Vasculitis is a condition where the blood vessels in the body become inflamed. Blood vessels are the tubes that carry blood throughout the body, and inflammation in these vessels can cause a range of problems. When blood vessels are inflamed, it can make them narrower, which can reduce blood flow to organs and tissues, potentially causing damage.

There are different types of vasculitis, and the disease can affect blood vessels of any size—small, medium, or large. Some types of vasculitis only affect certain parts of the body, like the skin or lungs, while others can affect organs such as the kidneys, heart, and brain.

The main symptoms of vasculitis depend on which part of the body is affected, but common symptoms include:

• Fever: Often an early sign of inflammation in the body.
• Fatigue: Feeling very tired, even after resting.
• Weight loss: Unexplained weight loss is another common symptom.
• Pain: Pain in the affected area, such as joints, muscles, or organs, depending on where the inflammation is.
• Rashes: In some types of vasculitis, a rash may appear on the skin.
• Numbness or weakness: If blood flow to the nerves is affected, it can cause numbness or weakness in the arms or legs.

There are many types of vasculitis, and they are often grouped based on the size of the blood vessels they affect. Some examples include:

1. Small vessel vasculitis: This type affects the smaller blood vessels and can cause problems in the skin, kidneys, and nerves. An example of this is Granulomatosis with polyangiitis (formerly called Wegener's granulomatosis).

2. Medium vessel vasculitis: This affects the medium-sized blood vessels, such as the arteries, and can impact organs like the skin, digestive system, or kidneys. Polyarteritis nodosa is an example of this type.

3. Large vessel vasculitis: This affects the large blood vessels, like the aorta, and can cause problems in organs like the heart or brain. Giant cell arteritis is an example of large vessel vasculitis.

Vasculitis can be caused by a variety of factors, including:

• Autoimmune diseases: The immune system mistakenly attacking healthy blood vessels.
• Infections: Certain infections can trigger vasculitis.
• Medications: Some drugs can cause vasculitis as a side effect.
• Genetic factors: Some people may be more prone to vasculitis due to their genetic makeup.

The diagnosis of vasculitis typically involves blood tests, imaging studies, and sometimes a biopsy of the affected tissue.

Treatment for vasculitis generally focuses on reducing inflammation and suppressing the immune system to prevent further damage. Medications like corticosteroids (e.g., prednisone) and other immunosuppressive drugs are commonly used. In severe cases, hospitalization or additional treatments might be required.

While vasculitis can be a serious condition, with prompt diagnosis and treatment, many people can manage the disease and prevent complications. The outlook depends on the specific type of vasculitis, the organs affected, and how quickly treatment is started.