Figure 4. Ultrasonographic images of selected patients with PTC undergoing active surveillance.

(A) Eleven mm PTC with posterior localization adjacent to the trachea and duplication of Tg serum levels in less than one year. Active surveillance was previously agreed due to a high surgical risk. The patient underwent surgery after 12 months of follow-up with a low risk of recurrence tumor and an excellent response to treatment after 32 months of follow-up; (B-D) Markedly hypoechoic thyroid nodules with macro and microcalcifications and irregular margins (Bethesda category VI). Tumor size remained stable under active surveillance (12, 5 and 12 mm respectively) after 84, 30 and 53 months, respectively.