Furthermore, 60 % of the cells showed nuclear staining for the biomarker HNF1β, a protein considered to be pivotal in the pathogenesis of O-CCC as evolving from endometrioid lesions [8, 13], and found to have high sensitivity and specificity to differentiate O-CCC from high-grade serous ovarian cancers [7]. This evidence concerns the gene HNF1B and ovarian serous adenocarcinoma.