Extremely elevated CA-125 in benign ovarian disease due to stretch of the peritoneum

Serum concentrations of CA-125 are rarely elevated beyond 1000 U/ml in benign conditions of the ovary in postmenopausal women. In this report, the authors present an unusual case of a 78-year-old woman with an extremely elevated CA-125 concentration of 2897 U/ml without the presence of a malignancy, ascites or pleural effusion. Imaging revealed a large intra-abdominal cystic mass with irregular solid deviations on CT scan, most likely arising from an ovary. Exploratory laparotomy was performed with suspicion of ovarian cancer but histopathological analysis revealed benign serous cystic adenofibroma. This case report highlights the diagnostic challenge of extremely increased levels of CA-125 in postmenopausal women. A possible explanation for this CA-125 elevation could be the mechanical stretch of the peritoneum.