EP23.11: Benign and malignant ovarian stromal tumours: clinical features, preoperative ultrasound diagnosis and endoscopic correlations

Ovarian sex cord-stromal tumours (OSCSTs) – a category of ovarian tumours where preoperative ultrasound (US) diagnosis can be challenging and indeterminate. A retrospective, monocentric descriptive study. 3460 adnexal masses were diagnosed by US with subsequent surgical treatment and pathological examination during 8 year-period at the gynecological US reference centre. Within the group, 69 cases were histologically confirmed OSCSTs. The study included analysis of clinical, histological, and US characteristics, evaluation of preoperative oncological risk stratification based on IOTA-ORADS criteria, along with examination of endoscopic images. Histological variations of both benign and malignant OSCSTs included: 51 ovarian fibroma-thecoma, 1 ovarian fibrothecoma, 4 Sertoli cell tumours, 4 Leydig cell tumours, 1 malignant Sertoli-Leydig cell tumour, 8 granulosa cell tumours. 22/69 were larger masses (>10cm), 38 medium-sized masses, and 9 smaller masses (<5cm). The US structure of OSCSTs varied: hypoechoic mases with fan shaped shadowing (uterine fibroid-like masses, 22), solid hypoechoic heterogeneous masses without acoustic shadowing (10), mass with the reticular pattern (1), solid masses with small irregular cysts (“Swiss cheese” appearance, 4), solid masses with large anechoic unilocular cysts (2), unilocular cyst with small solid lateral component (1), solid lobulated mass with multiple hypoechoic lobes (1), multilocular solid cyst with irregular septa and low-level content (1). An accurate preoperative diagnosis based on tumour-specific characteristics was achieved in 30/69 patients, while 39/69 patients had an indeterminate preoperative diagnosis. OSCSTs are relatively rare, comprising 2% of ovarian neoplasms. Their US characteristics are not clearly delineated by IOTA descriptors. Malignancy risks are not accurately assessed by either ADNEX or ORADS systems. Pattern recognition and the US expertise of an experienced sonologist are fundamental in achieving a preoperative diagnosis.