An unusual presentation of the TENIS syndrome

IntroductionPapillary carcinoma is the commonest subtype of thyroid cancer. Patients are treated with radioactive iodine (RAI), and monitored with RAI scans, serum thyroglobulin levels, and cervical ultrasonography. Elevated serum thyroglobulin despite a negative RAI scan is termed the TENIS syndrome (Truncated Expression of the NIS; NIS represents the sodium-iodide symporter). Alternative imaging is then indicated.Method/ResultA female Caucasian patient with papillary thyroid carcinoma had been followed up at our Thyroid Cancer clinic. A diagnostic scan revealed residual thyroid tissue. RAI ablation of the thyroid remnant was performed with 80 mCi of RAI. Two- and five-year follow-up scans were clear. However, thyroglobulin levels remained high, thus a diagnosis of TENIS syndrome was made.An F-18 FDG PET/CT scan was performed which demonstrated inhomogeneous liver uptake (SUV > 6). Abdominal CT confirmed multiple liver lesions; ultrasound-guided FNA of these revealed several groups of malignant cells.ConclusionPersistently elevated thyroglobulin levels in the presence of a negative whole-body RAI scan are of great concern. In this patient with unusual liver metastases from papillary thyroid cancer, and relatively low thyroglobulin levels despite significant metastases, F-18 FDG PET/CT has once more proved its efficacy in the evaluation of patients with the TENIS syndrome.