What is vasculitis?

Vasculitis is the inflammation of the body’s blood vessels. Vasculitis can affect very small blood vessels (capillaries), medium-size blood vessels, or large blood vessels such as the aorta (the main blood vessel that leaves the heart).

When inflamed, the blood vessels may become weakened and stretch in size, which can lead to aneurysms. The vessels also may become so thin that they rupture resulting in bleeding into the tissue. Vasculitis can also cause blood vessel narrowing to the point of closing off entirely (called an occlusion). If blood flow in a vessel with vasculitis is reduced or stopped, the tissues that receive blood from that vessel become injured and begin to die.

What causes vasculitis?

In most cases, the exact cause is unknown; however, it is clear that the immune system (the system that keeps the body healthy) plays a big role. While the immune system usually works to protect the body, it can sometimes become "overactive" and end up attacking parts of the body. In most cases of vasculitis, something causes an immune or "allergic" reaction in the blood vessel walls. Substances that cause allergic reactions are called antigens. Sometimes certain medicines or illnesses can act as antigens and start this process.

What are the symptoms of vasculitis?

Common symptoms include:

Additional symptoms can occur, depending on the area of the body affected by vasculitis. If a blood vessel in the skin with vasculitis is small, the vessel may break and produce tiny areas of bleeding in the tissue. These areas will appear as small red or purple dots on the skin. If a larger vessel in the skin is inflamed, it may swell and produce a nodule (lump or mass of tissue), which may be felt if the blood vessel is close to the skin surface.

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