Diagnostic yields and safety of thoracoscopic cryobiopsies in Japan: A single-center retrospective observational study

Background: Thoracoscopy is useful for diagnosing unexplained pleural effusions. A sufficient specimen volume is often difficult to obtain using forceps biopsies (FBs) but can be obtained with pleural cryobiopsies (CBs). This study aimed to assess the utility and safety of CB during thoracoscopy in the Japanese population. Methods: Patients who underwent thoracoscopic CBs at the Japanese Red Cross Medical Center between January 2017 and August 2023 were included in the study. Data were retrospectively analyzed, including clinical data, thoracoscopic findings, specimen size, diagnostic yield, and complications. The number of collected specimens and the freezing time were left to the discretion of the attending physician. Results: Twenty-six patients underwent thoracoscopic CB. Specimens obtained by CB were larger than those obtained by FB. Primary lung cancer was the most common cause of pleural effusion, followed by malignant pleural mesothelioma. CB contributed to the diagnosis in 24 of 26 cases (92.3%) and FB contributed to the diagnosis in 11 of 18 cases (61.1%). Severe fibrosis could be diagnosed in all 3 cases by CB, but not by FB. The common complications of CB included bleeding at the biopsy site and atelectasis, but no severe complications occurred. Conclusions: The utility and safety of thoracoscopic CB for diagnosing pleural effusions in Japan were verified. The diagnostic yield, specimen size, and safety profile of CB support the diagnostic utility of this method.