LAUSR

Introduction: chILD comprises various rare respiratory conditions and partially overlaps with adult ILD. Lung fibrosis is the most common disease entity in adults; however, there are no data on the prevalence, clinical, radiological and histopathological presentation of pulmonary fibrosis in chILD. Aim: To assess the prevalence of fibrosis in lung biopsies from the international management platform, the European chILD registry (NCT02852928), and to correlate paediatric lung fibrosis with radiological findings. Methods: Features of fibrosis in biopsies were defined by the presence of any of the following: description of interstitial fibrosis, fibroblastic foci or honeycombing. A histological diagnosis of chronic pneumonitis of infancy (CPI) was also included. Fibrosis by chest computed tomography (CT) scans was defined by the presence of linear or reticular opacities, honeycombing, traction bronchiectasis or architectural distortion. Results: Lung biopsies were available for 149/825 chILD cases (18%); 46 biopsies (31%) had features of fibrosis and 11 were identified by CPI pattern alone. Mean age at biopsy was 6.4 years (range 0–26). Thirty cases were related to alveolar surfactant region (ABCA3: n=11; SFTPC: n=3), five to systemic disease processes (e.g. connective tissue disease: n=2) and three to immunodeficiency. Individual cases accounted for the other categories. Only 21/46 cases (46%) with biopsy-proven features of fibrosis had fibrosis features by CT. Conclusions: Features of fibrosis were already present in 31% of cases with a diagnostic lung biopsy. Concordance between biopsy- and CT-diagnosed fibrosis was lower than expected and requires further evaluation.