OC05.04: Ultrasound masks of not‐typical endometriomas: preoperative assessment of their malignancy risk and clinical‐surgical characteristics

Not-typical ovarian endometriomas is a category of tumours where preoperative ultrasound (US) diagnosis can be challenging and indeterminate. A retrospective, monocentric descriptive study was conducted. 3460 adnexal masses were diagnosed by US with subsequent surgical treatment and pathological examination during 8 year-period at the gynecological US reference centre. Out of 1072 ovarian endometriomas identified, 1022 were typical in presentation. However, in non-pregnant patients, 50 out of the 1072 cases (4.6%) showed not-typical sonographic features. Simultaneous presentation of US and endoscopic images is important for the diagnostic experience and professional competencies of the sonologist. The US characteristics of not-typical endometriomas in the studied series were diverse, such as giant size, papillations with or without blood flow, solid non-papillary components, multilocular cysts with more than 4 compartments, multiple irregular septa, content layering into levels, non-ground-glass echogenicity of the cyst content (low-level, hyperechoic homogeneous, diffuse suspension resembling “comets”), as well as inclusion of endometrioma within the giant peritoneal cysts. Preoperative assessment of malignancy risk according to the ORADS system was distributed as follows: ORADS 3 in 5 patients, ORADS 4 in 30, ORADS 5 in 10, ORADS 0 in 5. Clinical and surgical features of not-typical endometriomas included: rupture in 3 patients, torsion in 1, cyst abscess formation in 2, non-“chocolate” content in 5, concomitant deep infiltrative endometriosis in 34/50 patients, malignancy in 3 /50 cases. The use of the term not typical for US characteristics of endometriomas appears to be preferable compared to the term atypical, as the latter is often associated with an abnormal cytological variant in publications. Pattern recognition and US expertise of an experienced sonologist are cornerstone approaches in the preoperative diagnosis of not-typical endometriomas.