Here, granulomatosis refers to chronic inflammation with scattered multinucleated giant cells. True granulomas are not characteristic of Wegener's granulomatosis. Necrosis is often present.
The wall of this small vessel is replaced by granulomatous inflammation--giant cells and chronic inflammatory cells. This destructive angiitis may involve both arteries and veins. Elastic tissue stains are useful to show the destruction of the elastic layers.
Capillaritis is the cause of the alveolar hemorrhage that may occur. Here, disintegrating PMNs damage the alveolar walls causing the alveolar hemorrhage.
