Significance of bronchiolocentric fibrosis in patients with histopathological usual interstitial pneumonia

To evaluate the clinical significance of bronchiolocentric fibrosis (BCF) in patients with a histopathological pattern of usual interstitial pneumonia (UIP).

Two hundred and fifty-two patients with pathological UIP pattern were identified. Two hundred and fifteen of these patients (215 of 252) had the multidisciplinary diagnosis of idiopathic pulmonary fibrosis (IPF). Prospectively defined clinical, radiological and pathological features (including BCF) were recorded, and peripheral blood MUC5B genotype and telomere length were measured. BCF was observed in 38% (96 of 252) of all patients and 33% (72 of 215) of IPF patients; its presence was associated with a non-IPF diagnosis on multivariate analysis (odds ratio = 3.71, 95% confidence interval = 1.68-8.19). BCF was not significantly associated with environmental exposures, gastroesophageal reflux, cigarette smoking or radiological patterns. There was no significant association of BCF with MUC5B genotype or telomere length. BCF has no significant impact on survival time.

Most patients with BCF and a histopathological pattern of UIP have IPF. However, this combined fibrotic pattern is associated with a non-IPF multidisciplinary diagnosis, with approximately one-quarter of these patients being diagnosed as chronic hypersensitivity pneumonia or unclassifiable interstitial fibrosis. The presence of BCF in these patients is not significantly associated with presumed clinical risk factors for bronchiolocentric involvement, radiological findings, MUC5B genotype, telomere length or survival time.