A proposal for standardization of the bronchial biopsy assessment in severe asthma

Objectives: We aimed to provide a systematized template for bronchial biopsy reading as part of the assessment of severe uncontrolled asthma. Methods: 12 severe uncontrolled asthma patients were subjected to fiberoptic bronchoscopy as part of their routine evaluation where 2-3 bronchial biopsies were taken for cellular characteristics and histopathological evaluation. Biopsies were fixed in formaldehyde and stained with H&E according to usual procedure. Biopsies were scanned, assessed and scored as described in table 1. Eight pathologists evaluated independently the biopsies and agreement between them was calculated using interclass correlation (ICC) and confidence interval (CI95%) and classified as excellent, good, or fair (ICC>0.9, between 0.7 and 0.9, or < 0.7 respectively)< Results: One patient with allergic asthma (8.3%), 7 eosinophilic asthma (58.3%), and 4 allergic & eosinophilic asthma (33.3%) were evaluated. There was excellent agreement among the pathologists regarding squamous metaplasia (ICC=0.97, CI95%= 0.92–0.99). Good agreement was detected regarding goblet cells hyperplasia, mucosal glands, submucosal eosinophils and eosinophilic count/field (ICC= 0.85, 0.87, 0.85 and 0.81 respectively) with variable CI95% ranging between fair and excellent agreement (CI95%= 0.53–0.97). However, fair agreement among pathologists was seen in basement membrane thickness, epithelial denudation, smooth muscles, submucosal neutrophils and plasma cells (ICC ≤0.7). Epithelial dysplasia was absent in all the samples. Conclusions: A standardized bronchial biopsy scoring is still required for severe asthma evaluation (FIS19/01521).