Which histologic findings are characteristic of granulomatosis with polyangiitis (GPA) in the lungs?

Updated: Aug 31, 2021
  • Author: Christopher L Tracy, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Histologic examination of lung samples may reveal the classic triad of parenchymal necrosis, vasculitis, and granulomatous inflammation characterized by an inflammatory infiltrate composed of neutrophils, lymphocytes, plasma cells, histiocytes, and eosinophils. (See the images below.)

Lung biopsy specimen from a patient with granuloma Lung biopsy specimen from a patient with granulomatosis with polyangiitis showing evidence of vasculitis and inflammation (high-power view). Image courtesy of Z. Xu, MD.
Lung biopsy specimen from a patient with granuloma Lung biopsy specimen from a patient with granulomatosis with polyangiitis showing evidence of vasculitis and inflammation (high-power view). Image courtesy of Z. Xu, MD.

Pulmonary vasculitis may affect arteries, veins, and capillaries, is pauci-immune, and can be granulomatous or nongranulomatous. Vasculitis causes vessel wall necrosis with infiltration by neutrophils, which degenerate and become surrounded by palisading histiocytes and multinucleated giant cells. The neutrophilic debris coalesces into irregularly bordered microabscesses, which can become extensive areas of "geographic" necrosis.


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