Table 3. Recategorization of Possible UIP Pattern on High-Resolution CT: Excerpt from an Official ATS/ERS/JRS/ALAT Guideline in 2011 and 2018, and a Fleischner Society White Paper in 2018.
| Distribution | Features | |
|---|---|---|
| Typical UIP (2018) [8, 9] | Subpleural predominant and basal predominant (occasionally diffuse) | Honeycombing |
| Reticular pattern with peripheral traction bronchiectasis or bronchiolectasis | ||
| Often heterogeneous | ||
| Probable UIP (2018) [8, 9] | Subpleural and basal predominant | Reticular pattern with peripheral traction bronchiectasis or bronchiolectasis |
| Often heterogeneous | ||
| May have mild GGO | ||
| Absence of honeycombing | ||
| Absence of features to suggest an alternative diagnosis | ||
| Indeterminate for UIP (2018) [8, 9] | Subpleural and basal predominant | Subtle reticulation |
| May have mild GGO or distortion | ||
| Some inconspicuous features suggestive of non-UIP pattern | ||
| Most consistent with non-IPF diagnosis (2018) [8, 9] | Upper-lung or mid-lung predominant fibrosis | Any of the following: predominant consolidation, extensive pure ground glass opacity (without acute exacerbation), extensive mosaic attenuation with extensive sharply defined lobular air trapping on expiration, diffuse nodules or cysts |
| Peribronchovascular predominance with subpleural sparing | ||
| UIP (2011) [7] | Subpleural and basal predominant | Reticular abnormality |
| Honeycombing with or without traction bronchiectasis | ||
| Absence of features listed as inconsistent with UIP pattern | ||
| Possible UIP (2011) [7] | Subpleural and basal predominant | Reticular abnormality |
| Absence of features listed as inconsistent with UIP pattern | ||
| Inconsistent with UIP (2011) [7] (any of seven features) | Upper or mid-lung predominance | Extensive ground glass abnormality (extensive reticular abnormality) |
| Peribronchovascular predominance | Profuse micronodules (bilateral, predominantly upper lobes) | |
| Discrete cysts (multiple, bilateral, away from areas of honeycombing) | ||
| Diffuse mosaic attenuation/air-trapping (bilateral, in three or more lobes) | ||
| Consolidation in bronchopulmonary segment(s)/lobe(s) |
ALAT = Latin American Thoracic Association, ATS = American Thoracic Society, ERS = European Respiratory Society, GGO = ground-glass opacities, IPF = idiopathic interstitial fibrosis, JRS = Japan Respiratory Society, UIP = usual interstitial pneumonia