Malignant struma ovarii with thyrotoxicosis

Background. Malignant struma ovarii is seldom diagnosed preoperatively due to the rarity of the disease itself and the even rarer complications of thy rotoxicosis. Case. A 48-year-old woman presented with symptoms of hyperthyroidism and a pelvic tumor raising the possibility of ovarian malignancy. Hormonal findin gs revealed increased thyroid function, but the thyroid gland was normal in size and texture. Thus, she was diagnosed preoperatively as having a hormo ne-producing malignant struma ovarii. At surgery, a FIGO stage la ovarian p apillary adenocarcinoma of the thyroid was found. An immunohistochemical tu mor stain for thyroglobulin was positive and the ovarian venous thyroglobul in level was extremely high. Findings of hyperthyroidism disappeared over s everal weeks. Conclusion. Malignant struma ovarii can be diagnosed preoperatively. Compli cations of thyrotoxicosis should be kept in mind when evaluating an ovarian tumor. (C) 2001 Academic Press.