9-27: Pulmonary Vasculitis

Granulomatosis with polyangiitis is an idiopathic disease manifested by a combination of glomerulonephritis, necrotizing granulomatous vasculitis of the upper and lower respiratory tracts, and varying degrees of small-vessel vasculitis. Chronic sinusitis, arthralgias, fever, skin rash, and weight loss are frequent presenting symptoms. Specific pulmonary complaints occur less often. The most common sign of lung disease is nodular pulmonary infiltrates, often with cavitation, seen on chest radiography. Tracheal stenosis and endobronchial disease are sometimes seen. The diagnosis is most often based on serologic testing and biopsy of lung, sinus tissue, or kidney with demonstration of necrotizing granulomatous vasculitis (Chapter 20).

Eosinophilic granulomatosis with polyangiitis is an idiopathic multisystem vasculitis of small and medium-sized arteries that occurs in patients with asthma. The skin and lungs are most often involved, but other organs, including the paranasal sinuses, the heart, gastrointestinal tract, liver, and peripheral nerves, may also be affected. Peripheral eosinophilia greater than 1500 cells/mcL (greater than 1.5 × 10⁹/L) or greater than 10% of peripheral WBCs is the rule. Abnormalities on chest radiographs range from transient opacities to multiple nodules. This illness may be part of a spectrum that includes polyarteritis nodosa. The diagnosis requires demonstration of histologic features, including fibrinoid necrotizing epithelioid granulomas and eosinophilic granulomas.

Treatment of pulmonary vasculitis usually requires corticosteroids and cyclophosphamide. Oral prednisone (1 mg/kg ideal body weight per day initially, tapering slowly to alternate-day therapy over 3–6 months) is the corticosteroid of choice; in granulomatosis with polyangiitis, some clinicians may use cyclophosphamide alone. For fulminant vasculitis, therapy may be initiated with intravenous methylprednisolone (up to 1 g intravenously per day) for several days. Cyclophosphamide (1–2 mg/kg ideal body weight orally per day initially, with dosage adjustments to avoid neutropenia) is given until complete remission is obtained and then is slowly tapered, and often replaced with methotrexate or azathioprine for maintenance therapy.

Five-year survival rates in patients with these vasculitis syndromes have been improved by combination therapy. Complete remission can be achieved in over 90% of patients with granulomatosis with polyangiitis. The addition of trimethoprim-sulfamethoxazole (one double-strength tablet by mouth twice daily) to standard therapy may help prevent relapses.