Taiwanese J Obstet Gynecol • March 2007 • Vol 46 • No 1 88 ■ LETTER TO THE EDITOR ■ Tamoxifen has been used to treat patients in all stages of breast cancer. However, the drawback of its estrogen- mimicking effects on endometrium raises the risk of endometrial cancer for chronic users as it has been shown to stimulate growth of some endometrial adeno- carcinoma cell lines by estrogen receptor-independent mechanisms in vitro [3]. For long-term Tamoxifen use for breast cancer patients, development of secretory endo- metrial adenocarcinoma without estrogen receptors occurs rarely. According to the keyword searches for “secretory endometrial adenocarcinoma,” “Tamoxifen,” and “breast cancer” on MEDLINE of the reports in English language between 1970s and the end of 2005, our case is the second one to describe secretory endome- trial adenocarcinoma associated with Tamoxifen use for breast cancer. A 71-year-old woman, multigravida, complained of postmenopausal vaginal bleeding for 2 to 3 months. She had undergone right mastectomy for stage II breast cancer 15 years prior to this admission. Thereafter, she had received chemotherapy and had been taking oral 10 mg Tamoxifen twice a day for 10 years. Current medical diseases include hypertension and diabetes mellitus for 10 years and 2 months, respectively. She denied any history of estrogen replacement therapy after menopause at the age of 50 years. Under vaginal echography, unusual endometrial con- tour was detected as thick as 21 mm. Her pelvic exami- nation results revealed no senile changes but a large uterus as if in 3-months’ gestation. Coupled with atypi- cal glandular cells on her Papanicolaou smear, fractional endometrial dilatation and curettage (D&C) revealed endometrial carcinoma with secretory changes. She underwent staging laparotomy including total hysterec- tomy, bilateral salpingoophorectomy, partial omentec- tomy, sampling of pelvic and paraaortic lymph nodes, and peritoneal cytology. Grossly, the uterus showed no apparent myometrial invasion or generalized thick- ness of endometrium with multiple polypoid lesions. On paraffin sections, the tumor measured 1 cm at the great- est dimension and was estimated at only 5 mm down- ward invasion into the 3-cm thick myometrium. The histological morphology revealed a well-differentiated adenocarcinoma with dominant papillary and gland- ular patterns, consisting of columnar epithelial cells and containing intracytoplasmic basal vacuoles (Figure 1), which was similar to secretory endometrium arising from atypical complex secretory hyperplasia. Using immunohistochemical stains, we found exclusively strong positive results for progesterone receptors, SECRETORY ENDOMETRIAL ADENOCARCINOMA IN A T AMOXIFEN USER WITH BREAST CANCER AFTER MENOPAUSE Chia-Jen Wu, Yi-Jen Peng 1 , Mu-Hsien Yu, Chi-Huang Chen* Department of Obstetrics and Gynecology, and 1 Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. *Correspondence to: Dr Chi-Huang Chen, Department of Obstetrics and Gynecology, Tri-Service General Hospital, National Defense Medical Center, 325, Cheng-Kung Road, Section 2, Neihu, Taipei 114, Taiwan. E-mail: baloh.tw@yahoo.com.tw Accepted: December 6, 2006 Figure 1. Secretory endometrial adenocarcinoma showing a well-differentiated papillary pattern, comprising columnar epithelial cells with intracytoplasmic basal vacuoles, similar to the secretory phase of endometrium (hematoxylin and eosin, 100×).