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Definition  

Henoch-Schonlein purpura (HSP) is inflammation of the blood vessels in the skin and other body organs. When it involves the skin, it causes a telltale rash. The rash looks like bruising or small dots in the skin, referred to as purpura.

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Causes  

HSP is caused by an abnormal reaction of the immune system. Normally, the immune system marks and attacks foreign items like viruses and bacteria. However, with HSP, the immune system attacks the blood vessels. It is not clear why the immune system attacks the body.

The change in the immune system may be triggered by:

  • Bacterial or viral infections
  • Certain medications
  • Recent exposure to certain vaccines
  • Infection by insect bites

HSP occurs most often after a respiratory infec