Successful Management and Long-term Survival of Malignant Struma Ovarii with Radioactive Iodine Therapy.

Struma ovarii (SO) is a rare ovarian teratoma with predominant thyroid tissue. Malignant SO (MSO) occurs in 5%-10% of cases, with papillary and follicular thyroid carcinomas being the most common malignant types. The disease is typically diagnosed in women aged 40-60 years, and management protocols are not well defined due to its rarity. We report the case of a 37-year-old female who initially presented with vague abdominal pain and a complicated right ovarian cyst and who underwent right oophorectomy. Histopathology confirmed SO. Two years later, she experienced a recurrence with elevated cancer antigen 125 levels and a new left adnexal mass. The surgical intervention included total abdominal hysterectomy, with left Salpingo-ophorectomy and laparotomy revealing disseminated disease. A total thyroidectomy showed no malignancy, and the patient required multiple doses of radioactive iodine (RAI). Over 20 years, she received a cumulative dose of 1250 mCi of RAI and remains asymptomatic with stable disease. MSO is a rare tumor that often requires a combination of surgical intervention and RAI therapy for effective management. This case highlights the importance of a multidisciplinary approach, including surgery and RAI, in managing extensive or recurrent MSO, and provides insights into long-term management and outcomes.