Nonspecific interstitial pneumonia with fibrosis: High-resolution CT and pathologic findings

OBJECTIVE. The purpose of our study was to describe high-resolution CT findings of nonspecific interstitial pneumonia with fibrosis and to compare findings seen on CT with pathologic findings. MATERIALS AND METHODS. High-resolution CT findings of biopsy-proven nonspecific interstitial pneumonia with fibrosis from 23 consecutive patients (one man and 22 women) were analyzed retrospectively by two chest radiologists. CT findings were compared with pathologic findings. RESULTS. The predominant high-resolution CT finding, seen in all patients, was bilateral patchy areas of ground-glass opacity with (35%) or without (65%) areas of consolidation. Irregular linear opacities (87%), thickening of bronchovascular bundles (65%), and bronchial dilatation (52%) were also frequently seen. Honeycombing was not seen in any patient. All parenchymal abnormalities showed subpleural predominance. Areas of ground-glass opacity with or without irregular linear opacity or branchial dilatation on CT corresponded pathologically to areas of interstitial thickening caused by varying degrees of interstitial inflammation and fibrosis showing temporal uniformity. Areas of consolidation, seen at five biopsy sites, represented the areas of bronchiolitis obliterans organizing pneumonia, foamy cell collections in alveolar spaces, or microscopic honeycombing with mucin stasis. CONCLUSION. On high-resolution CT, nonspecific interstitial pneumonia with fibrosis is most commonly revealed as patchy subpleural areas of ground-glass opacity mixed with irregular linear opacity or bronchial dilatation. These areas represent interstitial thickening caused by varying degrees of interstitial inflammation, fibrosis, or both.