Fig. 1

CT and Histopathology UIP. a Thin slice CT at the level of the right inferior pulmonary vein in a case where 2 radiologist readers independently identified honeycombing and one reader did not identify honeycombing. After discussion, the consensus interpretation amongst the radiologist readers was that honeycombing was present and the case was classified as definite UIP. The image shows all features required for categorization of UIP by the 2018 ATS and Fleischner guidelines, including basal and subpleural predominant reticulations with peripheral traction bronchiectasis and honeycombing (ovals), and an absence of features to suggest an alternative diagnosis. b Corresponding histopathology from a subsequent surgical lung biopsy shows all features required for categorization of UIP by both guidelines, including dense fibrosis with architectural remodeling in a patchy, subpleural distribution, with honeycombing and fibroblastic foci (inset). Hematoxylin and eosin (H&E) stain. Scalebar, panel B: 0.5 mm. Scalebar, inset: 0.1 mm