Malignant struma ovarii: two case reports and a review of the literature.

Struma ovarii consists of thyroid tissue derived from germ cells in a mature teratoma. Malignant transformation is very rare, with clinically evident metastatic disease reported in approximately 20 cases. The rarity of this disease renders evaluation of treatment modalities difficult. There is evidence that these tumors behave like their thyroid counterparts, and cytoreductive surgery followed by ablation with radioactive iodine has been advocated. We report the diagnosis and treatment of 2 patients with metastatic malignant struma ovarii treated with a combination of surgery and radiation therapy.