An unusual presentation of struma ovarii mimicking a malignant process.

Abstract

Struma ovarii is a rare form of ovarian neoplasm, composed entirely or predominantly of thyroid tissue. This tumor is generally benign, although malignant transformation has been reported. We report an unusual presentation of a postmenopausal woman with benign struma ovarii associated with a large amount of ascites, a markedly elevated CA 125 serum level, and a large complex pelvic mass thereby mimicking an ovarian cancer. This case serves to remind clinicians that clinical features highly suspicious for ovarian cancer do not necessarily confirm a malignancy.