IgA vasculitis - similarities and differences to IgA nephropathy Abstract. IgA vasculitis (IgAV), formerly called Henoch-Schönlein Purpura (HSP) is an immune complex-mediated vasculitis of small vessels typically affecting the skin, gastrointestinal tract, and the kidneys. Based on distinct histopathological and pathophysiological commonalities of IgAV and IgA nephropathy (IgAN) they are viewed as part of a spectrum of IgA-mediated inflammatory syndromes. While the disease course in children is most often benign, IgAV has a high risk of renal and gastrointestinal complications when first appearing in adulthood. Acute morbidity and mortality in IgAV are determined by gastrointestinal complications such as intussusception or perforation, while chronic morbidity depends on renal involvement. Nephritis symptoms can appear, subclinically, many weeks after the initial manifestation of IgAV, and can therefore be missed. Continuous monitoring of renal parameters and blood pressure is therefore recommended even after apparent remission of the disease. As there are no data from randomized controlled trials available, the treatment of IgAV is currently based on consensus-based expert opinions.