524 Seromucinous borderline ovarian tumors: ultrasonographic characteristics and association with endometriosis

Introduction/Background Seromucinous borderline ovarian tumors (BOT) represents a separate BOT histotype since 2014 WHO classification. However their distinctive ultrasound characteristics have not been yet described. Their association with endometriosis has highlighted as varying widely from 30 to 70% of cases. The primary aim of the study was to describe the characteristics of seromucinous BOT (SMBOTS) and compare them with those of other BOT histotypes; the secondary aim was to evaluate the association of SMBOTs with endometriosis. Methodology This is a single-center observational retrospective cohort study including women with a histological diagnosis of BOT, who had undergone preoperative ultrasound examination by an experienced ultrasound examiner. Anamnestic data, preoperative serum carbohydrate antigen 125 (CA125) and carbohydrate antigen 19–9 (CA19–9) level, preoperative ultrasonographic characteristics of ovarian masses (according to the International Ovarian Tumor Analysis group), data about surgical treatment, presence and localization of endometriosis and histological data were extracted from medical records and surgical reports. Results Among 151 patients with histological diagnosis of BOT, 5 were rare histotypes and therefore excluded from statistical evaluation. Of the 146 women included, 96 (63.6%) had serous histotype (SBOTs), 27 (17.9%) mucinous histotype (MBOTs), 23 (15.2%) seromucinous histotype (SMBOTs). SMBOTs were more commonly left monolateral masses, had more frequently a ground glass content and only one papillary projection with moderate vascularization (Color Score 3) than other histotypes. Moreover SMBOTs presented with preoperative higher values of CA 19.9 (p value < 0,001). In 26% of all BOTs analyzed endometriosis was present, in particular in 70% of patients with histological diagnosis of SMBOTs (p value < 0,001). Conclusion In comparison with other BOT histotypes, SMBOTs appeared more commonly as left monolateral masses with ground glass content and presented one papillary projection with moderate vascularization. Moreover, they showed a higher elevation of CA19.9 and were associated with endometriosis in the majority of cases. Disclosures None.