**6.2 Immunophenotypic features of ovarian clear cell carcinomas**

OCCCs are strongly immunopositive for Napsin A (80–85%) and HNF1β (80–92%) [124, 125] and negative for WT1, ER and PgR. In addition, OCCCs show a wild-type pattern of p53 expression [126]. Differential diagnosis of OCCCs should be made among ECs and HGSCs because in bothtumours clear cell change can be observed, HGSCs demonstrate positive immunoreaction for WT1 and ER while ECs show positivity for ER [127]. Additionally, both tumours (HGSCs and ECs) are negative for napsin and HNF1β [127].
