CA 125 in ovarian cysts, serous effusions and peritoneal washings: immunocytochemical expression

The immunocytochemical expression of CA 125 in ovarian cysts, serous effusions and peritoneal washings was examined in patients with primary ovarian malignancies (22) and benign gynecologic conditions (96). The immunostaining of CA 125 was assessed in serous ovarian cysts (CA 125 was detected in 3 out of 14 serous ovarian cysts), follicular ovarian cysts (0/5), luteinized cysts (3/3), endometriotic cysts (6/11), serous cystoadenomas (4/4) and mucinous cystoadenomas (0/2). Reactive mesothelial cells (6/6) showed a low but homogeneous staining which was never found in negative peritoneal washings (0/47). Neoplastic cells in positive peritoneal washings were highly positive (20/22), except for 2 mucinous cystoadenocarcinomas. The reactivity of OC 125 with endometrial and reactive mesothelial cells shows the importance of employing a combination of MoAbs to improve conventional morphologic diagnosis.