Abstract
Tamoxifen, a selective estrogen receptor modulator, is widely used to treat breast cancer, but an association has been reported between tamoxifen and the development of endometrial lesions, including endometrial carcinoma, endometrial polyps, and endometrial hyperplasia. There have also recently been a few reports on the relation between tamoxifen and adenofibroma. We present two case reports, one of a patient with a uterine adenofibroma and one of a patient with an endometrial polyp, both of whom received tamoxifen. Cases 1 and 2 are 75- and 65-year-old postmenopausal women, respectively, undergoing tamoxifen therapy. In both cases, endometrial thickening and many small cysts in the uterine cavity were revealed by transvaginal ultrasonography or magnetic resonance imaging. Postoperative microscopic examination confirmed the mass as an adenofibroma in case 1 and as an endometrial polyp in case 2.