- Henoch-Schonlein Purpura is a vasculitis primarily affecting small blood vessels.
- Henoch-Schonlein Purpura is mostly seen in children and young adults although all ages can be affected.
- Henoch-Schonlein Purpura is most likely due to vascular deposition of immune complexes composed of IgA and exogenous antigen. The source of the exogenous antigen may be infectious in some cases such as from respiratory infections with Streptococci or may be from ingested foods or drugs. Because of the role of IgA and its post-infectious initiation, Henoch-Schonlein Purpura may be a clinical variant of IgA Nephropathy.