Abstract
A 65-year-old woman visited our hospital complaining of dyspnea several days before admission. A chest X-ray showed massive right-sided pleural effusion, which was not observed 1 month previously. Although the patient had never been diagnosed with cirrhosis at regular visits, the patient was diagnosed with primary biliary cholangitis at admission. Hepatic hydrothorax was suspected because pleural effusion was transudative. A diaphragmatic fistula was confirmed and closed by thoracoscopy. Pleural effusion did not reappear after this procedure. Existence of a diaphragmatic defect should be confirmed under direct vision if pleural effusion accumulates acutely or becomes beyond control.