Acute exacerbation of chronic interstitial pneumonia: high-resolution computed tomography and pathologic findings

PURPOSE: To review the high-resolution computed tomography (CT) and histologic findings of acute exacerbation of chronic interstitial pneumonia and to assess the potential value of CT and histologic findings in predicting prognosis. MATERIALS AND METHODS: The study included 24 patients with clinical and histologic diagnosis of acute exacerbation of chronic interstitial pneumonia who underwent CT within 1 month before biopsy or autopsy. The final diagnosis was acute exacerbation of idiopathic pulmonary fibrosis (n=12), usual interstitial pneumonia associated with connective tissue disorders (n=5), idiopathic nonspecific interstitial pneumonia (n=4), and nonspecific interstitial pneumonia associated with connective tissue disorders (n=3). RESULTS: The main CT findings consisted of bilateral ground-glass opacities (100%) and consolidation (71%) superimposed on a reticular pattern. The ground-glass opacities and/or consolidation were diffuse in 54% of the cases, multifocal in 21%, and peripheral in 25%. The histologic patterns of acute injury consisted of diffuse alveolar damage (n=20), acute organizing pneumonia (OP) (n=3), and extensive fibroblastic foci (n=1). Eight (33%) patients survived the acute episode, including all 3 patients with OP and the patient with extensive fibroblastic foci (P=0.01). The survivors included 3 of 13 (23%) patients with diffuse parenchymal opacification, 2 of 5 (40%) patients with multifocal, and 3 of 6 (50%) patients with peripheral opacification on CT. CONCLUSIONS: The CT findings of acute exacerbation of chronic interstitial pneumonia consist of diffuse, multifocal, or peripheral parenchymal opacification superimposed on reticulation. Histologic findings of OP are superior to CT in predicting prognosis.