HNF1B and breast cancer: The positive expression of PAX8 indicates that tumors are derived from the Mullerian Duct epithelial tissue, which includes high-grade serous carcinoma, endometrial-like cancer, and CCC.[8] In terms of histology, peritoneal serous carcinoma should be first considered, especially in patients with a history of personal breast cancer.[9] HNF-1β has a high specific specificity for the diagnosis of ovarian CCC.[2] The joint applications of immunohistochemical markers WT-1, Napsina, and HNF1-β have high specificity in distinguishing high-grade serous carcinoma and CCC.