Interstitial Lung Disease Diagnosis

Histopathological Features of UIP and TBLC in Diagnosis of ILD

• UIP diagnosis based on patchy dense fibrosis with architectural distortion, subpleural and paraseptal lung parenchyma predilection, fibroblast foci, and absence of features suggesting alternative diagnosis
• "Probable UIP" refers to biopsies with some UIP findings in absence of features suggesting alternative diagnosis
• Traction bronchiectasis/bronchiolectasis on CT indicates probable usual interstitial pneumonia pattern
• TBLC makes applying UIP histopathological criteria challenging due to subpleural changes and potential sampling error
• TBLC more likely to show probable UIP pattern than definite UIP pattern compared to SLB
• Combination of patchy fibrosis, fibroblast foci, and absence of features usually sufficient for probable UIP pattern on TBLC
• MDD results in comparable diagnostic agreement rates for SLB and TBLC in IPF patients
• TBLC considered acceptable alternative to SLB for making histopathological diagnosis in ILD patients in experienced medical centers
• 2018 guidelines for diagnosis of IPF addressed TBLC in ILD patients, but failed to make consensus recommendation for or against TBLC
• Honeycombing on CT is essential criterion for typical UIP-IPF pattern when seen with basal and peripheral predominance
• SLB recommendation was not reevaluated in 2018 IPF diagnosis guidelines
• Systematic review identified 40 studies evaluating TBLC in ILD patients, with diagnostic yield as critical outcome and varied study characteristics including sample size and procedure used