What is granulomatosis with polyangiitis?

 Granulomatosis With Polyangiitis

Previously called Wegener granulomatosis, granulomatosis with polyangiitis (GPA) is a necrotizing vasculitis charac-terized by a triad of the following:

  • Necrotizing granulomas of the upper-respiratory tract (ear, nose, sinuses, throat) or the lower-respiratory tract (lung) or both
  • Necrotizing or granulomatous vasculitis affecting small-to medium-sized vessels (e.g., capillaries, venules, arteri-oles, and arteries), most prominently the lungs and upper airways but other sites as well
  • Focal necrotizing, often crescentic, glomerulonephritis.
What is granulomatosis with polyangiitis?

 

"Limited" forms of disease can be restricted to the respi ratory tract. Conversely, when widespread the disease may affect the eyes, skin, and other organs, most notably the heart; clinically, widespread GPA resembles PAN with the additional feature of respiratory involvement.

GPA is likely initiated as a cell-mediated hypersensitivity response to inhaled infectious or envirorimental antigens. PR3-ANCAs are present in almost 95% of cases and probably drive the tissue injury. The ANCA level also is a useful marker of disease acticity, as antibody titers fall dramtically with effective immunosuppressive therapy and rise prior to disease relapse.

Morphology

Upper respiratory tract lesions range from granulomatous sinusitis to ulcerative lesions of the nose, palate, or pharynx; lung findings also vary, ranging from diffuse parenchymal infil-trates to granulomatous nodules. 

There is multifocal necrotizing granulomatous vasculitis with a surrounding fibroblastic pro-liferation. Multiple granulomata can coalesce to produce radiographically visible nodules with central cavitation.

Destruction of vessels can lead to hemorrhage and hemoptysis. Lesions can ultimately undergo progressive fibrosis and organization.

The renal lesions range from mild, focal glomerular necrosis associated with thrombosis of isolated glomerular capillary loops (focal and segmental necrotizing glomerulonephritis) to more advanced glomerular lesions with diffuse necrosis and parietal cell proliferation forming epithelial crescents (crescen-tic glomerulonephritis).

Clinical Features

  • The typical patient is a middle-aged man, although women and individuals of other ages can be affected.

  • Classic presentations include:

    • Bilateral pneumonitis with nodules and cavitary lesions (95%)

    • Chronic sinusitis (90%)

    • Mucosal ulcerations of the nasopharynx (75%)

    • Renal disease (80%)

  • Patients with mild renal involvement may demonstrate only hematuria and proteinuria, whereas more severe disease may portend rapidly progressive renal failure.

  • Rash, myalgias, articular involvement, neuritis, and fever also may occur.

  • If untreated, the mortality rate at 1 year is 80%.

  • Treatment with:

    • Steroids

    • Cyclophosphamide

    • TNF inhibitor

    • Anti-B-cell antibodies (rituximab)
      has improved this considerably.

  • Most patients with GPA now survive, but remain at high risk for relapses that may ultimately lead to renal failure.





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