Early-onset cyclophosphamide-induced interstitial pneumonitis.

This article describes three cases of biopsy-proved interstitial pneumonitis secondary to cyclophosphamide therapy. The pulmonary reactions developed after one to three courses of combination chemotherapy in three patients with diffuse histiocytic lymphoma. Resolution of the pulmonary infiltrates and blood gas value abnormalities followed discontinuation of use of this drug without recurrence when chemotherapy regimens excluding cyclophosphamide were subsequently used. Prednisone was given to all patients after the diagnosis was made, but its role in the resolution of the toxic changes is uncertain. The potential for early onset of cyclophosphamide-induced interstitial pneumonitis has not been previously stressed, but should lead to vigorous investigation of pulmonary reactions occurring at any time after initiation of therapy with this drug.