Endometrial mixed Müllerian tumor with heterologous elements following tamoxifen therapy for breast cancer: a case report and literature review.

CASE: A 67-year-old multiparous woman received 20mg tamoxifen daily for four years after surgical treatment of breast cancer. She presented with vaginal bleeding. Uterine curettage revealed a uterine MMT with heterologous elements. She was treated surgically with adjuvant radiotherapy. Tumor cells were found to be estrogen receptor negative and progesterone receptor positive. Uterine MMT may be linked to long term use of tamoxifen. A mechanism in developing MMT other than estrogen receptor pathway may be possible.