The proliferation activity of the tumor cells shown by Ki-67 LI significantly correlates with aggressive characteristics of PTC, including, an older age, advanced stage, lymph node metastasis, distant/organ metastasis, aggressive histological subtypes, unencapsulated tumors, LVI, ETE, and BRAFV600E mutation. Here, MKI67 is linked to metastatic malignant neoplasm in the lymph nodes.