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Polyarteritis nodosa (PAN)

What is polyarteritis nodosa?

Polyarteritis nodosa (PAN) is a very rare form of vasculitis involving predominantly medium-sized blood vessels. Inflammation of the blood vessels may cause segments of vessels to weaken and stretch, resulting in an aneurysm (weakening of the vessel wall). Inflammation of the vessel wall can also lead to thickening and subsequent partial blockage (stenosis) or complete blockage (occlusion) of the artery. These aneurysms and blockages can result in the surrounding tissues being deprived of an adequate blood supply. The disease commonly affects the intestines, kidneys, skin, and peripheral nervous system but can affect most parts of the body. As is true of other forms of vasculitis, how PAN affects the body differs widely from patient to patient.

Who gets polyarteritis nodosa?

People between the age of 40 years and 60 years are most often affected. Men may be affected more than women. In most cases, we do not know why people get PAN. Some cases of PAN occur in patients with chronic infection with the hepatitis B virus.

What causes polyarteritis nodosa?

PAN is thought to be an auto-immune disease for which there is no known cause in most cases. There is an important known association between infection with hepatitis B or hepatitis C viruses and development of PAN. However, only a small fraction of patients infected with these viruses develop PAN.

How is polyarteritis nodosa diagnosed?

The diagnosis of PAN is made by combining clinical features with the results of angiograms and tissue biopsies.

What is the treatment for polyarteritis nodosa?

Treatment of PAN almost always involves use of glucocorticoids in high doses that are slowly reduced over many months. Often an immunosuppressive drug such as cyclophosphamide, methotrexate, or azathioprine, is added to the glucocorticoid therapy. If diagnosed early, treatment can bring about early remission and prevent organ failure. Unfortunately, while remission is usually achieved, relapses do occur.

What are the chances that my newly diagnosed vasculitis will relapse?

Reported relapse rates in polyarteritis nodosa have ranged from 10-30%.

What is the difference between systemic polyarteritis nodosa (PAN) and cutaneous PAN?

Polyarteritis nodosa (PAN) is a vasculitis affecting medium-sized blood vessel. In patients with "cutaneous polyarteritis nodosa", the findings of the disease are localized to the skin (purpura or subcutaneous nodules), but also sometimes the peripheral nerve(s) of the same limb (causing weakness and/or numbness). Patients with systemic polyarteritis nodosa have involvement of other organs, including the gastrointestinal tract, heart and/or kidney. The systemic form is therefore usually most severe and requires stronger treatment.