Immunohistochemical expression of CDX2 in primary ovarian mucinous tumors and metastatic mucinous carcinomas involving the ovary: comparison with CK20 and correlation with coordinate expression of CK7

Recent studies have demonstrated conflicting results regarding the value of CDX2 for distinguishing primary ovarian mucinous tumors from metastatic mucinous carcinomas in the ovary. Utility of coordinate expression of cytokeratins 7 and 20 is restricted to distinction of ovarian mucinous tumors from lower gastrointestinal tract metastases and data comparing coordinate expression of all three markers is limited. Immunohistochemical studies were performed to compare expression of CDX2 and cytokeratin 20, both markers of intestinal differentiation, in conjunction with coordinate expression of cytokeratin 7, in 90 mucinous tumors involving the ovary: 42 primary ovarian mucinous tumors (31 atypical proliferative (borderline) mucinous tumors (gastrointestinal type), 11 mucinous carcinomas) and 48 metastatic mucinous carcinomas of upper (pancreaticobiliary tract: 14; stomach: five) and lower (colon and rectum: 25; appendix: four) gastrointestinal tract origin. Primary ovarian tumors expressed CDX2 (40%) less frequently than cytokeratin 20 (83%) (P