Primary Epithelial Ovarian Neoplasms: New Concepts Concerning Origin, Pathogenesis and Classification Based on Morphology, Immunomarkers, Molecular Features, and Gene Expression Studies

The World Health Organization (WHO) classification of ovarian tumors, which first appeared in 1983 and since then has undergone a number of revisions, is based on morphologic features as well as on the concept that each category of ovarian tumors develops from a specific ovarian cell. According to this histogenetic classification, all the epithelial ovarian neoplasms are derived from the ovarian surface epithelium and/or from ovarian inclusion cysts, which are lined by the above epithelial cells. In recent years, a new approach to morphologic data, increasing presumptive evidence that the cell of origin of most, if not all, ovarian epithelial tumors may be extraovarian, especially from fall…