BRAF and metastatic malignant neoplasm in the lymph nodes: In this study, we enrolled 250 patients with cN0 PTC to receive ultrasound-guided fine-needle aspiration cytology (US-FNAC) combined with BRAF V600E mutation detection, so as to identify the potential application value of US-FNAC with BRAF V600E mutation detection in assessing central neck lymph node metastasis in cN0 PTC, in order to provide reliable molecular evidence to use it for preoperative evaluation, operation procedure design, and postoperative follow-up planning in the clinic.