Bronchoalveolar lavage cell differential count is associated with survival and radiological UIP pattern in familial pulmonary fibrosis

BACKGROUND: Bronchoalveolar lavage fluid (BAL) cell differential count analysis is a common diagnostic tool in interstitial lung diseases (ILD), but studies of the BAL cell profile in familial pulmonary fibrosis (FPF) are sparse. In this retrospective cohort study, we aimed to determine BAL cell profile in patients with FPF and to compare findings to those with idiopathic pulmonary fibrosis (IPF) or asbestosis. We also investigated BAL cell profile according to clinical features, radiological usual interstitial pneumonia (UIP) patterns, survival and additionally in the subgroups of the patients with pathogenic gene variants and histological investigations. METHODS: Data were collected from medical records between 1 January 2000 and 30 September 2024. The inclusion criterion was pulmonary fibrosis (PF) (ICD 10-code J84.X), with at least one self-reported relative with PF and BAL data available. High-resolution computer tomography (HRCT) scans and histology were re-evaluated. RESULTS: The BAL results of 49 FPF patients were compared with 72 IPF and 90 asbestosis cases. Differences in BAL cell profile were revealed between groups of FPF, IPF, and asbestosis. Furthermore, we found differences in BAL cell profile between smoking habits and radiological UIP patterns. The BAL results of the patients with pathogenic gene variants were variable. Moreover, BAL eosinophils associated with survival in FPF and familial IPF. CONCLUSIONS: As a novel finding, a high proportion of BAL eosinophils is associated with shortened survival of patients with FPF, thus emphasising the need to further investigate the role of eosinophils in the pathogenesis of FPF.