Ovarian endometrioid adenocarcinoma arising from an endometriotic cyst in a postmenopausal woman under tamoxifen therapy for breast cancer: a case report

Abstract

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 postmenopausal state. Atypical endometriosis may act as a precancerous lesion in the process of tamoxifen-induced malignant transformation of endometriosis.