Napsin A and WT 1 are useful immunohistochemical markers for differentiating clear cell carcinoma ovary from high-grade serous carcinoma.

Clear cell carcinoma (CCC) of the ovary is an uncommon, but an aggressive epithelial ovarian cancer (EOC), which has overlapping histopathologic features with other ovarian tumours. Lately, Napsin A has been identified as its useful diagnostic immunohistochemical (IHC) marker. Fifty-eight prospectively diagnosed ovarian CCCs, 53 high-grade serous carcinomas (HGSCs), 16 endometrioid adenocarcinomas (EMACs), six mixed carcinomas, containing components of CCC and EMAC, seven metastatic mucinous adenocarcinomas and six ovarian yolk sac tumours (YSTs) were tested for Napsin A immunostaining.