Risk Factors for Bilateral Lateral Lymph Node Metastasis in Unilateral Papillary Thyroid Cancer

Objective: This study investigated the factors associated with bilateral lateral lymph node (LN) metastasis in patients with unilateral papillary thyroid cancer.Methods: The records of the patients who underwent total thyroidectomy with bilateral lateral neck dissection from 2009 to 2020 were investigated. Clinicopathologic characteristics of eligible patients were examined.Results: Of 11 eligible patients, 72.8% had the primary tumor larger than 2 cm (18.2% larger than 4 cm), and central compartment metastasis was present in all patients at the time of the surgery. On the other hand, aggressive subtype, extranodal extension, and lymphovascular and perineural invasion were not identified in most of the patients. Furthermore, preoperative sonography detected all possible contralateral LN metastasis, while computed tomography missed contralateral metastasis in 1 patient.Conclusion: A meticulous evaluation for contralateral LN metastasis using sonography is needed in unilateral papillary thyroid cancer patients with high risk factors.