PAX2 and PAX8 reliably distinguishes ovarian serous tumors from mucinous tumors.

Ovarian cancer is the leading cause of cancer-related death in gynecologic malignancies and consists of different histologic types. Histopathologic examination and accurate subtype diagnosis has become increasingly important in guiding patient management and, as such, is the most important currently available ovarian carcinoma "biomarker." In this study, we examined the expression of PAX2 and PAX8 by immunohistochemistry in 58 cases of ovarian serous tumors and 68 cases of ovarian mucinous tumors. The results demonstrated that PAX2 and PAX8 were detected in 100% (30/30) and 77% (23/30) of serous cystadenomas, 100% (16/16) and 94% (15/16) of borderline serous cystadenomas, and 100% (12/12) and 83% (10/12) of serous carcinomas, respectively. However, PAX2 and PAX8 were detected in only 0% (0/29) and 0% (0/29) of mucinous cystadenoma, 4% (1/24) and 4% (1/24) of borderline mucinous cystadenoma, and 0% (0/15) and 7% (1/15) of mucinous carcinoma, respectively. Further, there is a linear correlation between PAX2 and PAX8 (R=0.745; P<0.0001). Overall, our data indicated that PAX2 correlated with PAX8, and these 2 proteins differentially expressed in ovarian serous tumors and ovarian mucinous tumors. Thus, PAX2 and PAX8 are useful biomarker in the differential diagnosis of ovarian serous and mucinous tumors.