Hashimoto thyroiditis as a manifestation of struma ovarii

We describe clinicopathologic features, laboratory data, and imaging and therapeutic management of a rare case of Hashimoto thyroiditis arising in struma ovarii. The patient was a 38-year-old woman with clinical symptoms of hyperthyroidism. Laboratory data showed elevated levels of total and free thyroxine, low thyrotropin level, and positive specific antithyroid antibodies without ultrasound evidence of morphologic abnormalities of the thyroid gland. Pelvic ultrasonography and magnetic resonance imaging of the abdomen showed bilateral solid ovarian masses containing cystic and fat areas diagnostic of teratoma. The performance of a I whole-body scan demonstrated a focus of intense uptake in the pelvis with minimal residual thyroid gland. The patient had a bilateral oophorectomy, and histologic examination revealed thyroid tissue in both masses with all the features of Hashimoto thyroiditis in the right ovary. Symptoms of hyperthyroidism diminished after the surgery, and the thyroid hormone levels and antithyroid antibodies were in the normal range in 1 month. The present case further confirms the rare occurrence of Hashimoto thyroiditis in struma ovarii. This diagnosis should be suggested in the differential diagnosis of patients with symptoms of thyroid disease and a normal thyroid gland. Copyrigh © 2010 by Lippincott Williams & Wilkins.