Necrotizing Angiitis

Necrotizing angiitis consists of segmental necrosis of small elastic arteries, muscular arteries, or veins. The inflammation may be acute with medial destruction by PMNs with or without fibrinoid necrosis, or it may be granulomatous with epithelioid cells and giant cells. With time the lumen is narrowed by myointimal cells, and scarring occurs. An elastic van Gieson stain will show the destruction of the elastic layers of the vessel.

This small vessel shows destruction of the wall by chronic inflammatory cells, epithelioid cells, and multinucleated giant cells. In this instance, the vessel is surrounded by alveoli and separate from the area of granulomatosis.

This vessel shows segmental necrosis that replaces three quarters of the wall by homogeneous, pink, fibrinoid material (arrow) and PMNs. The endothelial cells are enlarged and reactive. The quarter of the wall at the left is more normal. This vessel is embedded in an area of granulomatosis.

This elastic van Gieson stain shows focal disruption of the inner elastic layer and replacement of the wall by loose connective tissue. The outer elastic layer is mostly intact. This stain is useful for identifying damaged vessels.

Destructive angiitis, granulomatosis, and necrosis together are the histologic features that confirm the diagnosis of WG, if the clinical picture is compatible and if cultures are negative for organisms.

Clinical summary Capillaritis Discussion

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