The Usefulness of a Simple Classification for Bronchoscopic Findings for Diagnosis of Peripheral Pulmonary Tumour

Normal bronchial epithelium has been described in terms of transparency and smoothness. No studies have compared bronchoscopic and pathological findings in the identification of bronchial epithelium.This study aimed to classify bronchoscopic findings for peripheral pulmonary tumour (PPT) for accurate bronchoscopic diagnosis accounting for the presences of bronchial epithelium and bronchial stenosis using an ultrathin bronchoscope.We performed endocytoscopy using narrow-band imaging (NBI) of specimens immediately after lobectomy to investigate the normal bronchial epithelium under the physiological saline injection technique (PSIT) prior to classification of PPT. A retrospective study to classify bronchoscopic findings included 46 patients diagnosed with malignancy by bronchoscopy for PPT.We recognized a "light blue line" (LBL) with NBI under PSIT, corresponding to strong reflection of short-wavelength light by cilia on the epithelial surface in an ex vivo endocytoscopic study. Bronchoscopic findings of PPT were classified morphologically into stenotic type (ST) and non-stenotic type (NonST). Tumours were also classified as exposed type (ET) and non-exposed type (NonET) based on the presence of epithelium. Most ST and NonET lesions (74%) were adenocarcinoma. Among squamous cell carcinoma, 55% were categorized as ST and ET. All NonST and NonET cases were adenocarcinoma. A significant difference in the presence of LBL was seen between ET and NonET.Our simple classification based on the appearance of stenosis and LBL in PPT may facilitate pathological diagnosis.