Fig. 3

CT Probable UIP with corresponding histopathology categorized as Alternative Diagnosis. a Thin slice CT shows subpleural predominant reticulations without honeycombing. Two radiologist readers classified the case as Indeterminate for UIP due to absence of conspicuous traction bronchiectasis, variable distribution and an absence of features to suggest an alternative diagnosis. One radiologist reader identified traction bronchiectasis (oval). After discussion, the consensus interpretation amongst the radiologist readers was that traction bronchiectasis was present and the case was classified as Probable UIP. b–c Corresponding histopathology from the subsequent surgical lung biopsy reveals airway-centered fibrosis with patchy organizing pneumonia and peribronchiolar granulomatous inflammation (arrows), consistent with alternative diagnosis by both guidelines. The pathologic differential diagnosis included chronic hypersensitivity pneumonitis (favored) or connective-tissue related ILD. Masson’s trichrome stain. Scalebar, panel B: 0.5 mm. Scalebar, panel C: 0.1 mm