Information on the following diseases can be found in the Related Disorders section of this report:

• microscopic polyangiitis
• Wegener's granulomatosis
• Churg-Strauss syndrome
• Takayasu`s arteritis
• giant cell arteritis
• Cogan's syndrome

Polyarteritis nodosa mainly affects small and medium-sized arteries. Blood vessels in any organ or organ system may be affected, including arteries supplying the kidneys, heart, intestine, nervous system, and/or skeletal muscles. Damage to affected arteries may result in abnormally increased blood pressure (hypertension), "ballooning" (aneurysm) of an arterial wall, the formation of blood clots (thrombosis), obstruction of blood supply to certain tissues, and/or tissue damage and loss (necrosis) in certain affected areas. Joint, muscle, abdominal and testicular pain may occur. The small and medium-sized arteries of the kidneys are most often involved. The lungs are much less commonly affected.

The exact cause of polyarteritis nodosa is not known. In the majority of patients no predisposing cause has been found. Unidentified bacterial and/or viral infections may be a cause. Polyarteritis nodosa has been observed in drug abusers, particularly those using amphetamines, and in patients with hepatitis B (infection of the liver). (For more information on this disorder, choose "Hepatitis B" as your search term in the Rare Disease Database.) This disorder has also been linked to an allergic reaction to some drugs and vaccines.

Most scientists believe that polyarteritis nodosa is an autoimmune disease. Autoimmune disorders are caused when the body's natural defenses against "foreign" or invading organisms (e.g., antibodies) begin to attack healthy tissue for unknown reasons. Recent research suggests that a bacterial infection may initially trigger onset of polyarteritis nodosa causing an abnormal immune response to infection. Treatment of polyarteritis nodosa usually involves drugs that alter the immune system.

Polyarteritis nodosa usually affects people between 40 and 50 years of age, but it may occur in any age group. It affects approximately 1 in 100,000 people. Men appear to be affected two to three times more often than women.

Symptoms of the following disorders can be similar to those of polyarteritis nodosa. Comparisons may be useful for a differential diagnosis:

Microscopic polyangiitis (formerly known as microscopic polyarteritis) can have inflammation of arteries that is clinically and pathologically indistinguishable from polyarteritis nodosa, but, unlike polyarteritis nodosa, this form of systemic vasculitis also has inflammation of vessels smaller than arteries, including arterioles, capillaries and venules. This small vessel involvement often involvers the venules in the skin (causing hemorrhage called purpura), capillaries in the lungs (causing pulmonary hemorrhage) and capillaries in the filters of the kidneys (causing glomerulonephritis). Microscopic polyangiitis is closely related to Wegener's granulomatosis and Churg-Strauss syndrome; and all three are associated with anti-neutrophil cytoplasmic autoantibodies (ANCA) in the blood.


Wegener's granulomatosis occurs in the 4th or 5th decade of life and has a slight male preponderance. It typically involves the upper and lower respiratory tracts and kidney. This disorder usually progresses into a generalized inflammation of the blood vessels and kidney. (For more information on this disorder, choose "Wegener" as your search term in the Rare Disease Database.)

Churg-Strauss syndrome is a lung disorder often occurring as a complication of other disorders that affect the arteries. Allergenic blood vessel inflammation, (angiitis or vasculitis), is usually accompanied by many inflammatory nodular lesions. (For more information on this disorder, choose "Churg-Strauss" as your search term in the Rare Disease Database.)

Takayasu arteritis (aortic arch syndrome) is an inflammation of the walls of large and mid-sized arteries followed by fibrosis and thickening. It affects mainly women. (For more information on this disorder, choose "Takayasu" as your search term in the Rare Disease Database.)

Giant cell arteritis is a disease that affects the large arteries and occasionally the small ones. Cranial arteries are often affected causing headaches, and scalp tenderness. (For more information on this disorder, choose "Giant Cell Arteritis" as your search term in the Rare Disease Database.)

