Although some studies reported significant differences in staining frequencies by histology, for example in serous tumors compared to clear cell histology [21], serous and endometrioid compared to other histotypes [27], mucinous and serous tumors compared to cystadenomas [9], or in tumors compared to borderline malignancies [28], most found no significant differences in EGFR staining among histotypes [15, 17, 23, 32, 44], as in the present study. This evidence concerns the gene EGFR and cystadenoma.