We successfully established and validated a simple and reliable preoperative prediction model for FTC using the preoperative thyroglobulin level and ultrasonographic features of the thyroid nodules.
We included all patients with well-differentiated FTC who underwent total thyroidectomy and radioactive iodine (RAI) treatment without neck structural disease at the time of RAI and with Tg and US at least 6 months after RAI.
PET using the radiotracer F-fluorodeoxyglucose (FDG) was performed in a patient who presented with elevated thyroglobulin (Tg) levels several years after initial therapy of follicular thyroid carcinoma (oncocytic variant) and in whom high-dose radioiodine (I) failed to locate recurrent tumor or to decrease Tg levels.
The serum Tg (odds ratios (OR) 10.311, p < 0.001) and tumor volume (OR 4.500, p = 0.035) were found to be independent predictors for FTC in all patients with a cytological diagnosis of follicular lesion.
Histologically, the tumor had striking follicles with dense, colloid-like material resembling thyroid follicular carcinoma while the tumor cells were negative for thyroid markers (thyroglobulin and thyroid transcription factor-1).
Post-thyroidectomy Tg levels are apparently associated with prognosis of papillary and follicular thyroid carcinomas and may predict tumor recurrence and metastastic potential.
In addition, thyroglobulin mRNA expression was markedly downregulated (50- to 100-fold) in FTC, PTC and GD samples compared with benign nodular and normal thyroid tissues.