Struma ovarii coexisting with mucinous cystadenoma detected by radioactive iodine

The authors describe a case of struma ovarii coexisting with mucinous cystadenoma. Ultrasonography and magnetic resonance imaging showed a multilocular cystic mass with a solid component. The ovarian tumor demonstrated uptake of I-123 sodium iodide, allowing a preoperative diagnosis of struma ovarii. In women with an unexplained increase in thyroid function and low I-123 uptake in the cervical thyroid gland, scintigraphy of the pelvis should be considered.