Introduction: Guidelines remain controversial regarding the need for surgical lung biopsies
(SLB) in patients with a high-resolution computed tomography (HRCT) pattern of probable usual interstitial pneumonia (UIP). The 2018 ATS/ERS/JRS/ALAT guidelines provided a conditional recommendation for SLB after multidisciplinary discussion (MDD), while the Fleischner Society stated that a confident diagnosis of idiopathic pulmonary fibrosis (IPF) could be made without SLB depending on the clinical context. Transbronchial lung cryobiopsies (TLC) are an interesting safe alternative to SLB, but their contribution in patients with probable UIP remains largely unknown.

Methods: We retrospectively reviewed all final diagnoses made in MDD after TLC in patients with a HRCT pattern of probable UIP in our tertiary center from 2015 to 2022.

Results: Among 108 patients who underwent TLC for ILD, 21 had a HRCT pattern of probable UIP. TLC were performed because MDD didn?t provide a confident diagnosis of IPF. Their median age was 70 years and 5 were women. Median (IQR) FVC and DLCO were 84% (78-92%) and 58% (50-60%) of predicted value, respectively. Six (29%) patients reported domestic exposure, 11 (52%) never smoked or cumulated less than 5 pack years. After MDD, fibrotic hypersensitivity pneumonitis (HP) was diagnosed in 33% of cases, i.e. as much as IPF diagnoses. Among the 7 patients with HP, only 2 reported domestic exposure and only 2 exhibited alveolar lymphocytosis ?30% in BAL.

Conclusion: HP is not unusual in patients with a HRCT pattern of probable UIP, even in the absence of reported exposure or alveolar lymphocytosis. This highlights the need to discuss lung biopsies in such patients, including TLC.