The long-term outcomes of radioactive iodine therapy in malignant struma ovarii with extensive abdominopelvic metastases: a case report and literature review.

BACKGROUND: Struma ovarii (SO) is a rare type of teratoma characterized predominantly by thyroid tissue, accounting for only 1% of all ovarian tumors and 2% of ovarian teratomas. Clinical presentation commonly includes abdominal pain or irregular menstrual cycles. While typically benign, SO may rarely undergo malignant transformation, occurring in an estimated 0.3% to 5.0% of cases. Most cases of malignant struma ovarii (MSO) are diagnosed postoperatively through histopathological examination or incidentally detected during abdominal ultrasound or computed tomography scans. Although MSO exhibits biological behavior analogous to thyroid carcinomas, considerable controversy persists regarding optimal surgical extent and postoperative management, reflecting its unpredictable clinical course, metastatic potential, and relatively high recurrence rate. CASE PRESENTATION: We report the case of a 40-year-old female patient with MSO accompanied by extensive abdominopelvic metastasis. The patient underwent multiple surgeries, including tumor cytoreduction and total thyroidectomy, followed by radioactive iodine therapy (RAI). At five years of follow-up, she remained disease-free. This case is supplemented by a review of relevant literature on the diagnosis, management, and prognosis of MSO, with the aim of informing clinical decision-making for this rare condition. CONCLUSIONS: MSO presents with nonspecific symptoms that complicate preoperative diagnosis. Although current evidence questions the need for aggressive treatment in cases without extraovarian extension, we implemented a primary thyroid carcinoma protocol-including total thyroidectomy and radioactive iodine therapy-to minimize recurrence risk.