Currently, PAX8 is the most commonly used immunomarker for gynecologic carcinomas; however, it lacks specificity. By mining The Cancer Genome Atlas mRNA expression profile data, Drs. Ding and Liu’s team identified SOX17 as a potential specific marker for gynecologic tumors. The authors performed immunohistochemical staining on tissue microarrays from 416 ovarian and endometrial cancer cases and 1544 solid tumors from other organs. Like PAX8, SOX17 was highly expressed in most subtypes of ovarian carcinoma (97.5% vs 97% for PAX8 in serous carcinoma, 90% vs 90% in endometrioid carcinoma, and 100% vs 100% in clear cell carcinoma), except for mucinous carcinoma (0% vs 27%). SOX17 was also highly expressed in endometrial carcinoma subtypes (88% vs 84% in endometrioid carcinoma, 100% vs 100% in serous and clear cell carcinoma). Importantly, SOX17 was not expressed in thyroid carcinomas, renal cell carcinomas, and mesotheliomas.