Thyroglobulin Elevation with No Uptake on Radioiodine Scan (TENIS)

Abstract

A 61-year-old man presented with a right thyroid solitary thyroid nodule which was present for the last 6 years but had recently increased in size. On examination, he had a 7 × 6 cm swelling in the right thyroid lobe without any palpable LAP. FNAC was suspicious of MTC but his serum calcitonin turned out to be normal (5 pg/ml). He underwent TT+ CCLND. HPE revealed papillary carcinoma thyroid, pT2N0 (right lobe, multifocal, 4 cm, No ETE, 0/12). Post-Operative Course showed normal Tg levels—1.01 ng/dl, ATG—<20 IU/ml and WBRAI scan showed uptake in the right thyroid bed remnant for which he received 65 mCi of RAI for ablation. Post therapy scan showed increased tracer uptake in the left thyroid bed & paratracheal region. He was started on Levothyroxine 200 μg OD and was on regular follow-up. One year later he presented with a left neck recurrent LN which on CECT neck was a 3.6 × 2.0 cm enhancing lesion in the left paratracheal region. Guided FNAC was suggestive of metastatic PTC. At that time his Tg levels were 22.8 but his WBRAI was negative and PET scan revealed a left paratracheal uptake. Selective LN dissection was done. Subsequently, his Tg started rising. At Tg level of 22.8 his WBRAI was negative. He was kept on follow-up and after 1 year after which his Tg levels were 243 ng/dl with ATG levels—<20 IU/ml. However, his WBRAI scan was negative. 18F-FDG PET showed left supraclavicular mass with multiple mediastinal LN and non-FDG avid multiple pulmonary nodules (Figs. 1, 2, and 3).

Amit Agarwal is the lead author of this chapter.