• Chest auscultation - usually normal (pulmonary haemorrhage extremely rare)

Urine:

• Urinalysis - essential part of examination
  • Check for haematuria (microscopic or macroscopic)
  • Check for proteinuria

Other:

• Temperature (may be low-grade fever, but high fever suggests infection)
• Lymphadenopathy (usually absent)

Examination pearls:

• Palpate the rash - key to distinguishing vasculitis from thrombocytopenia
• Check urinalysis - essential to detect renal involvement (even if asymptomatic)
• Check BP - marker of renal involvement
• Palpate abdomen - assess for complications (intussusception)"

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8. "What are the poor prognostic factors for renal outcome in HSP?"

Model Answer:

"The renal outcome is the main determinant of long-term prognosis in HSP. While 90-95% of children recover fully, 1-2% develop CKD or ESKD.

Poor Prognostic Factors (for renal outcome):

Clinical:

1. Persistent proteinuria > 6 months - strongest predictor of long-term CKD
2. Nephrotic-range proteinuria at onset (PCR > 250 mg/mmol) - 20-30% develop persistent renal abnormalities
3. Macroscopic haematuria at onset
4. Older age at onset (> 10 years in children, adults have worse prognosis)
5. Severe initial renal impairment - AKI, nephritic syndrome
6. Recurrent episodes of HSP with renal involvement

Histological (if renal biopsy performed):

1. Crescentic glomerulonephritis - especially > 50% crescents (ISKDC Grade IV-V)
   • Grade IV (50-75% crescents): Very poor prognosis
   • Grade V (> 75% crescents): Extremely poor, high risk of ESKD
2. Tubulointerstitial fibrosis - indicates chronicity
3. Severe mesangial proliferation
4. Endocapillary proliferation

Laboratory:

1. Hypertension at presentation
2. Elevated serum creatinine at onset
3. Low eGFR

Long-term follow-up data [Ronkainen et al. 2002, Lancet]:

• 24-year follow-up of childhood HSP:
  • 80% normal renal function
  • 20% had proteinuria or hypertension
  • 8% had ESKD or renal insufficiency
• Initial nephritis severity was the strongest predictor of adult renal disease

Clinical Application:

Children with high-risk features need:

• Closer monitoring - monthly urinalysis, BP, renal function
• Earlier nephrology referral
• Consider renal biopsy - to assess severity and guide treatment
• Long-term follow-up - may need lifelong monitoring

Children with isolated microscopic haematuria or mild proteinuria that resolves within 6 months have excellent prognosis and can usually be discharged after 12 months of normal urinalysis.

Key point: The majority of children do well, but a small subset (those with persistent, severe nephritis) need aggressive treatment and long-term monitoring to prevent progression to ESKD."

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High-Yield Examination Topics

For MRCPCH Clinical Examination:

1. Rash recognition - identify palpable purpura, distinguish from ITP/meningococcaemia
2. Classic tetrad - purpura, arthritis, abdominal pain, renal involvement
3. Normal platelets - key differentiating feature
4. Distribution - buttocks and lower limbs (gravity-dependent)
5. Renal monitoring - urinalysis and BP for 6-12 months (mandatory)

For MRCPCH Written Examination:

1. Pathophysiology - IgA immune complex deposition, leukocytoclastic vasculitis
2. Complications - intussusception (lead point = bowel wall oedema), HSP nephritis
3. Steroid role - symptom control, NOT to prevent nephritis
4. Renal prognosis - 1-2% CKD, risk factors (persistent proteinuria, crescentic GN)
5. Differential diagnosis - ITP (low platelets), meningococcaemia (unwell), NAI

For MRCPCH OSCE:

• History taking: Explore tetrad, post-URTI, exclude red flags (severe pain, GI bleeding)
• Examination: Demonstrate rash palpation, joint examination, abdominal examination, urinalysis
• Explanation to parents: Self-limiting, supportive care, importance of urine monitoring

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists and follow local protocols. Evidence-based medicine requires critical appraisal of primary literature and integration with clinical expertise and patient values.