Tissue Continues to Be the Issue: Role of Histopathology in the Context of Recent Updates in the Radiologic Classification of Interstitial Lung Diseases

Abstract

Context.— High-resolution computed tomography (HRCT) imaging has an increasingly important role in clinical decision-making in patients with interstitial lung diseases. The recent Fleischner Society white paper on the diagnostic criteria for idiopathic pulmonary fibrosis highlights the advances in our understanding of HRCT imaging in interstitial lung diseases. Objective.— To discuss the evidence and recommendations outlined in the white paper as it pertains to the radiologic diagnosis of interstitial lung disease, specifically highlighting the current limitations of HRCT in confidently predicting histopathologic findings. Data Sources.— The recent Fleischner Society white paper and other studies pertaining to the role of HRCT in predicting histopathology in interstitial lung diseases are reviewed. Conclusions.— High-resolution computed tomography is highly predictive of a usual interstitial pneumonia (UIP) pattern on histopathology when the HRCT shows a typical UIP pattern on a “confident” read by the radiologist. A probable UIP pattern is also very predictive of a UIP pattern on histopathology, and histopathologic confirmation is not needed for most patients demonstrating this pattern in the appropriate clinical setting. A UIP pattern may be seen in a substantial proportion of patients with an “indeterminate UIP” pattern on HRCT and in many patients for whom the HRCT suggests an alternative diagnosis; histopathologic confirmation should be considered in patients demonstrating these patterns whenever feasible.