Histologic features associated with hormonal responsiveness of ectopic endometrium

To correlate histologic parameters of endometriosis with hormonal responsiveness. Seven hundred sixty-eight unselected endometriotic implants and the corresponding intrauterine endometrium from 196 patients were classified by standard endometrial dating criteria. In addition, other histologic characteristics of endometriotic implants such as the amount of stroma, amount of fibrosis, the presence of surface epithelium, presence of focal hemorrhage, and gland characteristics were also noted. Academic tertiary referral center. Comparison of histologic dating between endometriotic implants and the corresponding endometrium as a function of histologic parameters. Implants that were synchronous with the corresponding eutopic endometrium had more stroma than those that were out of phase. The amount of fibrosis was inversely related to hormonal responsiveness. The presence of surface epithelium in implants was also associated with an impaired response (28.0% versus 48.0% in phase). Endometriomas were found to be in phase with the corresponding endometrium less often than other types of implants (21.7% versus 43.3%). Although endometriomas had similar amounts of stroma when compared with other implants, they had significantly more fibrosis (850.2 μm versus 195.0 μm). These results suggest that the unpredictable response of endometriotic implants to cyclic endogenous hormones and hormonal therapy may be related to the architectural relationships between the cellular elements found in normal endometrium.