Endolymphatic Stromal Myosis Associated with Tamoxifen Use

A case of low-grade endometrial stromal sarcoma (endolymphatic stromal myosis) occurring in a patient who had received tamoxifen citrate for 3 years following surgical treatment for breast cancer is presented. Endometrial adenocarcinomas have been the most frequently reported tumor associated with tamoxifen use. More recently, uterine sarcomas have also been described in association with the use of tamoxifen. This report adds only the second case of a low-grade endometrial stromal sarcoma associated with tamoxifen use. As in the first report, the tumor demonstrated a sex-cord-like pattern of differentiation, an uncommon feature of endometrial stromal sarcomas. This suggests a possible association between tamoxifen use and the subsequent development of low-grade endometrial stromal sarcoma.