Henoch-Schönlein purpura.

@article{Duquesnoy1991HenochSchnleinP,
  title={Henoch-Sch{\"o}nlein purpura.},
  author={Bernard Duquesnoy},
  journal={Bailliere's clinical rheumatology},
  year={1991},
  volume={5 2},
  pages={253-61}
}
Henoch-Schönlein purpura probably results from a reaction in a host sensitized by an infective stimulus. This stimulus leads to the synthesis of IgA antibody, the presence of circulating immune complexes and a leukoclastic vasculitis involving IgA resulting in renal and dermatological manifestations. The risk factors, the causal organism and the reason for the association with IgA nephropathy remain unknown.