Could prominent airway-centered fibroblast foci in lung biopsies predict underlying chronic microaspiration in idiopathic pulmonary fibrosis patients?

Abstract

Chronic occult aspiration of small droplets (microaspiration) due to gastroesophageal reflux disease (GERD) and/or hiatal hernia is postulated to be a contributing factor in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Usual interstitial pneumonia (UIP) is the histopathologic correlate of IPF. We hypothesized that chronic microaspiration may manifest as prominent airway-centered fibroblastic foci (FFs) in IPF. UIP cases diagnosed by wedge biopsies over a 6-year period (2006-2011) were identified and scored (1-3) for the prominence of airway-centered FFs by 2 authors blinded for clinical history. Relevant clinical information was obtained. Thirty-seven patients (22 men) were diagnosed with IPF by multidisciplinary approach. Thirteen cases (35.1%) demonstrated high airway-centered FF score (score 3). Twenty (54.1%) patients carried a clinical diagnosis of GERD, and 3 patients (8.1%) had hiatal hernia. High airway-centered FF score was significantly associated with hiatal hernia diagnosis (P=.037) but not with a diagnosis of GERD or the use of proton pump inhibitors/histamine-2 receptor antagonists. High airway-centered FF score was associated with airway-centered acute inflammation (P=.028) and peribronchiolar granulomas (P=.042). In summary, IPF cases with hiatal hernia were more likely to have a prominent airway-centered FF. Given the strong association between hiatal hernia and GERD and their risk for developing chronic microaspiration, the prominent airway-centered FF in UIP might predict the presence of chronic microaspiration, acknowledging that GERD and proton pump inhibitor/histamine-2 receptor antagonist use failed to demonstrate a significant association. Larger studies are warranted for further investigation.