MOC-31 is a cell surface protein with carcinogenic characteristics, expressed in healthy epithelial cells and corresponding malignant tumors, often positive in breast cancer, gastrointestinal tumors, and ovarian mucinous carcinoma, not a specific marker of clear cell ovarian tumors, and can also be positively expressed in 5% of PMM (3). Here, EPCAM is linked to ovarian clear cell tumor.