Pathophysiology
1) necrotizing granulomatous disease of the upper and lower respiratory tract in setting of glomerulonephropathy 2) most cases have other systemic manifestations 3) strongly associated with production of cytoplasmic antineutrophilic antibodies (c-ANCA)
Signs and Symptoms
1) purulent or bloody nasal discharge 2) sinus pain 3) destruction of nasal septum with saddle-nose deformity 4) serous otitis media 5) cough 6) dyspnea 7) chest pain 8) hemoptysis 9) airway obstruction from subglottic stenosis 10) fever
Characteristic Test Findings
Radiology-1) multinodular, bilateral cavitary infiltrates grouped around vascular structures on chest radiograph 2) bronchial obstruction with atelectasis on chest radiograph Laboratory-3) positive c-ANCA 4) increased sed rate 5) increased C-reactive protein 6) leukocytosis 7) thrombocytosis 8) anemia 9) positive rheumatoid factor 10) hematuria and red cell masts
Histology/Gross Pathology
1) necrotizing granulomatous vasculitis of small arteries and veins 2) granuloma formation 3) glomerulonephritis with crescents 4) rare granulomas in kidney
Associated Conditions
1) eye-50% of cases; episcleritis, retro-orbital mass 2) skin-45% of cases; papules, purpura, ulcers, subcutaneous nodules 3) neurologic-25%of cases; cranial neuritis, mononeuritis multiplex 4) cardiac-10% of cases; pericarditis, coronary vasculitis
Biochemistry
c-ANCA antibodies are directed against proteinase-3
Inheritance/Epidemiology
1) slight male predominance 2) rare in blacks 3) mean age of onset is 55 years 4) incidence peaks in winter months with some patients reporting a viral-like prodrome
Treatment
1) long-term cyclophosphamide plus glucocorticoids early in the course 2) alternate regimens-methotrexate or azathioprine plus glucocorticoids 3) some benefit is gained by adding trimethoprim-sulfamethoxazole (may cut relapse rate by eradicating nasal Staphylococcus aureus)
Tips for USMLE
1) Wegener’s involves the nasal passagways 95% of the time; so if it does not mention nasal pathology, it is not Wegener’s 2) classic triad-upper respiratory tract disease, lower respiratory tract disease, and kidney disease
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