The ability of specific histopathological features to predict mortality or lung transplant in chronic hypersensitivity pneumonitis patients is unknown.
Patients with chronic hypersensitivity pneumonitis diagnosed by surgical lung biopsy were identified from an ongoing longitudinal cohort. The surgical lung biopsy slides were evaluated prospectively by an experienced thoracic pathologist using a standardized checklist to differentiate the major pathologic patterns and score the presence of specific histopathological features. Cox proportional hazard analysis was used to identify independent predictors of transplant-free survival, and Kaplan-Meier analysis was used to visualize outcomes.
119 patients were identified. Patients with fibrotic non-specific interstitial pneumonia (f-NSIP) pattern, bronchiolocentric fibrosis (BF) pattern or usual interstitial pneumonia (UIP) pattern had significantly worse transplant-free survival than those with cellular NSIP (c-NSIP) pattern or peribronchiolar inflammation with poorly formed granulomas (PI-PFG) pattern. No survival difference among patients with f-NSIP pattern, BF pattern or UIP pattern was found. Fibroblastic foci were identified in a subset of biopsies from all pathological patterns. Peribronchiolar fibrosis was noted in all UIP cases. Independent predictors of time to death or transplant included the presence of fibroblast foci or dense collagen fibrosis.
Histopathologic patterns of c-NSIP and PI-PFG had a better transplant-free survival than UIP, f-NSIP and BF patterns. Presence of fibroblast foci or dense collagen fibrosis correlated with progression to death or lung transplantation. Identification of fibroblast foci on biopsies, regardless of the underlying histopathologic pattern, may be a clinically useful predictor of survival in HP patients.