SUN-607 Chronic Tumor Thrombus in Follicular Thyroid Cancer: A Case Report

Background: Prevalence of tumor thrombus associated with thyroid cancer has been reported to be 0.2-3.8% . Tumor thrombus has been seen in follicular, Ḧurthle, papillary, insular and anaplastic thyroid cancers. Follicular and Ḧurthle cell carcinomas are the most common forms of thyroid cancer associated with tumor thrombus, as they pose angioinvasive features and can spread by direct extension. Determining the presence of tumor thrombi in all patients with thyroid masses has an important clinical significance as it helps in the planning of operative procedure and prevents misdiagnosis of venous thrombus. Total thyroidectomy with thrombectomy or segmental resection of the internal jugular vein is recommended for management. Case report: A 72 year old lady underwent removal of her left thyroid lobe in the 1990s with benign pathology. In 2005 she had biopsy of a right thyroid nodule which was negative for malignancy. She presented to our clinic in October of 2006 for follow up of the thyroid nodule. Thyroid ultrasound showed a 2.8 cm nodule in the midpole and 2 cm nodule in the lower pole of the right thyroid lobe and a lobulated, extremely hypervascular mass that arose from the upper pole and extended laterally and into the right internal jugular vein. Fine needle aspirate of the larger thyroid nodule and extra thyroidal mass were consistent with benign thyroid nodules. TSH was 2.16 mIU/L (n 0.3- 4.2 mIU/L) and thyroglobulin was 4306 ng/mL (athyrotic < 0.1, intact thyroid ≤ 33 ng/ml). The patient was lost to follow up until 2014. She underwent fine needle aspiration of two right thyroid nodules; one of the results was suspicious. In June of 2014, she underwent thyroidectomy elsewhere. Pathology showed a well-differentiated follicular carcinoma. After the surgery, she was treated with radioactive iodine after Thyrogen stimulation, and a whole body scan showed intense localization in the thyroid bed, but nowhere else. TSH = 0.24 mIU/L, thyroglobulin antibody was negative and thyroglobulin tumor marker was 589 ng/mL. An ultrasound of the neck showed a non-occlusive tumor thrombus measuring 6.2 x 1.0 x 1.3 cm within the right internal jugular vein. She underwent removal of right internal jugular vein and tumor in March of 2015. Pathology showed right internal jugular vein with tumor consistent with metastatic thyroid follicular carcinoma. Post operatively, TSH = 0.2 mIU/L, thyroglobulin antibody was negative and thyroglobulin decreased from 589 ng/mL to 3.9 ng/mL. Conclusion: We present this 72 year old lady with follicular thyroid cancer and chronic well localized tumor thrombus in the right internal jugular vein that was present for at least 9 years. Thyroid tumor thrombus was accounting for substantial elevation of thyroglobulin that was persistent after she underwent total thyroidectomy. She underwent removal of right internal jugular vein and thyroid tumor with significant reduction in thyroglobulin level.