OC03.06: Origin of acoustic shadowing as a discriminatory tool in determining the nature of neoplastic adnexal masses

Acoustic shadowing is considered a predictor of benignity in adnexal masses but may also be seen in malignant ones. We aimed to investigate whether the origin of the shadow can help determine the nature of a mass. This was a retrospective multicentre study of neoplastic adnexal masses with known histopathology, which showed acoustic shadowing on preoperative sonography. Two examiners reviewed the images and video clips, and reached consensus. The study included 100 adnexal masses with 25 different histopathologic diagnoses. More than 80% of the masses with shadowing from cystic contents (e.g. dermoid) or solid tissue because of inherent structural features (e.g. fibroma) were benign. When shadowing from solid areas arose in calcific foci (e.g. immature teratoma) or along fibrovascular tissue (e.g. serous carcinoma), 80-90% were malignant. Shadows from the margins of locules, or intracystic septae imaged perpendicularly or obliquely appeared non-informative. There was one case of shadowing from calcific foci in the walls of a mucinous cystadenoma (figure 1). Acoustic shadowing in an adnexal mass can have different connotations depending on the structure causing the attenuation. Of particular importance are shadows along the fibrovascular structures in solid tissue, which may result in malignant masses being erroneously classified as ‘likely benign’. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.