Histological classification of endometriosis as a predictor of response to treatment.

Objectives: To evaluate the usefulness of the histological classification of endometriosis in predicting responses to treatment.
Methods: We evaluated 412 biopsy specimens from 241 patients with pelvic endometriosis. Pain and infertility were evaluated before surgery. Disease location and stage of development were analyzed according to the 1985 American Society of Reproductive Medicine (ASRM) classification. Histological findings were classified as stromal, well-differentiated, undifferentiated, and mixed endometriosis. Clinical response to pain or infertility was evaluated.
Results: Histological findings, disease location and stage of development, and response to treatment were compared. Undifferentiated endometriosis was more frequently associated with stages III/IV than the well-differentiated and stromal histological types. Pure or mixed undifferentiated patterns were more frequently associated with rectovaginal endometriosis. When considering pain symptoms, patients presenting well-differentiated or stromal histological patterns responded better to therapeutic treatment than those who presented undifferentiated histological patterns. There were no significant differences in cases related to sterility.
Conclusions: The histological categorization of endometriosis can help predict the behavioral patterns of the disease.