The nature and classification of ovarian neoplasms.

The classification of ovarian neoplasms on a histogenetic basis according to presentday concepts of development and structure of the ovary is considered. There are four histogenetic categories of primary ovarian tumours: neoplasms of germ cell origin, neoplasms of celomic (germinal) epithelium and its derivatives, neoplasms of specialized gonadal stroma (sex cords and mesenchyme), and neoplasms of non-specialized gonadal stromal and heterotopic elements. In patients of all ages, 70% of ovarian neoplasms were of celomic epithelial origin, 16% of germ-cell origin, 5% of specialized gonadal stromal origin, and 9% arose from the non-specialized stroma and heterotopic elements. Before 20 years of age, 59% of ovarian neoplasms were of germ cell origin and before puberty they accounted for 90% of all ovarian tumours. The different structural types of neoplasms within the four categories are described. Accurate classification of ovarian neoplasms on a histogenetic basis is stressed if proper treatment is to be given and intelligent assessment of end results is to be made.