When Meigs syndrome was originally described in 1937, it was characterized by ovarian fibroma, ascites, and hydrothorax; CA-125 testing did not exist. Some of the patients with Meigs syndrome have elevated serum and/or ascitic CA-125. Subsequently, the syndrome was defined as a benign ovarian tumor (such as Brenner tumors, fibromas, fibrothecomas, granulosa cell tumors, sclerosing stromal tumors, and thecomas), ascites, and pleural effusion; following removal of the tumor, the ascites and pleural effusion swiftly resolve. This evidence concerns the gene MUC16 and Pleural effusion.