SUN-LB81 Coexisting Malignant Struma Ovarii and Cervical Follicular Variant Papillary Thyroid Carcinoma

A 44-year-old woman presented with left lower quadrant abdominal pain for 2 months. Further evaluation revealed a left adnexal mass and she underwent a TAH-BSO. A 12 cm mass arising from the left ovary was resected which on microscopy appeared to be papillary thyroid carcinoma follicular variant arising from a mature teratoma (struma ovarii). A thyroid ultrasound showed two subcentimeter right thyroid nodules without any concerning lymphadenopathy. A total thyroidectomy was then performed to allow her to receive adjuvant RAI. The cervical thyroid pathology showed a 0.6 cm follicular variant papillary thyroid carcinoma with negative margins without angioinvasion, lymphatic invasion or extrathyroidal extension. Thyroid hormone suppression with levothyroxine was started. Preoperatively, thyroglobulin was 1381 ng/ml (nl range 1.3-31.8 ng/ml). After TAH-BSO and thyroidectomy, thyroglobulin was undetectable and so was the anti-thyroglobulin antibody. With an undetectable thyroglobulin level, it was decided not to pursue adjuvant RAI and continue TSH suppression with levothyroxine. Simultaneous existence of malignant struma ovarii and cervical papillary thyroid cancer is rare and has a favorable prognosis compared to metastasis to the ovaries from primary cervical thyroid papillary carcinoma. Due to the rarity of this condition, management is not clear or well supported by evidence. Various approaches are suggested by different authors, including thyroidectomy after resection of malignant struma ovarii to facilitate adjuvant RAI, only performing surgical resection of the ovarian tumor in the absence of high risk features or performing thyroidectomy and RAI only in metastatic or recurrent disease. References:1.Aaron Leong, Philip J. R. Roche, Miltiadis Paliouras, Louise Rochon, Mark Trifiro, Michael Tamilia, Coexistence of Malignant Struma Ovarii and Cervical Papillary Thyroid Carcinoma, The Journal of Clinical Endocrinology & Metabolism, Volume 98, Issue 12, 1 December 2013, Pages 4599-46052.Synchronous malignant struma ovarii and papillary thyroid carcinoma Pablo Fernández Catalina,Antonia Rego Iraeta, Mónica Lorenzo Solar, Paula Sánchez Sobrino DOI: 10.1016/j.endoen.2016.08.006