[Changes in the endometrium after tamoxifen therapy].

Tamoxifen belongs to the group of selective estrogen modulators (SERM) which bind to both the alpha and the beta-estrogen receptors. Depending on the type of tissue, tamoxifen has either an anti-estrogenic or an estrogenic effect on the cells. In the treatment of breast cancer, the anti-estrogenic effect is used. However, at the same time there is a predominant progestin-like and only mild estrogenic effect on the endometrium. Depending on the hormonal situation of the patient, tamoxifen can cause different morphological changes in the endometrium. On ultrasound, these changes are normally diagnosed as a thickening. However, endometrial hyperplasia or endometrial carcinoma is identified histologically in only a few cases. In the majority of cases, the diagnosis is endometrial atrophy or endometrial polyp. Other findings related to tamoxifen therapy are stromal decidualisation, regressive hyperplasia, and foci of mucinous, clear cell and serous metaplasia. The main reason for the diagnosis of endometrial hyperplasia on ultrasound could be fibrosis and edema along the border between the endometrium and myometrium. Still unsolved is the question of whether endometrial carcinomas developing after tamoxifen therapy belong mostly to type I (endometrioid) or type II (serous, clear cell) carcinomas. Only in rare cases do malignant neoplasms other than carcinomas develop after tamoxifen therapy. These are adenosarcomas, carcinosarcomas and endometrial stromal sarcomas.