Henoch-Schönlein purpura nephritis in children.

Henoch-Schönlein purpura (HSP) is the most common vasculitis in children, in whom prognosis is mostly dependent upon the severity of renal involvement. Nephritis is observed in about 30% of children with HSP. Renal damage eventually leads to chronic kidney disease in up to 20% of children with HSP nephritis in tertiary care centres, but in less than 5% of unselected patients with HSP, by 20 years after diagnosis. HSP nephritis and IgA nephropathy are related diseases resulting from glomerular deposition of aberrantly glycosylated IgA1. Although both nephritides present with similar histological findings and IgA abnormalities, they display pathophysiological differences with important therapeutic implications. HSP nephritis is mainly characterized by acute episodes of glomerular inflammation with endocapillary and mesangial proliferation, fibrin deposits and epithelial crescents that can heal spontaneously or lead to chronic lesions. By contrast, IgA nephropathy normally presents with slowly progressive mesangial lesions resulting from continuous low-grade deposition of macromolecular IgA1. This Review highlights the variable evolution of similar clinical and histological presentations among paediatric patients with HSP nephritis, which constitutes a challenge for their management, and discusses the treatment of these patients in light of current guidelines based on clinical evidence from adults with IgA nephropathy.