Annals of diagnostic pathology
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Bronchiolitis combined with interstitial pneumonitis generally has been equated with bronchiolitis obliterans organizing pneumonia (BOOP). We describe our experience with lung biopsies that had both bronchiolar and interstitial diseases. We studied 31 patients who had respiratory difficulty leading to open lung biopsy, which showed a combination of both prominent bronchiolitis and prominent interstitial pneumonitis. ⋯ The natural history of these cases, which we have designated bronchiolitis interstitial pneumonitis, seems more sanguine than usual interstitial pneumonitis and worse than BOOP at least in the short term. On the one hand, response to corticosteroids was not as frequent as generally accepted for BOOP. On the other hand, disease did not progress in most patients on corticosteroids.