A rapidly progressive case of interstitial pneumonia.

We treated a 51-year-old woman who had rapidly progressive respiratory distress with an interstitial shadow on chest roentgenogram. Pathologically, open lung biopsy specimens showed an acutely changed lesion such as interstitial inflammatory thickening, polypoid intraluminal organizing exudates, and also honeycombing which was not recognized on chest computed tomogram. These findings were considered unconformable to acute interstitial pneumonia (AIP), bronchiolitis obliterans organizing pneumonia (BOOP), and also usual interstitial pneumonia, although the clinical diagnosis was AIP or BOOP. We diagnosed a rapidly progressive interstitial pneumonia showing an acute lung injury pattern like AIP and BOOP. She showed significant recovery with corticosteroid and cyclophosphamide.