What is polyarteritis nodosa?

Polyarteritis nodosa is a autoimmune disease (immune system attacking its own body) featuring inflammation of the arteries (arteritis). As arteries are involved, the disease can affect any organ of the body. The most common areas of involvement include the muscles, joints, intestines (bowels), nerves, kidneys, and skin. Strokes, heart attacks can happen. Poor function or pain in any of these organs can be a symptom. Poor blood supply to the bowels can cause abdominal pain, local bowel death, and bleeding. Fatigue, weight loss, and fever are common.

Polyarteritis nodosa is most common in middle age persons. Its cause is unknown, but it has been reported after Hepatitis B or C infection.

How is polyarteritis nodosa diagnosed?

The diagnosis is confirmed by tests that indicate inflammation including elevation of blood sedimentation rate and c-reactive protein. The white blood cell count and platelet count can be elevated, while the red blood count is decreased (anemia). The Hepatitis B virus tests (antigen and antibody) can be found in 10-20% of patients. Urine testing can show protein and red blood cells in the urine. In patients with nerves affected, nerve function tests are abnormal.

The diagnosis of polyarteritis nodosa is confirmed by a biopsy of involved tissue that reveals the inflamed blood vessels (vasculitis). Examples of tissues that are sometimes biopsied include nerves, muscle, kidneys, and bowel. The vasculitis of the bowel and kidneys can often be detected with an angiogram (x- ray testing while contrast "dye" is infused into the blood vessels).

The American College of Rheumatology established criteria for the classification of polyarteritis nodosa in 1990. For classification purposes, a patient is said to have polyarteritis nodosa if at least 3 of the following 10 criteria are present:

Weight loss greater than/equal to 4 kg.
Livedo reticularis (a mottled purplish skin discoloration over the extremities or torso).
Testicular pain or tenderness. (occasionally, a site biopsied for diagnosis).
Muscle pain, weakness, or leg tenderness.
Nerve disease (either single or multiple).
Diastolic blood pressure greater than 90mmHg (high blood pressure).
Elevated kidney blood tests (BUN greater than 40 mg/dl or creatinine greater than 1.5 mg/dl).
Hepatitis B virus tests positive (for surface antigen or antibody).
Arteriogram (angiogram) showing the arteries that are dilated (aneurysms) or constricted by the blood vessel inflammation.
Biopsy of tissue showing the arteritis (typically inflamed arteries).

How is polyarteritis treated?

Polyarteritis is a serious illness that can be fatal. Treatment is directed toward decreasing the inflammation of the arteries by suppressing the immune system. Medications used to treat polyarteritis nodosa include high-dose intravenous and oral cortisone medications, such as prednisone as well as immunosuppressive drugs, such as cyclophosphamide (Cytoxan) or azathioprine (Imuran).

When hepatitis B is present in patients with polyarteritis, antiviral medications (such as vidarabine and interferon-alpha). Some studies have used various combinations of antiviral medications, plasma exchange, and immunosuppressive drugs.




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