Hypersensitivity Vasculitis

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Hypersensitivity Vasculitis is an abnormal immune reaction against small blood vessels. It comes about when the body makes antibodies against a drug or invading microbe, and complexes of these antibodies become deposited in the blood vessel walls. This leads to fever, rash and arthritis, but if the drug or microbe can be eliminated, the reaction will usually disappear on its own.


  • A slightly elevated, purple-red rash over one or more areas of skin. The rash doesn't whiten when pressed.
  • Flat and raised lesions of different sizes over one or more areas of skin
  • Changes in the cells of the small blood vessels that can be seen through a microscope
  • itchy skin eruption
  • fever
  • loss of appetite
  • fatigue

  • Causes:
    The cause of this disease is not clearly understood, but it is thought to be caused by excessive amounts of antigen in the circulatory system.

    An antigen is a foreign substance or protein in the body that can trigger an immune response. This response results in the production of an a protein that is made by white blood cells that tries to combat the antigen.

    Antibody-antigen reaction starts a chain of events culminating in the release of enzymes that cause vessel damage such as blood clots, blood vessel closure, bleeding and tissue death due to lack of blood and oxygen.

    Infection is important in the pathogenesis of some forms of vasculitis. In polyarteritis, 30-50 percent of patients have evidence of hepatitis B or C. Infective endocarditis and drug reactions (sulfas, penicillins, allopurinol) can also be associated with vasculitis.

    There is no specific treatment for this disorder. Most cases disappear without treatment. If symptoms persist, therapy with corticosteroids such as prednisone is usually tried.

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    ...less medical jargon in a 'Quick Glance' format!