Hyperthyroidism associated with struma ovarii - a case report and review of literature

Hyperthyroidism is a state characterized by elevated serum level of thyroid hormones: thyroxine (T4) and triiodothyronine (T3). This is mainly related to the condition and functioning of the thyroid gland. In 60-80% of cases elevation of these hormones are caused by Grave's disease. Thyrotoxicosis is an extreme presentation of hyperthyroidism which can, in rare cases, be caused by excessive synthesis of thyroxine by tumor cells. Struma ovarii is a rare ovarian teratoma composed of thyroid tissue in more than 50%.

To present a case of a 30-year-old female patient with a past history of Grave's disease treated by strumectomy 7 years prior; now presenting for the assessment of secondary amenorrhea. Pelvic ultrasound revealed bilateral solid tumors on the left and right ovary, respectively measuring 5 cm and 6 cm in diameter. Her clinical presentation was suggestive of overt hyperthyroidism, and she presented with a significantly elevated CA-125 (152.7 U/mL).

The patient subsequently underwent a bilateral oophorectomy in which both masses were excised and histopathological examination confirmed teratoma maturum cysticum. Struma ovarii was noted as a component of the left ovary teratoma.

Establishing a proper diagnosis of hyperthyroidism and elucidating its origin is often challenging. Struma ovarii is a rare cause of hyperthyroidism but should always be considered in case of treatment resistant hyperthyroidism. This case-report lends itself as an example of the value in maintaining gynecological-endocrinological knowledge in the setting if clinical gynecology.