Diagnostic Algorithm for Metastatic Lymph Nodes of Differentiated Thyroid Carcinoma
Sae Rom Chung, Jung Hwan Baek, Young Jun Choi, Tae‐Yon Sung, Dong Eun Song, Tae Yong Kim, Jeong Hyun Lee
Abstract
We aimed to evaluate appropriate strategies for interpreting fine-needle aspiration cytology (FNAC) and thyroglobulin concentrations obtained through aspiration (FNA-Tg) results based on the sonographic features of lymph nodes (LNs). Consecutive patients who underwent ultrasound-guided FNAC and FNA-Tg for metastatic LNs from differentiated thyroid carcinomas (DTCs) from January 2014 to December 2018 were reviewed retrospectively. LNs were categorized sonographically as suspicious, indeterminate, or benign. The optimal FNA-Tg cutoff for metastatic LNs was evaluated preoperatively, after lobectomy, and after total thyroidectomy. The diagnostic performances of FNA-Tg, FNAC, and their combination were analyzed based on the sonographic features of LNs. The malignancy rates of LNs were analyzed based on the sonographic features, FNAC, and FNA-Tg results. Of the 1543 LNs analyzed, 528 were benign, whereas 1015 were malignant. FNA-Tg increased the sensitivity and accuracy of FNAC for LNs. The malignancy rate of LNs found to be malignant by FNAC or elevated FNA-Tg ranged from 82% to 100%, regardless of the sonographic features. The malignancy rate of LNs with indeterminate or benign FNAC findings and low FNA-Tg were stratified according to their sonographic features. We propose a diagnostic algorithm, based on combined FNAC, FNA-Tg, and ultrasound features of LNs, for diagnosing metastatic LNs of DTCs.