Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Polyarteritis Nodosa (PAN)

(Polyarteritis; Periarteritis Nodosa)


Alexandra Villa-Forte

, MD, MPH, Cleveland Clinic

Reviewed/Revised May 2022 | Modified Sep 2022

Polyarteritis nodosa is a form of vasculitis involving inflammation of medium-sized arteries.

  • Any organ can be affected but usually not the lungs.

  • Polyarteritis nodosa can be rapidly fatal or develop gradually.

  • Symptoms vary depending on which organ is affected.

  • Biopsy of an affected organ or arteriography of the blood vessels can confirm the diagnosis.

  • Prompt treatment with a corticosteroid, another drug that suppresses the immune system, or both is effective.

Polyarteritis nodosa most often develops during middle age, usually when people are in their 50s, but it can occur at any age. It is rare.

The kidneys, skin, nerves, joints, muscles, and digestive tract are most commonly affected. The liver and heart are less often affected.

Symptoms of PAN

Polyarteritis nodosa can be mild at first but can worsen rapidly and be fatal within several months, or it can develop gradually as a chronic debilitating disease. Any organ or combination of organs can be affected. However, usually the lungs are not affected. Symptoms depend on which organs are affected and how severely they are affected. Occasionally, only one organ (such as the intestine) or a nerve is affected. At first, people may feel generally ill and tired and have a fever. They may lose their appetite and lose weight. Night sweats and generalized weakness are common symptoms.

Other symptoms occur when the arteries that carry blood to an organ are damaged, and the organ does not receive enough blood to function normally. Thus, symptoms vary depending on the organ that is affected:

Sometimes damage to an organ is irreversible, and some or all of the organ function is lost. A weakened artery may rupture, causing internal bleeding. Problems, such as a heart attack, can occur long after the inflammation has been treated.

Diagnosis of PAN

  • A doctor's evaluation

  • Blood tests

  • Biopsy

  • Arteriography

Polyarteritis nodosa can be difficult to diagnose. Doctors suspect polyarteritis nodosa when people have a certain combination of symptoms and blood test results. For example, doctors may suspect the diagnosis if a previously healthy middle-aged person has various combinations of symptoms such as an unexplained fever, evidence of a certain pattern of nerve damage (such as difficulty raising a foot or bending the wrist), sores on the skin, pain in the abdomen or limbs, joint or muscle pain, or rapidly developing high blood pressure.

To confirm the diagnosis of polyarteritis nodosa, doctors may take a small sample of an affected organ and examine it under a microscope (biopsy) or take x-rays of the blood vessels (arteriography Arteriography Angiography is a type of medical imaging that uses x-rays and a contrast agent to produce images of blood vessels. In angiography, x-rays are used to produce detailed images of blood vessels... read more ). For arteriography, images are recorded after a dye that is visible on x-rays (radiopaque contrast agent) is injected. Sometimes magnetic resonance angiography may be done to check for irregularities such as narrowing and dilations (aneurysms) in the wall of affected arteries. However, magnetic resonance angiography is less likely to confirm the diagnosis than angiography.

Prognosis for PAN

Without treatment, people with polyarteritis nodosa have a less than 15% chance of surviving 5 years. With treatment, people with polyarteritis nodosa have a greater than 80% chance of surviving 5 years. People whose kidneys, digestive tract, brain, or nerves are affected have a poor prognosis.

Treatment of PAN

  • Corticosteroids

  • Other immunosuppressants

  • Treatment of symptoms or underlying cause as necessary

Treatment of polyarteritis nodosa is aimed at preventing damage from developing but often cannot reverse damage that has already occurred. Treatment depends on the severity of the disorder. Any drugs that may have triggered the disorder are stopped.

High doses of a corticosteroid, such as prednisone, can prevent polyarteritis nodosa from worsening and help people feel better. The goal is a symptom-free period (remission). Because many people need long-term treatment with a corticosteroid and because long-term treatment can have significant side effects, doctors reduce the dose once symptoms have subsided.

If the corticosteroid does not reduce the inflammation adequately, drugs that suppress the immune system Overview of the Immune System The immune system is designed to defend the body against foreign or dangerous invaders. Such invaders include Microorganisms (commonly called germs, such as bacteria, viruses, and fungi) Parasites... read more (immunosuppressants), such as cyclophosphamide, may be given with the corticosteroid. Taking a corticosteroid or another immunosuppressant for a long time reduces the body’s ability to fight infections. Thus, people so treated have an increased risk of infections, which may be serious or fatal if not recognized and treated promptly.

Other treatments, such as those used to control high blood pressure, are often needed to prevent damage to internal organs.

People who have hepatitis B are treated with corticosteroids and antiviral drugs.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • Vasculitis Foundation: Provides information for patients about vasculitis, including how to find a doctor, learn about research studies, and join patient advocacy groups

Drugs Mentioned In This Article

Generic Name Select Brand Names
Deltasone, Predone, RAYOS, Sterapred, Sterapred DS
Cyclophosphamide, Cytoxan, Neosar
quiz link

Test your knowledge

Take a Quiz!