IgA Vasculitis (Henoch Schönlein Purpura)
UK Kidney Association IgA vasculitis Guideline (RCPCH endorsed). Jul 2023.
Definition
IgA vasculitis is a small-vessel vasculitis, that most commonly affect the skin, joints, GI tract and the kidneys.
IgA vasculitis ≠ IgA nephropathy
IgA vasculitis and IgA nephropathy are related but distinct conditions:
- IgA vasculitis is a systemic small-vessel vasculitis caused by IgA immune-complex deposition
- IgA nephropathy is a primary renal disease with IgA deposition confined to the glomeruli
Epidemiology
IgA vasculitis is the most common vasculitis in children
Median age at presentation: 6 y/o
Aetiology
The exact cause and pathogenesis is known and believed to be multifactorial.
IgA vasculitis most commonly develops after a normal childhood illness
- Most commonly after an URTI
- Less common triggers are GI infections
Clinical Features
IgA vasculitis typically manifests within days to up to 2 weeks after a preceding URTI
Clinical features by affected organ system:
| Affected organ system | Frequency (%) | Clinical features |
|---|---|---|
| Skin | Mandatory feature (all patients) |
|
| Musculoskeletal | ~90% | Most commonly affecting the lower limb
|
| Gastrointestinal | ~70% |
|
| Kidneys | 40-50% | IgA nephropathy
See the IgA nephropathy section in the Nephrotic and Nephritic Syndromes article for more information. |
| Urological | ~15% of males |
|
Unlike other types of vasculitis, lung involvement (→ pulmonary haemorrhage) and cerebral involvement (→ cerebral vasculitis) are very uncommon.
Investigation and Diagnosis
IgA vasculitis is primarily a clinical diagnosis based on:
- Purpura / petechiae, and
- At least one of the following
- Acute abdominal pain
- Arthritis / arthralgia
- Renal involvement (proteinuria / haematuria)
- Histopathology
The presence of non-thrombocytopenic purpura is a key diagnostic feature:
Laboratory evaluation in IgA vasculitis usually reveals a normal platelet count, distinguishing it from purpura caused by thrombocytopenia, such as in immune thrombocytopenia.
Routine Investigations
The following tests should be performed to screen for renal involvement
- Urinalysis (on presentation, and frequently over 6 months)
- Blood pressure measurement
Additional Investigations
Biopsies are NOT mandatory and always necessary for the diagnosis of IgA vasculitis:
| Biopsy | Indications | Findings in IgA vasculitis |
|---|---|---|
| Skin biopsy |
|
|
| Kidney biopsy | Indicated if there is severe renal disease
|
Similar to those of IgA nephropathy:
|
Management
Key principles (similar to those of IgA nephropathy):
- Supportive care is the mainstay for most patients
- Analgesia for arthralgia and arthritis
- Ensure adequate hydration
- Appropriate wound care for skin lesions
- ACE inhibitor / ARB for mild renal disease
- Immunosuppressive therapy should NOT be offered routinely, only consider in
- Severe GI bleeding / pain, or
- Severe renal disease (persistent proteinuria / nephrotic syndrome / AKI), or
- Orchitis
Key monitoring tests:
- Frequent urinalysis for 6 months to detect silent nephritis
- Blood pressure measurement (at diagnosis and if nephritis is found)
Prognosis
IgA vasculitis is a self-limiting condition that lasts only a few weeks and resolves completely
~1–2% of children progress to irreversible kidney failure