Unusual Presentation of Hurthle Cell Carcinoma With TENIS Syndrome as Left Atrial Thrombus on 18F-FDG PET/CT

Differentiated thyroid cancer (DTC) with thyroglobulin elevation and negative I scintigraphy (TENIS) syndrome is a diagnostic and therapeutic dilemma. Treatment of differentiated thyroid cancer has an excellent outcome, but treatment options in TENIS are limited with the exception of surgically amenable disease. We present a case of TENIS syndrome with incidental detection of tumor thrombus in right pulmonary vein extending to the left atrium on F-FDG PET/CT and subsequently complicating as an occipital bleed. The timely detection of the thrombus facilitated early initiation of anticoagulant therapy. However, the intracranial bleed precluded the continuation of anticoagulant therapy.