Detection of Metastases to Internal Jugular Vein and Superior Vena Cava on 131-I Scan

Abstract

Abstract: We report a rare case of a tumor thrombus in the right internal jugular vein (IJV), superior vena cava (SVC), and right subclavian vein due to metastatic thyroid carcinoma, which was detected on an 131-Iodine whole-body scan. A 48-year-old man with a case of follicular variant of papillary carcinoma thyroid was treated twice with high doses of I-131, 188, and 185 mCi (6956 and 6845 MBq respectively), post total thyroidectomy. His post-therapy scan showed an elongated area of I-131 concentration in the right lower neck, which extended to the upper mediastinum Serum thyroglobulin levels were elevated on both occasions to more than 800 ng/mL. As this appeared resistant to radioactive iodine, the patient was referred for surgical management. CT scan was done, which showed a heterogeneously enhancing thrombus in the right IJV, extending to the confluence of the brachiocephalic veins and into the superior vena cava (SVC). A nonenhancing thrombus was also seen in the right subclavian vein. Per-operatively, it was found that the patient had a thrombus in the right IJV, SVC, and right subclavian vein. The patient underwent right IJV thrombectomy with partial resection of the right subclavian vein and repair of the SVC. The histopathology was follicular thyroid carcinoma forming a tumor thrombus in the IJV, SVC, and right subclavian vein. A large dose I-131 scan done 6 weeks postsurgery revealed no abnormal concentration in the whole-body scan. Though the Tg levels were still elevated, it had now decreased to 121 ng/mL.