Henoch-Schönlein purpura. A multisystem disease also seen in adults.

Henoch-Schönlein purpura is a common vasculitic syndrome of childhood that is also seen in adults. It is characterized by the deposition of immune complexes, mainly IgA and C3, in various organ systems. Diagnosis is based on the presence of nonthrombocytopenic purpura, arthritis or arthralgia, abdominal pain that may be complicated by intussusception, and glomerulonephritis. The disease is usually self-limited and lasts a few weeks but may recur. Recovery is complete in almost all patients, with the severity of renal involvement dictating any remaining sequelae. Corticosteroid therapy may provide acute symptomatic relief but apparently has no effect on the natural course of the disease.