OC25.07: Ovarian cancer arising in endometrioma: ultrasound findings

To describe sonographic characteristics of malignant transformation in endometriosis. Women with histological diagnosis of ovarian borderline tumor (BOT) or carcinoma arising in endometriotic cysts, according to Samson's criteria, and undergoing preoperative ultrasound (US) examination between January 2000 and February 2009, were identified from the database of US centers of the Gynaecologic Oncology Unit of the Catholic University in Rome (Italy), Ziekenhuis Oost-Limburg in Genk (Belgium) and University Hospitals Leuven in Leuven (Belgium). The preoperative US features, described using the terms and definitions published by the International Ovarian Tumor Analysis (IOTA) group, were used for the analysis. At histological examination 4 lesions were BOT and 11 were carcinomas arising in endometriotic cysts. In all cases the presence of solid tissue was documented, with unilocular-solid in 7 (47%) and multilocular-solid morphology in 8 cases (53%). Vascularization was detectable within the solid tissue in all masses, with minimal flow in 3/15 (20%), moderate flow in 6/15 (40%), and high flow in 6/15 (40%) cases. Papillary projections, with intrapapillary vascularization, were detected in 13/15 (87%) cysts. The subjective assessment of malignancy was correct in 14/15 (93%) cases and the subjective probability was “malignant/probably malignant” in 12 cases. The only false negative case corresponded to a unilocular-solid cyst with a small papillary projection (5 mm) with an US diagnosis of a benign tumor, but the US examiner had indicated that this diagnosis was completely uncertain. BOTs and carcinomas arising in endometriotic cysts are characterized by the presence of vascularised solid tissue detectable at US. US examination could be a valuable tool to recognize malignant transformation in endometriotic cysts. The assessment of diagnostic performance of preoperative US examination in large series including histologically documented benign endometriotic cysts in ongoing.