Cogan's syndrome is a very rare polyarteritis-type disorder. It is characterized by interstitial keratitis, vertigo, tinnitus, and hearing loss. This is often associated with other systemic disease symptoms such as: congestive heart failure, intestinal hemorrhage, enlarged spleen, high blood pressure, and muscle and bone symptoms. Treatment may consist of the use of corticosteroid drug therapy and when started early in the disease can result in clearing of inflamed eyes and in hearing recovery. Other symptoms may respond to treatment specific to that disorder. Cogan's syndrome can occur at any age and affects men and women equally.

Diagnosis
Since there are no blood or other chemical tests to indicate the presence of this disorder, the diagnosis is based upon physical examination and the exclusion of other likely candidates for diagnosis. In suspected cases, biopsy of the blood vessel wall (lumen) is necessary to confirm the presence of the typical lesions. Biopsies of the kidney or liver may also be required.

Treatment
Treatment of polyarteritis nodosa usually consists of the use of corticosteroid drugs, such as prednisone, to suppress the immune system and relieve inflammation. Cyclophosphamide has also been used for this purpose. Treatment for control of hypertension may also be indicated. Surgical intervention is sometimes required in cases of gastrointestinal involvement. Other treatment is symptomatic and supportive.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.

For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com

A study has been listed on the Clinical Trials web site of the possible use of autologous peripheral blood stem cell transplantation in patients with life-threatening autoimmune diseases such as polyarteritis nodosa. At the present time, patients are not being recruited for that study.

Other information about current research may be available from the following resource:

Johns Hopkins Vasculitis Center
Bayview Medical Center
5501 Hopkins Bayview Circle
JHAAC, Room 1B.1A
Baltimore, Maryland 21224
Home Page: http://vasculitis.med.jhu.edu

Plasmapheresis may be of benefit in some cases of polyarteritis nodosa. This procedure is a method for removing unwanted substances (toxins, metabolic substances and plasma parts) from the blood. Blood is removed from the patient and blood cells are separated from plasma. The patient's plasma is then replaced with other human plasma and the blood is retransfused into the patient.

Jennette JC. Polyarteritis Nodosa. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:28-29.

Beers MH, Berkow R., eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:439-42.

Berkow R., ed. The Merck Manual-Home Edition.2nd ed. Whitehouse Station, NJ: Merck Research Laboratories; 2003:387-88.

REVIEW ARTICLES
Ramos-Casals M, Font J. Extrahepatic manifestations in patients with chronic hepatitis C virus infection. Curr Opin Rheumatol. 2005;17:447-55.

Langford CA. Vasculitis in the geriatric population. Clin Geriatr Med. 2005;21:631-47.

Keystone EC. The utility of tumour necrosis factor blockade in orphan diseases. Ann Rheum Dis. 2005;63 Suppl 2:ii79-ii83.

Golnik KC. Neuro-ophthalmologic manifestations of systemic disease: rheumato-logic/Inflammatory. Ophthalmol Clin North Am. 2004;17:389-96.

Ting TV, Hashkes PJ. Update on childhood vasculitides. Curr Opin Rheumatol. 2004;16:560-65.

Younger DS. Vasculitis of the nervous system. Curr Opin Neurol. 2004;17:317-36.

Uthman I. Pharmacological therapy of vasculitis: an update. Curr Opin Pharmacol. 2004;4:177-82.

Herbert CT, Russo GG. Polyarteritis nodosa and cutaneous polyarteritis nodosa. Skinmed. 2003;2:277-83.

Guillevin L, Pagnoux C. Indications of plasma exchanges for systematic vasculitides. Ther Apher Dial. 2003;7:155-60.

FROM THE INTERNET
Polyarteritis nodosa. MedlinePlus. Medical Encyclopedia. Update Date: 7/12/2004. 2pp.
www.nlm.nih.gov/medlineplus/ency/article/001438.htm

Polyarteritis Nodosa. Types of Vasculitis. The Johns Hopkins Vasculitis Center. 2004. 6pp.
http://vasculitis.med.jhu.edu/typesof/polyarteritis.html