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.

Web:

Vasculitis Foundation

rheuma-online.de (German)