title: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. kokugawa@med.kyushu-u.ac.jp
authors.forename: Kaoru
authors.initials: K
authors.lastname: Okugawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Hirakawa
authors.forename: Shinji
authors.initials: S
authors.lastname: Ogawa
authors.forename: Tsunehisa
authors.initials: T
authors.lastname: Kaku
authors.forename: Hitoo
authors.initials: H
authors.lastname: Nakano
mesh_terms: D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy*; D018269:Carcinoma, Endometrioid / Q000139:chemically induced / Q000209:etiology* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000473:pathology; D004715:Endometriosis / Q000150:complications / Q000473:pathology; D005260:Female; D006801:Humans; D016609:Neoplasms, Second Primary / Q000139:chemically induced / Q000209:etiology* / Q000473:pathology; D010048:Ovarian Cysts / Q000150:complications* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000139:chemically induced / Q000209:etiology* / Q000473:pathology; D013629:Tamoxifen / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen