EP23.27: Female adnexal tumour of probable Wolffian origin: ultrasonographic imaging characteristics

The Female adnexal tumour of probable Wolffian origin (FATWO) originates from mesonephric remnants. Although mostly benign, its malignant potential has been reported. It's a rare finding, with approximately 100 cases reported to date. This tumour represents a diagnostic challenge due to its morphology, ultrasonographic characteristics, immunohistochemistry, and lack of specific tumour markers, often leading to confusion with epithelial and sex cord tumours. Transvaginal ultrasound imaging characteristics are limited, typically showing solid tumours with well-defined borders, cystic areas, acoustic shadowing, variable blood flow, mixed echogenicity with echogenic areas, predominantly on the right side, dependent on the broad ligament, and less frequently on the ovary. We present the case of a 48-year-old G2P2 patient who, during a follow-up transvaginal pelvic ultrasound for history of neuroendocrine tumour, showed a mass completely replacing the right ovary measuring 46x35x32mm, regular borders, vascular score of 4, predominantly solid, with a peripheral multilocular cystic area containing anechoic content, with echogenic areas causing posterior acoustic shadowing. CA 125 was reported at 11 U/mL. IOTA ADNEX showed a malignancy risk of 6.3%, Borderline 1.4%, metastatic 1%, and O-RADS 3 was calculated. The patient underwent laparoscopic bilateral salpingectomy and right oophorectomy. Pathology confirmed a FATWO. We emphasise the importance of reporting ultrasonographic characteristics for the diagnosis of such rare adnexal lesions. In our case, depicting a unilateral tumour in the right ovary, predominantly solid with well-defined borders and cystic component, mixed echogenicity with echogenic areas causing posterior acoustic shadowing, and vascularization with a score of 4, these findings are consistent with the limited previous reports in the literature.