Abstract
Differentiated thyroid carcinoma rarely involves great veins with tumor thrombosis. Multimodality treatment with surgery, radioiodine therapy and targeted therapies are used for management of tumor thrombus associated with thyroid malignancies, though no established guidelines exist. Authors present a woman of post-operative follicular thyroid carcinoma (FTC) thyroid with tracer avid tumor thrombus in right brachiocephalic vein, treated with 131-iodine (131I) as a single modality for both remnant and tumor thrombus. Her subsequent follow-ups revealed excellent response to treatment.