Usefulness of endocytoscopy in evaluating transbronchial biopsy specimens

BACKGROUND: Endocytoscopy (ECS) provides a magnification of approximately 450× for real‐time observation of lesion nuclei. Using ECS, we aimed to evaluate whether sufficient samples for diagnosis can be obtained during bronchoscopy. We also investigated whether ECS can enable two‐class diagnosis of malignant or non‐malignant transbronchial biopsy specimens in real‐time during bronchoscopy. METHODS: This was a single‐facility, prospective, observational, ex vivo study. Forty cases with localized peripheral pulmonary lesions underwent transbronchial biopsy with endobronchial ultrasonography using a guide sheath. Each biopsy specimen was immediately observed and evaluated endocytoscopically after the collection by the bronchoscopic procedure. RESULTS: Thirty‐seven cases were enrolled. The diagnostic accuracy achieved by ECS was 91.9% (34/37). The agreement rate between the endocytoscopic evaluation and pathological diagnosis of each specimen (170 specimens) was 65.3% (111/170). The median time required for endocytoscopic evaluation per specimen was 70 s. When we judged a specimen to be malignant a second time on ECS evaluations of five specimens in one case, pathologically malignant specimens were collected in 26 of 27 cases (96.3%). CONCLUSIONS: ECS with methylene blue staining may aid in the two‐class diagnosis of malignant or non‐malignant transbronchial biopsy specimens during bronchoscopy. This may reduce the number of tissue biopsies.