Struma ovarii complicating pregnancy: a case report.

Struma ovarii represents an ovarian mature teratoma with thyroid tissue comprising more than 50% of the ovarian tumor. It is a rare condition, representing approximately 1% of all ovarian tumors with a potential malignant transformation 5% to10%. When it is combined with pregnancy, it renders its management in this circumstance is extreme challenging. The authors present a case of benign struma ovarii diagnosed as a right adnexal mass during first trimester of pregnancy with an uneventful clinical course.