Ovarian clear cell adenocarcinoma arising in association with endometriosis: a clinicopathological study of 20 cases

Abstract

Objective: The objective of the study was to determine clinicopathological features of the ovarian clear cell adenocarcinomas (OCCA) arising in association with endometriosis. Method: We retrospectively compared 20 cases of endometriosis-associated clear cell adenocarcinoma (EACCA) with 35 cases of clear cell adenocarcinoma without endometriosis (CCAWE) diagnosed at our department between 2000 and 2013, using Student’s t-test and chi-square test to analyze the data. Results: The median age in EACCA group was 50 versus 58 years in CCAWEgroup (P=0.0007), and the prevalence of postmenopausal status was significantly higher in EACCA cases (55 % vs. 17.1 %; P=0.0035). Grossly, in the EACCA group the tumours were predominantly unilocular cysts containing solitary or multiple nodules in the inner surfaces (80 % vs. 31.4 %), while CCAWE were more frequently multilocular cystic tumours (P=0.0005). The EACCA patients tended to have smaller (median size 11 vs. 13 cm) and early-stage tumours (FIGO stage I and II combined; 85 % vs. 68.6 %), although the differences were not statistically significant. In 17 patients EACCA were arising within endometriosis, with atypical endometriosis present in 6 cases, while in the remaining 3 OCCA were adjacent to endometriosis on the same ovary. Conclusion: Patients with EACCA are typically premenopausal and younger, with a tendency to have smaller in size, early-stage tumours usually presenting as unilocular cysts.