Fig. 2

CT Probable UIP with Corresponding Histopathology UIP. a Thin slice CT shows basal and subpleural predominant reticulations with peripheral traction bronchiectasis (ovals) and an absence of features to suggest an alternative diagnosis, but lacks honeycombing, consistent with Probable UIP categorization by the 2018 ATS and Fleischner guidelines. The associated ground glass was interpreted as representing fine fibrosis. 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 (right inset). Spatial heterogeneity was also present (inset, left). Hematoxylin and eosin (H&E) stain. Scalebar, panel B: 0.5 mm. Scalebar, left inset: 0.4 mm. Scalebar, right inset: 0.1 mm