Definition and epidemiology
Henoch-Schönlein purpura (HSP), now termed IgA vasculitis (IgAV), is the commonest systemic vasculitis of childhood — a small-vessel, immune-complex (IgA1-dominant) leukocytoclastic vasculitis. Annual incidence is roughly 10–20 per 100,000 children, with peak onset at 4–6 years and a slight male predominance. About 90% of cases occur in children, often 1–3 weeks after an upper respiratory infection (group A streptococcus among the implicated triggers), with autumn–winter clustering.
It is usually a self-limiting illness lasting 4–6 weeks, but up to a third relapse, and the kidney determines long-term prognosis.
Clinical features
The classic tetrad:
- Palpable purpura — the mandatory feature, present in 95–100%. Symmetrical, non-thrombocytopenic, gravity-dependent (buttocks and lower limbs), and may be preceded by a maculopapular or urticarial phase.
- Arthritis/arthralgia (~75%) — oligoarticular, large joints (ankles, knees), transient and non-erosive.
- Abdominal pain (~50–75%) — colicky; may precede the rash. Bowel-wall oedema and haemorrhage can cause GI bleeding and, importantly, intussusception (typically ileo-ileal).
- Renal involvement (~20–60%) — ranging from isolated microscopic haematuria to nephritic/nephrotic syndrome. Usually appears within 4–6 weeks of onset but can be delayed up to 6 months.
Scrotal involvement (orchitis) can mimic testicular torsion. Subcutaneous oedema of the scalp, hands and feet is common in younger children.
Diagnosis
HSP is a clinical diagnosis. The validated EULAR/PRINTO/PRES (Ankara 2008) classification criteria require purpura or petechiae with lower-limb predominance (mandatory) plus at least one of: diffuse abdominal pain, arthritis/arthralgia, renal involvement (haematuria/proteinuria), or a biopsy showing leukocytoclastic vasculitis or proliferative GN with predominant IgA deposition — sensitivity ~100%, specificity ~87%. Atypical distribution or features warrant skin/renal biopsy and exclusion of mimics (meningococcaemia, ITP, HUS, ANCA vasculitis, acute haemorrhagic oedema of infancy).
See the full criteria: Henoch-Schönlein Purpura (IgA Vasculitis)
Red flags
- Purpura above the waist, atypical distribution, or any thrombocytopenia (reconsider the diagnosis)
- Severe colicky abdominal pain, bilious vomiting, GI bleeding — suspect intussusception (urgent ultrasound)
- Hypertension, oedema, nephrotic-range proteinuria, or rising creatinine — nephritis
- Acute scrotal pain — exclude torsion
- Altered consciousness, seizures, pulmonary haemorrhage — rare severe organ involvement
Management overview
Most children need only supportive care: rest, hydration, and analgesia. NSAIDs help arthralgia but are avoided with significant renal involvement or GI bleeding. Corticosteroids (oral prednisolone, or IV methylprednisolone in severe disease) are reserved for significant GI involvement (severe pain, bleeding), orchitis, or severe nephritis — they do not prevent nephritis and should not be used prophylactically. Significant or progressive HSP nephritis is managed with steroids ± immunosuppression (e.g. mycophenolate, cyclophosphamide) per SHARE recommendations, with pediatric nephrology referral.
The key to follow-up is renal surveillance: blood pressure and urinalysis at diagnosis and regularly for 6–12 months, even after the rash resolves, because nephritis can be delayed. Persistent proteinuria mandates nephrology referral.
References
- Ozen S, et al. EULAR/PRINTO/PRES Ankara 2008 criteria. Ann Rheum Dis. 2010;69:798–806.
- Ozen S, et al. SHARE recommendations for IgA vasculitis. Rheumatology. 2019;58:1607–1616.
- Nelson Textbook of Pediatrics, 21st ed.
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.