Polyarteritis nodosa

Abstract

Polyarteritis nodosa is an exemplary multi-systemic medium-sized, primary systemic vasculitis of adults and children. Once the most frequent vasculitis, it has become progressively less common notably in developed countries due to eradication of hepatitis B virus infection, one of its most frequent causes. The evolution of clinical manifestations commences with the acute phase of neutrophilic and variable lymphocytic and eosinophilic inflammation of arterial vessel walls with medial necrosis, followed aneurysm formation, and later healing of lesions that entrains fibrotic endarteritis and vascular occlusions. The coexistence of necrotizing vasculitis, healed lesions and normal arteries in different tissues or portions of the same tissue is a pathognomonic feature of the disease. Effective treatment of polyarteritis nodosa, which includes consideration of corticosteroids and cyclophosphamide depending upon the presence of favorable or unfavorable prognostic factors, and an antiviral agent if complicated by hepatitis B infection, have improved the 5-year survival of patients. This chapter considers aspects of the classification criteria, epidemiology, main clinicopathologic features, etiopathogenesis, treatment and outcome of PAN.