Predictive Factors for Lateral Lymph Node Metastasis and Skip Metastasis in Papillary Thyroid Carcinoma

In papillary thyroid cancer (PTC) patients, cervical lymph node metastases are common, which disseminate sequentially from the central neck to the lateral neck. However, there is also a chaotic pattern of lymph node metastasis occasionally. In this study, we summarized 653 PTC patients who underwent thyroidectomy and central lymph node dissection with or without lateral lymph node dissection from two hospitals to investigate the pattern and risk factors of lateral lymph node metastasis (LLNM) and skip metastasis. LLNM was significantly associated tumor size > 1 cm, presence of extrathyroidal extension, tumors in the upper-lateral pole, and the number of metastatic lymph nodes in the central compartment. The frequency of skip metastasis was 22.5% (20 of 89 patients). Multivariate analyses showed tumor size ≤ 1 cm, and tumors in the upper-lateral pole were separately and independently associated with the risk of skip metastasis. Presence of LLNM affected the recurrence-free survival (RFS). RFS did not show the significantly difference between patients with LLNM and skip metastasis. Despite the low incidence of skip metastasis, attention should be paid to the possibility of LLNM even in the absence of central lymph node metastases. Besides, for patients with risk factors of LLNM or skip metastasis, detailed preoperative examination for the lateral compartment, especially the level III, is essential.