HISTOLOGIC TRANSFORMATION OF BENIGN ENDOMETRIOSIS TO EARLY EPITHELIALOVARIAN-CANCER

Between 1975 and 1990, 79 patients with Stage I epithelial ovarian can cer were treated at Massachusetts General Hospital. Patients were iden tified from the tumor registry and medical records were retrospectivel y reviewed. Pathological slides were evaluated for the presence of end ometriosis, specifically looking for malignancy arising in endometrios is. Evidence of endometriosis was found in 22 of the 79 cases (28%). I n the 23 cases of endometrioid histology, 9 cases (39%) were associate d with endometriosis and, in the 17 cases of clear cell tumors, 7 (41% ) were associated with endometriosis. All 8 cases of mixed histology h ad clear cell and/or endometrioid components and 4 cases (50%) were as sociated with endometriosis. Endometrioid adenocarcinoma accounted for 41% of the tumors associated with endometriosis, clear cell carcinoma 31%, mixed (endometrioid and/or clear cell types) 18%, and other type s 9%. Among the 22 patients with associated endometriosis, we found 7 carcinomas (32%) arising in endometriosis. In these 7 cases a spectrum of benign and atypical endometriosis with a transition to clear cell or endometrioid adenocarcinoma were identified. These premalignant cha nges were characterized by cytologic atypia and architectural prolifer ation. Endometriosis was frequently encountered among patients with St age I epithelial ovarian cancer of endometrioid and clear cell histolo gies. Endometriosis may play a role in the pathogenesis of some early stage malignant ovarian epithelial neoplasms. (C) 1996 Academic Press, Inc.