Polyarteritis nodosa revisited.
Polyarteritis nodosa (PAN), the prototype of systemic vasculitis, is a rare condition characterized by necrotizing inflammation of medium-sized or small arteries without glomerulonephritis or vasculitis in arterioles, capillaries, or venules. Signs and symptoms of this disease are primarily attributable to diffuse vascular inflammation and ischemia of affected organs. Virtually any organ with the exception of the lungs may be affected, with peripheral neuropathy and symptoms from osteoarticular, renal artery, and gastrointestinal tract involvement being the most frequent clinical manifestations. A clear distinction between limited versus systemic disease and idiopathic versus hepatitis B related PAN should be done because there are differences in the implicated pathogenetic mechanisms, their treatment, and prognosis. Currently, corticosteroids plus cyclophosphamide is the standard of care for idiopathic PAN, in particular for patients with adverse prognostic factors (more severe disease), in whom this combination prolonged survival. In contrast for hepatitis B related PAN treatment consists of schemes that include plasmapheresis and antiviral agents.