EP22.48: Struma ovarii with foci of follicular variant of papillary thyroid carcinoma: a case report and ultrasound presentation

Struma ovarii (SO) is a highly differentiated monodermal tumour characterised by the presence of more than 50% thyroid tissue, accounting for 2-3% of ovarian teratomas. Malignant transformation and metastasis are rare(~5%). Similar to thyroid carcinomas, the most common subtypes of malignant SO (MSO) are papillary (70%) and follicular (30%) thyroid carcinoma. Although the main treatment is surgery, there are no clear guidelines about the extent of surgery, the need for total thyroidectomy and adjuvant therapies such as radioactive iodine I-131 ablation and levothyroxine therapy. We present a case of a 31-year-old patient referred to our Department because of abdominal bloating. Transvaginal ultrasound examination showed a right multilocular solid mass of 150x89x116mm, made up by 3 portions: a solid component of 82x66x80mm, with cystic areas with a low-level content, colour score 3; a unilocular component of 100x99x117mm, with low-level content and irregular internal walls, colour score 1; a unilocular portion, of 54x36x33mm, with regular walls and mixed content, colour score 1. No ascites and no suspicious abdominal lesions were found. Oncological markers were negative (CA 125 36 mUI/ml, CA 19.9 2 U/ml). A laparotomic right oophorectomy with right ovarian fossa peritonectomy, multiple peritoneal biopsies and peritoneal washing were performed. There was no evidence of extraovarian involvement. Final histology report was positive for SO with foci of papillary thyroid carcinoma, follicular variant, stage IA. In conclusion, there are no published papers on the ultrasound features of MSO, but the accuracy of the preoperative diagnosis provides the appropriate treatment plan. 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.