Immunohistochemical analysis of estrogen and progesterone receptors in endometriosis: comparison with normal endometrium during the menstrual cycle and the effect of medical therapy.

Estrogen receptors (ER) and progesterone receptors (PgR) in 19 endometriotic implants from 16 normally cycling and hormonally treated women were measured using immunohistochemical techniques and compared with 34 samples of normal intrauterine endometrium. Endometriotic implants contained specific ER and PgR in both glandular epithelium and stroma. In contrast to intrauterine endometrium, receptor content among implants was noted to be more heterogeneous, and did not undergo predictable changes in response to endogenous hormones. In the endometriotic implants of patients treated with hormonal therapy, there were significant decreases in ER and PgR in both the glands and stroma relative to untreated patients. These data imply that endometriosis is unpredictable in its response to the cyclic hormonal milieu in terms of ER and PgR, but retains the ability to respond to hormonal suppression over a prolonged interval.