IgA vasculitis.

IgA vasculitis (IgAV) is an inflammation of small vessels caused by perivascular deposition of IgA and activation of neutrophils. It may present as systemic vasculitis (IgAV - Henoch-Schönlein purpura) or as a variant restricted to the skin (skin-limited IgAV), while IgA nephropathy presents a variant restricted to the kidneys. Systemic IgAV affects children more frequently than adults (150 to 200 for 1; incidence 1 in 1 million/year). In the latter, disease more often leads to chronic renal disease. The dominant clinical features include round or oval and retiform palpable purpura predominantly on the lower legs, arthralgia or arthritis, gastrointestinal bleeding or pain and glomerulonephritis with mesangial IgA deposits (IgAVN). Pulmonary, cardiac, genital and neurological involvement occurs, but is rare. Immune complexes containing galactose-deficient IgA1 play a pivotal role in the pathophysiology of IgAV; via the Fc alpha receptor (CD89), they induce neutrophilic inflammation around cutaneous vessels and mesangial proliferation and inflammation in the glomerulus. In case of self-limited disease, only symptomatic treatment is recommended. Treatment of severe IgAV, nephritis or gastrointestinal manifestations, is not established, but some studies reported a benefit of corticosteroids, combined with immunosuppressive drugs. Short-term outcome depends on the severity of gastrointestinal manifestations, while long-term prognosis depends on the severity of nephritis.