An ultrastructural study of the pathogenesis of tissue injury in limited Wegener's granulomatosis.

Intravascular lysis of leucocytes was an early event in the process of tissue injury in a patient with limited Wegener's granulomatosis. This lysis, with consequent liberation of free organelles into the circulation, was followed by platelet aggregation and fibrin deposition in vessels with intact endothelial cells. Necrosis of endothelial cells also occurred early in the tissue injury. Complete obstruction of vessel lumina, with necrosis of their walls and of alveolar pneumocytes, followed. The alveolar spaces filled with fibrin and cell debris, and macrophages and fibroblasts migrated into these areas. The ultrastructural findings offer a rationale for current therapy. Cyclophosphamide therapy led to improvement in the clinical state, pulmonary function and histological changes.