Henoch-Schönlein Purpura (Anaphylctoid purpura)
Immune complex mediated disease contain IgA within capillaries of skin, GI and renal involvement.Incidence:
- HSP is the commonest generalized vasculitis of childhood.
- HSP is the commonest cause of non-thrombocytopenic purpura in children.
- Can occur at any age but peaking at 3–10 years of age.
- Male : female = 2:1
- Peaks during the winter months.
- It is postulated that genetic predisposition and antigen exposure increase circulating IgA levels and disrupt IgG synthesis.
-The IgA and IgG interact to produce complexes that activate complement and are deposited in affected organs, precipitating an inflammatory response with vasculitis.
- Antigen may be:
- Infections (e.g. Group A ß hemolytic streptococci or ohers)
- Insect bites
- Drugs or food allergy.
- IgA-mediated vasculitis of small blood vessels with IgA deposits seen in these vessels, primarily those of the skin and intestine.
- Deposition of polymeric immunoglobulin A (IgA) in glomeruli.
- IgA deposits are present by immunofluorescence,
- Broad spectrum of glomerular lesions that can range from mild proliferation to necrotic and crescentic changes can be seen
