Vasculitis.

Vasculitic syndromes involving the lung present a unique challenge for pathologists because of the histologic overlap with other disorders and the clinical implications of the diagnosis in regard to clinical management. This article reviews the more common vasculitic syndromes involving the lung, concentrating primarily on Wegener granulomatosis, Churg-Strauss syndrome, necrotizing sarcoid, microscopic polyangiitis, and diffuse alveolar hemorrhage syndromes. The article focuses on a review of the recent literature, diagnostic approach, and differential diagnosis.