Vasculitis refers to a varied group of disorders which all share a common underlying problem of inflammation of a blood vessel or blood vessels. The inflammation may affect any size blood vessel, anywhere in the body. It may affecteither arteries and/or veins. The inflammation may be focal, meaning that itaffects a single location within a vessel; or it may be widespread, with areas of inflammation scattered throughout a particular organ or tissue, or evenaffecting more than one organ system in the body.
Inflammation is a process which occurs when the immune system of the body responds to either an injury or a foreign invader (virus, bacteria, or fungi). The immune system response involves sending a variety of cells and chemicals to the area in question. Inflammation causes blood vessels in the area to leak, causing swelling. The inflamed area becomes red, hot to the touch, and tender.
Antibodies are immune cells which recognize and bind to specific markers (called antigens) on other cells (including bacteria and viruses). These antibody-antigen complexes can then stimulate the immune system to send a variety ofother cells and chemicals involved in inflammation to their specific location.
Some researchers believe that the damaging process of vasculitis is kicked off by such antibody-antigen complexes. These complexes are deposited along thewalls of the blood vessels. The resulting inflow of immune cells and chemicals causes inflammation within the blood vessels.
The type of disease caused by vasculitis varies depending on a number of factors:
- The organ system or tissue in which the vasculitis occurs
- The specific type of inflammatory response provoked
- Whether the affected vessels are veins (which bring blood to the heart) or arteries (whichcarry blood and oxygen from the heart to the organs and tissues)
- Thedegree to which blood flow within the affected vessel is reduced.
Some types of vasculitis appear to be due to a type of allergic response to aspecific substance (for example, a drug). Other types of vasculitis have noidentifiable initiating event. Furthermore, researchers have not been able toconsistently identify antibody-antigen complexes in all of the types of diseases caused by vasculitis. The types of antigens responsible for the initialimmune response have often gone unidentified as well. Furthermore, not all people with such complexes deposited along the blood vessels go on to develop vasculitis. Some researchers believe that, in addition to the presence of immune complexes, an individual must have some other characteristics which make him or her susceptible to vasculitis. Many questions have yet to be answered to totally explain the development these diseases.
Symptoms of vasculitis depend on the severity of the inflammation and the organ system or systems affected. Some types of vasculitis are so mild that theonly symptoms noted are small reddish-purple dots (called petechiae) on the skin due to tiny amounts of blood seeping out of leaky blood vessels. In morewidespread types of vasculitis, the patient may have general symptoms of illness, including fever, achy muscles and joints, decreased appetite, weight loss, and loss of energy. The organ systems affected by vasculitis may include:
- The skin
- The joints
- The gastrointestinal system
- The heart
- The lungs
- The kidneys
Multiple types of disease are associated with vasculitis. Many autoimmune diseases have vasculitis as one of their complications. These include systemic lupus erythematosus, rheumatoid arthritis, scleroderma, and polymyositis. Other types of diseases which have vasculitis as their major manifestations include:
- Polyarteritis nodosa
- Kawasaki's disease
- Henoch-Schonlein purpura
- Serum sickness
- Temporal arteritis (also calledgiant cell arteritis)
- Takayasu's arteritis,
- Wegener's granulomatosis
Diagnosis of any type of vasculitis involves demonstrating the presence of astrong inflammatory process. Tests which reveal inflammation throughout the body include erythrocyte sedimentation rate, blood tests which may reveal anemia and increased white blood cells, and tests to demonstrate the presence ofimmune complexes and/or antibodies circulating in the blood. An x-ray procedure, called angiography, involves injecting dye into a major artery, and thentaking x-ray pictures to examine the blood vessels, in order to demonstrate the presence of inflammation of the vessel walls. Tissue samples (biopsies) may be taken from affected organs to demonstrate inflammation.
Even though there are many different types of vasculitis, with many differentsymptoms based on the organ system affected, treatments are essentially thesame. They all involve trying to decrease the activity of the immune system.Steroid medications (like prednisone) are usually the first types of drugs used. Steroids work by interfering with the chemicals involved in the inflammatory process. More potent drugs for severe cases of vasculitis have more serious side effects. These include drugs like cyclophosphamide. Cyclophosphamideworks by actually killing cells of the patient's immune system.
The prognosis for vasculitis is quite variable. Some mild forms of vasculitis, such as those brought on by reactions to medications, may resolve totally on their own and not even require treatment. Temporal arteritis, serum sickness, Henoch-Schonlein purpura, and Kawasaki's disease usually have excellent prognoses, although when Kawasaki's affects the heart, there is a high death rate. Other types of vasculitis were always fatal, prior to the availability ofprednisone and cyclophosphamide, and continue to have high rates of fatal complications. These include polyarteritis nodosa and Wegener's granulomatosis.
Because so little is known about what causes a particular individual to develop vasculitis, there are no known ways to prevent it.