Prognostic importance of hyperplasia and atypia in endometriosis.

Endometriosis occasionally exhibits cytologic atypia in the lining of endometriotic cysts or hyperplasia resembling uterine endometrial hyperplasias, but the risk of development of adenocarcinoma in these patients is unknown. A total of 105 women with endometriosis were studied: 37 with cytologic atypia (usually in the lining of endometriotic cysts), 34 with hyperplasia resembling uterine endometrial hyperplasia, and 34 controls. For lesions resembling eutopic endometrial hyperplasia, the Kurman-Norris criteria for separating atypical hyperplasia from well-differentiated endometrial adenocarcinoma were used to subdivide this group into 23 complex atypical hyperplasias and 11 "early carcinomas." Some 62 women were successfully followed for a mean of 8.7 years. One patient with early carcinoma developed a poorly differentiated endometrioid adenocarcinoma at the vaginal apex 8.1 years later. A second patient with early carcinoma developed a mullerian mucinous tumor of low malignant potential in the contralateral ovary 7 years later. Both of the latter two patients had multifocal endometriosis. Except for persistent benign endometriotic lesions in four patients, and breast carcinoma in one, all remaining patients were alive and well at last contact. It is concluded that the Kurman-Norris criteria for eutopic endometrial adenocarcinoma may be useful in identifying rare patients with endometriosis in whom there may be an increased risk of neoplastic transformation of their endometriosis.