Timor-Tritsch IE, Foley CE, Brandon C, et al. - Via performing this retrospective study of women with a histologic diagnosis of borderline ovarian tumor (BOT) following surgical resection who had undergone preoperative transvaginal ultrasound (TVS) examination, researchers sought to describe a new sonographic microcystic pattern, which is typical of BOT papillary projections, solid component(s) and/or septa. Further, they assessed the utility of the pattern as a new ultrasound marker that is capable of distinguishing BOT from other adnexal masses, and to present/obtain histologic confirmation. In the final analysis, 62 patients (67 ovaries) were included. Sixty (89.6%) of the 67 BOTs showed a microcystic pattern in the papillary projections, solid component(s) and/or septa on TVS. These included 46 (97.9%) of the 47 serous BOTs, 11 (73.3%) of the 15 mucinous BOTs and three (60.0%) of the five seromucinous BOTs. Microscopic evaluation revealed the characteristic 1–3-mm fluid-filled cysts in 60 (89.6%) of the 67 samples similar to those seen on TVS. The novel sonographic marker of BOT, a ‘microcystic pattern’ of BOT papillary projections, solid component(s) and/or septa, could be used to identify BOT correctly, discriminating it from ovarian cancer and benign ovarian pathology, and could ensure appropriate clinical and surgical management.