What is Polyarteritis Nodosa?
Polyarteritis nodosa (PAN) is a type of vasculitis that mainly affects medium-sized arteries. Vasculitis includes a group of diseases where your immune system attacks the blood vessels and results in inflammation. Inflammation of the arteries can lead to narrowing or blockage of blood vessels, causing a lack of blood supply to affected body tissues. However, inflammation can also result in thinning of the blood vessel walls and aneurysm formation (dilation of the blood vessel) which can sometimes rupture. In some cases, PAN can be caused by chronic hepatitis B virus infection. In most cases, no cause is found (idiopathic). PAN most commonly affects the skin, nerves, gut or kidney arteries. Some forms of PAN affect only the skin (cutaneous PAN) or one body organ (localized PAN), while in other cases, the disease affects multiple organ systems (systemic PAN).
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.
PAN mainly affects the medium-sized arteries in the body. The symptoms of PAN depend on the arteries and body tissues that are affected. Symptoms vary from person to person and not all symptoms are present in everyone with the diagnosis.
Symptoms may include:
- feeling tired
- decreased appetite
- rapid and sudden weight loss
- skin rash or sores
- muscle aches
- joint pain
- abdominal pain
- blood in the stool
- flank pain
- testicular pain in men
- chest pain
- difficulty breathing
- difficult to treat hypertension (high blood pressure)
- numbness or tingling of the hands or feet
- sudden loss of strength in the hands or feet
There is no specific test to diagnose PAN. The diagnosis of PAN is based on symptoms, physical examination, laboratory tests and specialized imaging studies. Since PAN often affects the blood vessels that supply the gut and kidneys, an angiogram (dye-based study of the blood vessels) may be needed to make the diagnosis. This may show areas of narrowing of the blood vessels (stenosis) or aneurysms. CT or MRI scans with dye may also be useful to look for changes in blood vessels and internal organs. In some cases of PAN, a tissue biopsy may be necessary for diagnosis.
In cases of PAN related to Hepatitis B, treatment often consists of glucocorticoids (steroids), anti-viral medications and sometimes plasma exchange. For the idiopathic form of PAN, treatment consists of glucocorticoids (steroids, such as prednisone) and immunosuppressive medications that are used to suppress the immune system. These may include a chemotherapy (cyclophosphamide) or other medications such as methotrexate or azathioprine. This depends on the clinical situation.
There is no cure for PAN but the disease and its symptoms can be managed. The long-term prognosis depends on the severity of the organs involved.
The goal of treatment is to prevent further progression and damage from the disease. Most people do well with treatment but relapses can occur. Patients require close follow-up with their doctors with periodic monitoring of the disease activity which is done based on symptoms and laboratory evaluations. In addition to monitoring for disease relapses, patients also need to be monitored for side-effects or complications from the treatment.
What’s new in Polyarteritis Nodosa?
Forms of vasculitis like PAN are uncommon and likely under recognized. The symptoms can be non-specific and can result in delayed diagnosis. People suspected of having PAN should be evaluated and treated in specialized centers with experience in the management of vasculitis.
Prevention of Hepatitis B infection by vaccination appears to have lowered the number of new cases of PAN due to Hepatitis. Newer medications that treat chronic viral infections have been useful in the treatment of PAN related to Hepatitis B.
Observational cohorts of patients with PAN (where patients are followed long-term) have provided us with invaluable information on the prognosis and long-term complications of therapy. Clinical trials through multi-center and international collaborations continue to provide us with insights on how to treat this disease.
Given the significant side-effects of current treatments, researchers continue to look for better and safer medications. This remains an area of active research. Other areas of research include the pathogenesis of this condition, biomarkers and prognostic markers that may help follow patients over time.
Revision: September 2012