Lateral neck multilevel fine‐needle aspiration cytology and thyroglobulin estimation in papillary thyroid carcinoma

OBJECTIVE: To assess the accuracy of preoperative ultrasound‐guided multilevel fine‐needle aspiration (FNA) cytology and thyroglobulin (Tg) estimation in mapping metastatic levels in the lateral neck, in patients with papillary thyroid carcinoma (PTC). METHODS: Patients with PTC clinically metastasizing to the lateral neck who were initially treated at the Peking University Cancer Hospital from June 2018 to September 2020 were included. FNA was performed preoperatively in each suspicious neck level; cytological examination (FNA‐C) and Tg measurement of the needle‐washout fluid (FNA‐Tg) were combined to determine metastasis. FNA‐Tg cutoff value was calculated, and the accuracy of FNA at different levels were evaluated. RESULTS: In total, 111 patients underwent 124 lymph node dissections. The best cutoff value of FNA‐Tg for the diagnosis of metastatic level was 1.0 ng/mL. Multilevel FNA showed sensitivity, specificity, positive predictive value, and negative predictive value in predicting single‐level metastasis of 100%, 61.0%, 43.9%, and 100%, respectively. In 64 (51.6%) cases, the involved levels diagnosed by FNA were consistent with that diagnosed by postoperative pathology. CONCLUSION: FNA‐Tg improves the diagnostic performance of FNA‐C in lateral neck lymph node metastases. However, limited accuracy was obtained for preoperative multilevel FNA in predicting the extent of metastasis in the lateral compartment.