Disease management of malignant struma ovarii.

Objective: Ovarian goiter that meets the diagnostic criteria for malignant thyroid tumors or has invasive distant metastasis is called malignant struma ovarii (MSO). The incidence of MSO is very low. The level of serum thyroglobulin (Tg) is helpful to differentiate MSO with highly differentiated pathological type from other ovarian malignancies. But its therapeutic method is currently debated. Herein, we present a case of 54 years old woman, who was admitted to hospital due to frequent abdominal pain for 9 months and with normal serum Tg. Postoperative pathological examination revealed highly differentiated follicular thyroid carcinoma of bilateral ovarian origin, which penetrated bilateral ovarian cortex, involved the serosal surface of left fallopian tube and disseminated to sigmoid mesentery, small intestinal mesentery and pelvic cavity. The disseminated lesions were considered to originate from right ovary. After the total thyroidectomy, iodine-131(¹³¹I) treatment was performed with a dose of 150mCi. The ¹³¹I whole-body scintigraphy (WBS) 2 days after treatment showed residual thyroid tissue in the neck and implantation metastasis in mesentery. After 1-year regular follow-up, no significant abnormalities were found in tumor indicators, Tg, thyroid function, neck ultrasound and abdominopelvic enhanced computed tomography (CT). This MSO case with normal Tg and multiple implantation metastasis aimed to discuss its clinical management especially for Tg and ¹³¹I and to improve its prognosis.