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IgA vasculitis (Henoch-Schönlein purpura)
IgA vasculitis is the commonest vasculitis of childhood: palpable purpura on the legs and buttocks with a normal platelet count, usually with joint and abdominal pain; most cases settle on their own, and follow-up exists to catch kidney involvement.
Why it matters in the exam
The typical question describes a school-age child, after an upper respiratory infection, with a palpable purple rash on the legs, knee pain and abdominal pain. The candidate must recognise that normal platelets separate it from ITP and leukaemia, know that the dangerous abdominal complication is intussusception (usually ileo-ileal, diagnosed by ultrasound), and remember that the long-term prognosis depends on the kidney.
Treatment in most cases is supportive: rest, analgesia and NSAIDs for joint pain when the kidney is not involved. Steroids relieve severe abdominal pain but do not prevent nephritis — a common distractor. Urinalysis and blood-pressure follow-up continue for at least 6 months, and nephritis with significant proteinuria or falling kidney function is referred to a nephrologist.
The diagnosis is clinical in most cases: palpable purpura plus at least one of abdominal pain, joint pain or arthritis, kidney involvement or IgA deposits on a biopsy. A skin biopsy is needed only when the picture is atypical, and a kidney biopsy — when there is significant proteinuria, falling kidney function or a nephrotic syndrome. About a third of children have a recurrence of the rash in the first months, usually milder. In adults the disease is rarer, but kidney involvement is more common and more severe, so in internal medicine exams it is asked in a kidney context.
Key points
- The commonest vasculitis of childhood; usually after a respiratory infection.
- Palpable purpura on the legs with normal platelets.
- Joints, gut and kidney; intussusception is the abdominal complication.
- Supportive treatment; steroids for severe abdominal pain, not to prevent nephritis.
- Urine and blood-pressure follow-up for at least 6 months.
Summary table
| System | Manifestation | What to do |
|---|---|---|
| Skin (required for diagnosis) | Palpable purpura mainly on the lower limbs and buttocks | Blood count and smear: normal platelets |
| Joints | Pain or arthritis of the knees and ankles, without lasting damage | Analgesia; NSAIDs if the kidney is normal |
| Gut | Colicky abdominal pain, blood in the stool; intussusception | Abdominal ultrasound; steroids for severe pain |
| Kidney | Haematuria and proteinuria; rarely nephrotic or nephritic syndrome | Urinalysis and blood pressure for at least 6 months; nephrologist if proteinuria is significant |
| Other | Orchitis, oedema of the scalp and the back of the hands | Supportive |
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Sources
- EULAR/PRINTO/PRES criteria for Henoch-Schönlein purpura (IgA vasculitis), 2010 — Classification criteria
- SHARE European consensus-based recommendations for the diagnosis and treatment of IgA vasculitis, 2019 — Diagnosis, kidney involvement and treatment
- Nelson Textbook of Pediatrics, 22nd edition (2024) — IgA Vasculitis (Henoch-Schönlein Purpura)
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.