Recurrent thyrotoxicosis of extrathyroidal origin due to struma ovarii: A case report and review

Abstract

Struma ovarii (SO) is a recognized, albeit infrequent, cause of ectopic thyroid hormone secretion. Due to its rarity, only a few cases had been reported with fairly detailed information on thyroid function test (TFT) results. Furthermore, data are limited in the extent of local spread, surgical approach, and postoperative management. A 41-year-old woman from Libya presented with tremor, nervousness, weight loss, heat intolerance, and palpitation. She had also complained of lower abdominal pain and delayed periods. Two years earlier, she was diagnosed with hyperthyroidism, treated with a 12-month course of antithyroid medications resulting in full resolution of symptoms. Her TFTs revealed elevated serum triiodothyronine, thyroxine (T4), free T4, and low thyroid-stimulating hormone (TSH). Pelvic ultrasonography showed a left ovarian cystic mass and a suspicious of ectopic pregnancy was suggested. Abdominal surgical exploration with left salpingo-oophorectomy was performed. Gross and microscopic examinations confirmed the diagnosis of SO. Four weeks later, TFTs were repeated and revealed a high level of serum TSH, and low total T4 and free T4 levels. L-thyroxine replacement was started. In conclusion, Determination of the cause of thyrotoxicosis is essential for proper management. If clinical data and initial investigations are not consistent with common causes of hyperthyroidism, whole-body radioactive iodine scan should be considered. The definitive treatment for patients with SO is surgical resection via laparoscopic approach.