Interstitial lung disease resistant to corticosteroid therapy. Report of three cases treated with azathioprine or cyclophosphamide.

Three patients with severe progressive interstitial lung disease refractory to steroid therapy were treated with immunosuppressive drugs. Biopsy material of one showed mainly fibrosis, while that of the second showed interstitial pneumonitis as well; both patients received azathioprine. Cyclophosphamide was employed in the third patient with systemic vasculitis and massive hemoptysis. All patients had reduced lung volumes and abnormal gas exchange, which continued to worsen on high doses of steroids. In patients 1 and 2, there was long-term stabilization of lung function, while pulmonary physiologic abnormalities in the patient with vasculitis reverted to normal on five months of cyclophosphamide. Although the etiology of most forms of interstitial lung disease is unknown, several reports suggest at least a partial immunologic basis. Abatement in progression of disease in this small series would suggest that a trial of immunosuppressive drugs be considered in interstitial lung disease when steroid therapy fails.