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

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.