Torsion of a functional ovarian cyst in a premenopausal patient receiving tamoxifen

We report a case of torsion of an ovarian follicular cyst that developed du ring treatment with tamoxifen for breast cancer. A 40-year-old Japanese wom an was admitted complaining of acute lower abdominal pain. Eight months ear lier, she had undergone a partial mastectomy and local irradiation for duct al carcinoma of her left. breast, estrogen receptor-positive stage I (T-1a N-1b M-0). The administration of tamoxifen, 20 mg/day, and doxifluridine, 6 00 mg/day, were started immediately postoperatively, Pelvic examination aft er admission revealed the left ovarian cyst and enlarged uterus, Transvagin al ultrasonography and computed tomography revealed a multilocular cystic m ass in the pelvic cavity, The pathological diagnosis of the tumor after tot al hysterectomy and bilateral salpingo-oophorectomy was a typical follicula r cyst with torsion and uterine leiomyoma, This ovarian cyst was believed t o have developed during tamoxifen administration.