Benign endometrioid tumours of the ovary and the Müllerian concept of ovarian epithelial tumours

The difficulties of a consistent Müllerian interpretation of the epithelial ovarian tumours include their inconstant hormonal responsiveness, the doubtful nature of the clear cell tumour and the apparent rarity of benign endometrioid forms. The reported frequency figures for the different types of endometrioid tumour suggest that their nature is made evident by proliferation. The appearance of indolent forms is explored by a study of inactive neoplastic areas associated with endometrioid carcinomas, or with proliferating endometrioid tumours or arising in endometriosis. These jointly suggest that most such tumours are identical with inactive 'serous' adenofibromas of glandular pattern and have senile endometrium as their prototype. Increasing proliferation develops more overt endometrioid forms which, if luxuriant, may be associated with corpus carcinoma. The endometrium of pregnancy is probably the prototype of the clear cell tumour, with a corresponding range of cell types. There is tenuous evidence that tumours may respond to steroid hormones if they arise in endometriosis and a difficulty of deducing such an origin is noted. The term 'serous' may be generic and comprise several different tissue types.