endometrioid ovarian tumours
Last reviewed 01/2018
Exceptionally, carcinoma arises in endometriosis of the ovary.
More usually, tumours arise from the surface epithelium of the ovary whose histologic pattern closely resembles that of adenocarcinoma of the uterine endometrium.
Benign endometrioid tumours are rare and usually, a unilateral cystadenofibroma.
Malignant endometrioid adenocarcinoma is the second most common form of ovarian epithelial malignancy, accounting for 20-25% of all malignant ovarian neoplasms. Peak incidence is between 50 - 60 years of age. In early stage disease, they are bilateral in about 10% of cases.
Approximately 30% of endometrioid ovarian tumours coexist with a primary endometrial cancer. The tumours probably arise synchronously, rather than as metastases from other organs. About 10% of endometrioid ovarian tumours are associated with endometriosis.
Prognosis is better than for serous or mucinous ovarian tumours, possibly because many endometrioid tumors are well differentiated.