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Polyarteritis Nodosa (PAN)

PAN is a multisystem condition characterized by necrotizing inflammation of small and medium arteries without glomerulonephritis or antineutrophil cytoplasmic antibodies (ANCAs). Patients present with symptoms related to the organs most frequently involved, which include vessels of the peripheral nerves, skin, abdomen, muscle, and kidney in that order. Involvement of other organs such as the lungs and ears/nose/throat (ENT) is unlikely and should prompt another diagnosis.

Prevalence and Manifestations of Polyarteritis Nodosa in Various Organs

ORGAN

MANIFESTATION

PREVALENCE (%)

COMMENTS

Peripheral nerves

Mononeuritis multiplex

50-70

Motor and sensory deficits

Kidney

Renal artery aneurysms and infarcts

70

Hypertension, occasionally severe

Skin

Palpable purpura, ulcers, livedo, nodules

50

Mainly over the lower extremities

Joint

Arthralgias

50

Arthritis

20

Muscle

Myalgias

50-60

Gut

Abdominal pain, liver function abnormalities

30-35

Due to mesenteric arteritis

Heart

Congestive heart failure, myocardial infarction

Low

CNS

Seizures, stroke

Low

Respiratory

Ear, nose, and throat, lungs

None

Temporal artery

Jaw claudication

Low

Testis

Pain

20

More common with hepatitis B

Eye

Retinal hemorrhage, optic ischemia

Low

The cause of PAN is unknown. An immune complex-mediated mechanism is frequently considered, but immune complex deposits or complement components are seldom found in involved vessels. Direct endothelial injury with subsequent release of cytokines and mediators of inflammation is another theory, but the triggering factor or antigen has not been found. Several conditions have been associated with PAN or PAN-like vasculitis, including the following:

• Viral infections such as hepatitis B (HBV) CMV, HTLV-1, human immunodeficiency virus (HIV), parvovirus, EBV, and hepatitis C (rare)

• Autoimmune disorders such as systemic lupus erythematosus (SLE), rheumatoid arthritis, dermatomyositis, and Cogan syndrome

• Medications such as allopurinol and sulfa drugs

• Hairy cell leukemia

• Adenosine deaminase 2 loss of function mutation: cause of autosomal recessive familial PAN

Owing to HBV vaccination, HBV-associated PAN now only accounts for <10% of cases of PAN. PAN usually occurs within 6 months of HBV acquisition. In HBV-associated PAN, the traditional treatment with corticosteroids and cyclophosphamide jeopardizes the patient’s outcome by allowing the virus to persist and cause further liver damage and ongoing antigenemia.


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Web:

Hopkins Vasculitis

Vasculitis Foundation

MedicineNet

MedlinePlus

Medscape

RareDiseases NIH

rheuma-online.de (German)