A Rare Case of TENIS Presenting with SVC Thrombus - Highlighting the Role of PET-CT scan

Thyroglobulin-elevated negative iodine scan (TENIS) syndrome represents a significant diagnostic and therapeutic challenge. Highly sensitive imaging modalities are required to help in the localization of disease, treatment planning, and prognostication. When compared to other imaging modalities, F-18 fluorodeoxyglucose positron-emission tomography–computed tomography has superior sensitivity and specificity in localizing the disease in this subset of patients. Tumor thrombus of thyroid cancer extending into the great vein is a very rare occurrence and management criteria have not been well established yet. We present a case of TENIS syndrome with tumor thrombus in the superior vena cava.