Henoch-Schonlein Purpura (HSP) is the most common vasculitis of childhood. It occurs in all age groups but is most common in younger children with 50% presenting in the under 5y group and 75% in the under 10y group. Its cause is unknown, but appears to be a mix of immune, genetic and environmental factors.
In HSP the rash is typically of palpable purpura distributed over the extensor surfaces of the lower limbs and buttocks. The arms, face and ears may be involved but the trunk is usually spared. The purpura range from large petechiae to large bruises.
Diagnosis is based on consensus criteria by the European League Against Rheumatism (EULAR) and Paediatric Rheumatology European Society (PReS) which states that classification of HSP can be made on the finding of palpable purpura (mandatory) in the presence of at least one of the following four features:
- Diffuse abdominal pain
- Arthritis (acute) or arthralgia
- Renal involvement (any haematuria and/or proteinuria)
- Any biopsy showing predominant IgA deposition
Rash is commonly the presenting symptom and this often after a respiratory infection. Other system involvement may be present from the onset or may evolve over days or weeks. These may include gastrointestinal or joint pain, renal involvement with proteinuria/nephrotic syndrome/nephritis/renal impairment, and less commonly neurological or pulmonary involvement.
Diagnosis is made clinically, with investigations aimed at evaluating the involvement of other organs. Initial investigations usually include a full blood count, clotting, urea, electrolytes and creatinine, liver and bone profile and urinalysis to identify haematuria and proteinuria.
HSP is a self-limiting condition but a third of patients have recurrence of symptoms. Longer term prognosis is predominantly related to the renal disease. Those with nephrotic syndrome, renal impairment and hypertension at presentation are likely to have a poorer outcome.
The use of prednisolone has not been shown to make clinically important improvements in the rate of long-term renal complications. It has been shown to reduce the duration of abdominal and joint pain and may reduce the risk of abdominal complications. It may be considered for use in patients with more than mild joint or abdominal pain.
Tizard EJ, Hamilton-Ayres MJJHenoch–Schönlein purpuraArchives of Disease in Childhood – Education and Practice 2008;93:1-8.https://dx.doi.org/10.1136/adc.2004.066035