Bleomycin hypersensitivity pneumonitis.

Three patients developed radiologic and functional pulmonary changes after bleomycin therapy similar to ones previously associated with administration of this drug. However, biopsy specimens showed a pattern consistent with hypersensitivity pneumonitis rather than the interstitial pneumonia usually reported in bleomycin pulmonary toxicity. There was a patchy eosinophilic infiltrate surrounding small airways and distal air spaces, but no immune deposits were noted by ultrastructure or immunofluorescence using conventional techniques and a specific antibody against bleomycin. Two of the patients had peripheral eosinophilia of 12% and 16%. All three patients showed considerable improvement on chest roentgenogram after corticosteroid treatment. Our findings are consistant with the view that bleomycin hypersensitivity pneumonitis has a different pathogenesis than bleomycin interstitial pneumonitis. Its recognition as a separate entity seems warrnated because of the favorable response to steroid therapy.