The dilemma of managing thyroid gland after incidental diagnosis of malignant struma Ovarii. Is radical thyroidectomy and radioactive iodine Necessary? A case report and literature review

•Struma ovarii is a rare ovarian teratoma which consists of at least 50% thyroid tissue.•In 0.5–1% of cases the thyroid tissue in the struma ovarii undergoes a malignant transformation.•Patients should be divided into low and high-risk groups for synchronous thyroid carcinoma.•Patients with abnormalities on thyroid imaging should be considered as high-risk.•A thyroidectomy and radioactive iodine treatment can decrease the risk of recurrence.