This chapter discusses the Henoch-Schonlein purpura (HSP). HSP is a systemic vasculitis characterized by purpuric skin lesions unrelated to any underlying coagulopathy, abdominal pain, and gastrointestinal bleeding, joint manifestations, and renal involvement. The classic clinical triad of HSP is palpable purpura, joint symptoms, and abdominal pain. However, renal involvement is the most serious
... [Show full abstract] complication. HSP is characterized histologically by infiltration of the small blood vessels with polymorphonuclear leukocytes and the presence of leukocytoclasia. Immunofluorescence staining usually reveals the presence of IgA-dominant immune deposits in the walls of the small vessels and in the renal glomeruli. Mesangial deposition of nephritis-associated plasmin receptor, a group-A streptococcal antigen, has been detected in the glomeruli of children with HSP and nephritis. HSP is the most common vasculitis in children and an infrequent condition in adults. The annual incidence in children ranges between 125 and 180 cases per million.
