(86) Ovarian Torsion of a Struma Ovarii in an 18-Year-Old with Hyperthyroidism

Background: Struma ovarii is a rare type of ovarian monodermal teratoma, comprising 1% of all ovarian tumors. Struma ovarii contain thyroid tissue, however evidence of hyperthyroidism is present in only 5-8% of patients. The objective of this report is to present an unusual case of a patient with ovarian torsion secondary to a large struma ovarii teratoma and evidence of hyperthyroidism, and to review the diagnosis and management of these tumors.

Case: The patient is an 18-year-old who presented with acute left lower quadrant pain. Computed tomography showed a 9.2 x 6.5 x 10.1 cm pelvic mass with solid, fat, and calcified components, consistent with teratoma. Ultrasound confirmed a complex left ovarian lesion and normal color Doppler flow in both ovaries. The patient was tachycardic throughout her evaluation, which was attributed to pain and a reported history of Graves’ disease. After discussion with the patient and her family, the decision was made to proceed to the operating room for a diagnostic laparoscopy due to concern for ovarian torsion.
Intraoperatively, the left ovary and fallopian tube were found to be torsed, with significant edema and discoloration of both structures. Detorsion and left salpingectomy were performed laparoscopically. Separation of the cyst from the ovarian parenchyma and removal of specimens were done via a mini-laparotomy incision due to the impressive size of the cyst and hyperemic tissue precluding visualization with the laparoscope. During placement of a uterine manipulator, the patient was also noted to have a septate hymen and a wide, flat uterus suggestive of possible uterine anomaly. The patient’s postoperative course was uncomplicated.
Gross pathologic exam of the specimen revealed an ovoid, unilocular cystic structure with friable tissue, hair, and a tooth. Microscopically, the tumor was identified as a mature cystic teratoma with prominence of benign thyroid tissue and hemorrhage consistent with torsion.

Comments: Surgical resection is the recommended management for benign struma ovarii larger than 5 cm. Additionally, surgical resection was recommended in this case due to suspected torsion of the adnexal structures. However, there are additional considerations in patients with concomitant hyperthyroidism that require careful perioperative and intraoperative monitoring. Surgery can precipitate a potentially lethal thyrotoxicosis, leading to cardiac arrythmia, hyperthermia, or cardiovascular collapse. Patients with known hyperthyroidism should have their thyroid hormone levels optimized prior to surgery, although this may not be possible if emergent surgery is needed, as in this case.