Clinical Fellow Zucker School of Medicine/Northwell at Lenox Hill Hospital Hicksville, New York, United States
Introduction : Struma ovarii (SO) is a rare ovarian teratoma that predominantly consists of mature thyroid tissue. About 5 to 10% of SO cases are shown to be malignant. Surgical excision is the definitive form of treatment, and radioiodine therapy has been utilized as an adjuvant therapy in metastatic cases.
Case(s) Description : A 25-year-old primigravida patient was found to have a 8.7x5.7x7.8 cm complex right ovarian cyst with a thick, avascular internal septation during her first antenatal visit at 5 weeks. Patient did not follow up until 38th weeks gestation when she requiredan emergent cesarean section for non-reassuring fetal heart tones. During cesarean delivery, a 15 cm partially mucinous and hemorrhagic right ovarian cyst was observed as well as numerous red soft tissue nodules along the cyst surface, uterine fundus, and omentum.Due to high suspicion of peritoneal spread of a metastatic ovarian neoplasm, decision was made to forego cyst extraction to minimize tumoral seeding and large volume hemorrhage.Omental biopsies and pelvic washings were obtained, which demonstrated follicular variant of papillary thyroid carcinoma. Thyroid ultrasound was negative for a mass or nodule.Enhanced computed tomography (CT)revealed a solid/cystic right ovarian mass with multiple abdominopelvic peritoneal implants, ill-defined omental infiltrate, and trace hyper-attenuating pelvic ascites.The patient underwent total hysterectomy, bilateral salpingo-oophorectomy, and tumor debulking of the sigmoid mesocolon, rectal surface, omentum and pelvic wall. Post-surgical specimens confirmed a diagnosis of metastatic follicular variant of papillary thyroid carcinoma.The consensus from a multidisciplinary tumor board was reached to follow the treatment protocol for metastatic primary thyroid cancer. The patient was treated with total thyroidectomy, and surgical pathologyof the thyroid was benign. Radioactive iodine (RAI) treatment was delayed until 3 months after breastfeeding to minimize uptake in the breast tissue. She receivedRAI (I-131) therapy of 200 mCi. Whole body iodine scan following RAI treatment revealed uptake in the areas of known peritoneal metastases. Mild uptake in the neck was consistent with thyroid remnant ablation. Thyroglobulin reduced dramatically from 523ng/ml prior to RAI, to 2.57ng/ml six months post-treatment (with TSH 0.93uIU/mL) on levothyroxine replacement. The follow-up CT scan at 6 months was negative for tumor recurrence or new metastatic disease.
Discussion : We present a case of malignant strumaovarii (MSO) with extensive metastases in a young primigravida patient. Based on limited evidence and lack of consensus regarding management of MSO, therapeutic protocol for primary thyroid carcinoma was utilized. There are limited guidelines regarding extent of the surgery, dosing and safety of RAI, post-operative treatment, duration of follow-ups, and indication for adjuvant therapy in metastatic MSO, especially in the obstetrics population. Since the recurrent rates in the past literature have shown to be variable, we believe long term follow-up with serial imaging, tumor markers and thyroglobulin levels is important.
