Henoch-Schönlein purpura (HSP) occurs when the body’s immune system attacks its own cells and organs, inflaming (irritating) blood vessels and causing them to leak.
The immune system naturally creates antibodies to ward off bacteria, viruses and other foreign particles. In children with Henoch-Schönlein purpura (HSP) the antibodies attack blood vessels instead. This causes blood vessels to become inflamed (called vasculitis) and leak blood into the skin and other organs
Inflamed blood vessels cause a rash that looks like small bruises, called purpura, usually seen on the legs and buttocks. HSP can also affect the kidneys, digestive tract and joints.
When these antibodies deposit in the kidneys, they damage the blood vessels there, causing the kidneys to not absorb blood and protein to build up in urine.
The most common and noticeable symptom of HSP is a rash that looks like small bruises, typically on the legs or buttocks. Other symptoms include:
The exact cause of HSP has not been identified. Several factors can trigger the immune response that leads to HSP: