BackgroundBronchoalveolar lavage (BAL) cellular analysis is often recommended during the initial diagnostic evaluation of fibrotic ILD. Despite recommendation for its use, between-center heterogeneity exists and supportive data concerning the clinical utility and correlation of BAL findings with radiologic features or patterns remains sparse. Research QuestionIn patients with fibrotic ILD, are BAL findings associated with radiologic features, patterns, and clinical diagnoses? MethodsPatients with fibrotic ILD who underwent BAL for diagnostic evaluation and enrolled in the prospective Canadian Registry for Pulmonary Fibrosis were re-reviewed in a standardized multidisciplinary discussion (MDD). BAL was categorized according to guideline-recommended thresholds, and also using thresholds of lymphocytosis>20% and neutrophils>4.5%. High-resolution computed tomography (HRCT) scans were scored (blinded to clinical data) for specific features and percentage lung involvement. Radiologists classified HRCTs according to guideline-defined patterns for idiopathic pulmonary fibrosis (IPF) and fibrotic hypersensitivity pneumonitis (fHP), then MDD diagnoses were assigned, considering all available data. ResultsBronchoscopy with cellular analysis was performed in 209/1593 (13%) patients. Lymphocyte% was weakly negatively correlated with total fibrosis% (r=-0.16, p=0.023) but not statistically significantly correlated with ground glass opacity% (r=0.01, p=0.94). A mixed BAL pattern was the most frequent in all radiologic patterns (range 45% to 69%), with a minority classifiable according to BAL guidelines. BAL lymphocytosis appeared with similar frequency across HRCT patterns of fHP (21%) and UIP (18%). Only 5% of patients with MDD-based fHP had a guideline defined isolated lymphocytosis >15%. InterpretationBAL cellular analyses did not significantly correlate with radiologic features, guideline patterns, or MDD-based diagnoses. Ground glass opacities are often interpreted to represent pulmonary inflammation, but were not associated with BAL lymphocytosis in this cohort.