TG and differentiated thyroid carcinoma: Serum thyroglobulin levels should be regularly measured, as t elevated levels may indicate recurrence or metastatic progression.[10] Compared to papillary thyroid carcinoma, FTC exhibits a higher recurrence rate and worse prognosis, particularly in the presence of undifferentiated components.[11] Thus, long-term follow-up is essential to detect recurrence early and manage metastases effectively.