Metastatic thyroid carcinoma causing superior vena caval obstruction diagnosed on I-131 scan.
An 80-year-old woman was referred for a painless mass arising in right side of her neck of 4 months' duration. Ultrasound revealed a multinodular goiter, but cytology confirmed a follicular carcinoma. Thyroid function was normal. Total thyroidectomy was performed with evidence of tumor infiltration into the strap muscles extending up to the right submandibular gland and right internal jugular vein, which was completely occluded. Radioiodine was considered as the treatment of choice postoperatively. This is an unusual case of SVC obstruction caused by tumor embolus diagnosed on I-131 scan.