A Case Suggestive of Intrathoracic Rupture of a Nonparasitic Hepatic Cyst in Polycystic Liver Disease: A Case Report.

Introduction: Rupture of nonparasitic hepatic cysts is rare and usually occurs into the peritoneal cavity, whereas intrathoracic rupture has only rarely been described. Case Presentation: We report the case of a 61-year-old woman with polycystic liver disease (PCLD) who presented with right-sided chest pain and dyspnea, suggesting intrathoracic rupture of a hepatic cyst. Computed tomography revealed unilateral pleural effusion and reduction with deformation of a large subdiaphragmatic hepatic cyst compared with prior imaging. Thoracentesis revealed transudative pleural fluid without evidence of infection or malignancy but markedly elevated levels of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9). Based on these findings, intrathoracic rupture of a nonparasitic hepatic cyst was considered the most likely etiology. The patient subsequently underwent surgical deroofing because of cyst enlargement and symptoms; however, no definitive rupture site was identified intraoperatively, and the diagnosis therefore remained presumptive. To our knowledge, this represents a very rare presentation of intrathoracic rupture of a nonparasitic hepatic cyst in PCLD. Conclusion: This case highlights the importance of comparison with prior imaging and suggests that measurement of pleural CEA and CA19-9 levels may provide limited adjunctive information when intrathoracic rupture of a hepatic cyst is suspected, although these markers are nonspecific.