Henoch-Schönlein purpura (HSP), also called IgA vasculitis (IgAV) , is the most common form of systemic vasculitis in children. Ninety percent of cases occur in the pediatric age group. In contrast to many other forms of systemic vasculitis, HSP (IgAV) is self-limited in the great majority of cases. The disease is characterized by a tetrad of clinical manifestations:
- Palpable purpura in patients with neither thrombocytopenia nor coagulopathy
- Abdominal pain
- Renal disease
The clinical manifestations, pathogenesis, diagnosis, and differential diagnosis of HSP (IgAV) will be presented here. The management of HSP (IgAV) and a more complete discussion of the renal manifestations of HSP (IgAV) are found elsewhere. (See "Management of Henoch-Schönlein purpura (IgA vasculitis)" and "Renal manifestations of Henoch-Schönlein purpura (IgA vasculitis)".)
HSP (IgAV) is primarily a childhood disease that occurs between the ages of 3 and 15 years. In a population-based study from the United Kingdom, the annual incidence was about 20 per 100,000 in children <17 years of age with a peak incidence of 70 per 100,000 in children between the ages of four and six years . In reports from Taiwan and the Czech Republic, there was a lower incidence of 10 per 100,000 in children <17 years of age with a peak incidence at five to seven years of age [3,4]. Although there are no comparable epidemiologic data, HSP (IgAV) is less common in adults . The rate of HSP (IgAV) is significantly higher (approximately 5 percent) in patients with familial Mediterranean fever [6,7].
There is a male predominance with reported male-to-female ratios of 1.2:1 to 1.8:1 [2,3,8,9]. HSP (IgAV) is seen less frequently in black compared to white or Asian children .