Background. Ovarian cancer arising from an endometriotic cyst in a postmenopausal woman under tamoxifen therapy is rare. Case. We herein report the case of a 67-year-old woman with a history of breast cancer, taking tamoxifen citrate 20 mg/day for 4 years, who underwent an operation for left ovarian tumor. The postoperative histological diagnosis was endometrioid adenocarcinoma in an endometriotic cyst with a gradual transition of the degree of cellular atypia noted from typical endometriotic epithelium, to atypical endometriosis, and finally to adenocarcinoma. Conclusion. Tamoxifen may cause malignant transformation of endometriosis through atypical endometriosis even in the post-menopausal state. Atypical endometriosis may act as a precancerous lesion in the process of tamoxifen-induced malignant transformation of endometriosis.
All Science Journal Classification (ASJC) codes
- Obstetrics and Gynaecology