EP23.48: Rhabdoid tumour of the ovary: clinical and ultrasound characteristics of five cases of small cell carcinoma hypercalcemic type

To describe clinical and ultrasonographic characteristics of Small Cell Carcinoma of the Ovary hypercalcemic type (SCCOHT) also known as the malignant rhabdoid tumour of the ovary. This was a retrospective study involving four ultrasound centres (Forlì, Leuven, Pamplona and Rome). Five patients (1 from International Ovarian Tumour Analysis [IOTA] database, and 4 from the databases of the departments of gynecological oncology) who underwent preoperative ultrasound examination by an experienced ultrasound examiner between 2020 and 2023 were identified with a histologically confirmed SCCOHT. The ultrasound images of all tumours were assessed using IOTA terminology. Clinical and ultrasound characteristics were reported. Median age was 29 years old (range 19-37). All patients but one were nulliparous. 4/5 patients presented with abdominal pain, 1/5 with amenorrhea. CA-125 was elevated in 3 patients (maximum value 152 U/mL). 4/5 lesions were unilateral. The median largest diameter of the lesion was 108 (range,57-195) mm. 5/5 tumours were completely solid, with inhomogeneous echostructure and no shadows. The revision of the ultrasound images revealed the presence of a “sarcoma like” echostructure, and the presence of a cystic irregular area in 3/5 patients. Preoperative calcium levels were not available. Genetic analysis for SMARCA4 (other abbreviation than above?) was obtained in 2 patients and resulted positive in both cases. This is the first study describing the ultrasonographic appearance of SCCOHT, a rare malignancy affecting young women with poor prognosis. In this case series the tumour appeared as solid with a median diameter of 108 mm. A sarcoma like echostructure with no shadows was observed in the ultrasonographic images. 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.