SYSTEMIC NECROTIZING VASCULITIS

Systemic necrotizing vasculitis may be idiopathic or associated with a variety of diseases of known etiology. A typical example is polyarter itis nodosa, which is characterized by fibrinoid necrosis and severe i nflammation leading to destruction of the wall, narrowing of the lumen , and interference with blood circulation. In addition to the idiopath ic form, histologically similar lesions are seen in hepatitis B, rheum atoid arthritis, Kawasaki mucocutaneous lymph node syndrome, and other diseases. Microscopic polyangitis involves mainly small vessels-venul es more often than arterioles-but occasionally also small arteries. It s characteristic feature is leukocytoclasia of neutrophilic leukocytes , but fibrinoid necrosis also occurs. Churg-Strauss syndrome consists of granulomas in patients with a background of severe allergy such as asthma, allergic rhinitis, or occasionally drug sensitization.