*2.2. Preoperative Evaluation*

Preoperative evaluation included clinical history, physical examination, and blood tests to assess thyroid function and autoimmune thyroiditis. Fine-needle aspiration cytology (FNAC) was performed in all patients, and the results were classified according to the Consensus Statement of AIT (Italian Thyroid Association), AME (Medical Endicronologist Associaction), SIE (Italian Endocrinology Association), and SIAPEC-IAP (Italian Society of Pathological Anatomy) for the Classification and Reporting of Thyroid Cytology [25]. Hyperthyroidism status was defined in the case of low serum Thyroid-Stimulating Hormone (TSH) (<0.4 mIU/L), use of thyrostatic drugs or positivity for Anti-TSH receptor antibodies (TRAb). Autoimmune thyroiditis was defined in the case of positivity for anti-thyroglobulin antibodies (Tg-Ab) or anti-thyroid peroxidase antibodies (TPO-Ab) and on the basis of histopathological examination.

High-resolution US of the neck was always performed before surgery by an experienced surgeon, with careful evaluation of the central and the lateral compartment. Preoperative laryngoscopy was routinely performed to assess vocal fold mobility.

Indication for surgery was preoperative cytologic diagnosis or suspicion of DTC or, in the case of negative cytology, the presence of a highly suspicious nodule based on family history, physical examination, and US features of the nodule.
