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Lung-nontumor

Granulomatous inflammation (non-infectious)

Wegener’s granulomatosis


Reviewers: Elliot Weisenberg, M.D. (see Reviewers page)
Revised: 24 September 2011, last major update September 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● Triad of necrotizing angiitis, aseptic necrosis of upper respiratory tract and lungs and focal glomerulonephritis

Etiology
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● Likely a T-cell mediated hypersensitivity reaction, the close relationship between c-ANCA titers suggests a pathogenic role
● c-ANCA likely directly activates neutrophils to release oxygen radicals and proteolytic enzymes damaging endothelium

Clinical features
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● May also involve temporal artery, cutaneous small vessels and cause extrapulmonary masses; rarely involves eyes, skin and heart
● All ages, but most common with ages 45+; more common in males
● Rarely associated with diffuse pulmonary hemorrhage
● Should order special stains and cultures to rule out TB and fungi
Chest Xray: waxing and waning of pulmonary infiltrates and nodules is relatively specific
Diagnosis: biopsy of affected upper airway or skin showing inflammatory change is helpful
Limited Wegener’s: confined to lungs, no glomerulonephritis (or occurs many years later), more protracted clinical course; multiple bilateral nodules, round or infarct-like, often in lower lobes; histology similar to classic type, but must have angiitis outside of granulomas and necrotic areas for diagnosis; similar treatment

Laboratory
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● c-ANCA positive in 90% with active generalized disease and 60% with limited disease
● c-ANCA positive: diffuse cytoplasmic staining directed against neutrophil serine proteinase 3; can monitor course of disease with titers, ELISA test for anti-proteinase 3 now available
● p-ANCA: perinuclear staining, directed against myeloperoxidase, is usually negative, but positive in microscopic polyarteritis, inflammatory bowel disease, crescentic glomerulonephritis; ELISA test for anti-myeloperoxidase now available
Other causes of positive c-ANCA or p-ANCA: connective tissue disorders, chronic hypersensitivity pneumonia, postinfectious bronchitis, ulcerative colitis related lung disease, primary sclerosing cholangitis and rheumatoid arthritis (Mod Pathol 2002;15:197)

Treatment
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● Cyclophosphamide, steroids and TNF-agonists

Gross description
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● Well-circumscribed lesion with necrotic appearance

Gross images
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Necrotizing lesions

Micro description
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● Liquefactive or coagulative necrosis in lungs with profuse eosinophils, multinucleated giant cells, as part of poorly formed granulomas, surrounded by pallisading histiocytes and giant cells with central necrosis
● Destructive leukocytic angiitis of arteries and veins outside of the necrotic granuloma by neutrophils, plasma cells and eosinophils
● Scanty lymphocytes and plasma cells
● Bronchial wall is rarely involved
● Fulminant subtype has predominance of exudative changes
● Fibrous scar subtype has marked collagenous stroma
● Small vessel variant involves alveolar septal capillaries instead of large arteries or veins (resembles SLE)

Micro images
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Granulomatosis with multinucleated giant cells and chronic inflammation


Granulomatous inflammation with ill-defined lesions


Destructive angiitis

Virtual slides
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Necrotizing vasculitis

Differential Diagnosis
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● Tuberculosis
● Fungi

End of Lung-nontumor > Granulomatous inflammation (non-infectious) > Wegener’s granulomatosis


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