Granulomatous vasculitis.

Vasculitides are classified by the size of the vessel involved and by the nature of the inflammatory process. Pulmonary granulomatous vasculitis encompasses several entities that are in general characterized by granulomatous inflammation, extensive necrosis, and a variegated cellular infiltrate. Wegener's granulomatosis is a prototype of granulomatous vasculitis and is a disease of unknown etiology that often involves the upper respiratory tract, the lower respiratory tract, and the kidneys. Some of the entities initially classified as pulmonary granulomatous vasculitis have subsequently been found to represent other entities; specifically, lymphomas (lymphomatoid granulomatosis) and part of the spectrum of bronchopulmonary aspergillosis (bronchocentric granulomatosis). In addition, it is recognized that certain infectious conditions, specifically the necrotizing inflammatory processes caused by fungi and mycobacteria, can show granulomatous vasculitis and can be confused with Wegener's granulomatosis. The mechanism by which pulmonary granulomatous vasculitis occurs is not well understood, although is thought to have an immunologic basis. A great deal of data has been accumulated concerning antineutrophil cytoplasmic autoantibodies and the role that these antibodies might play in the development of these conditions.