Introduction: Pseudo-Meigs' syndrome is a syndrome that includes hydrothorax and/or ascites secondary to ovarian neoplasms other than benign primary tumors. Gastrointestinal malignancies, including colorectal or gastric adenocarcinoma, are rare etiologies for this syndrome.
Case report: In this report, we present the case of a 49-year-old woman with metastatic colon cancer who acutely developed a massive pleural effusion and ascites coincident with a rapidly enlarging adnexal mass and a rising CA-125 level.
Discussion: Seven cases of pseudo-Meigs' syndrome secondary to gastrointestinal primaries have been reported to date. This case highlights the difficulty in discerning the diagnosis of pseudo-Meigs' syndrome from that of disseminated colorectal cancer or a new primary ovarian neoplasm and the importance in making the distinction to initiate appropriate therapy.