Ultrasonographic Indeterminate Lymph Nodes inPreoperative Thyroid Cancer Patients: Malignancy Riskand Ultrasonographic Findings Predictive of Malignancy

ABSTRACT

Objective@#Proper management of lymph nodes (LNs) with ultrasonographic (US) indeterminate features in thyroid cancerpatients remains elusive. We aimed to evaluate the malignancy risk and US findings predictive of malignancy for USindeterminate LNs in preoperative thyroid cancer patients through node-by-node correlation. @*Materials and Methods@#A total of 348 LNs in 284 thyroid cancer patients, who underwent fine-needle aspiration or coreneedlebiopsy between December 2006 and June 2015, were included. We determined the malignancy risks for US probablybenign, indeterminate, and suspicious categories. For US indeterminate LNs, which had neither echogenic hilum nor hilarvascularity in the absence of any suspicious finding, US findings were compared between benign and metastatic LNs usingMann-Whitney U test and Fisher’s exact test. @*Results@#US imaging diagnoses were probably benign in 20.7% (n = 72) cases, indeterminate in 23.6% (n = 82), andsuspicious in 55.7% (n = 194). Malignancy risk of US indeterminate LNs (19.5% [16/82]) differed from those of the USprobably benign (2.8% [2/72]) (p = 0.002) and US suspicious LNs (78.4% [152/194]) (p < 0.001). Among US indeterminate LNs,there were no significant differences in short, long, and long-to-short diameter (L/S) ratios between benign and metastatic LNs(3.9 vs. 3.8 mm, p = 0.619; 7.3 vs. 7.3 mm, p = 0.590; 1.9 vs. 1.9, p = 0.652). @*Conclusion@#US indeterminate LNs were frequently encountered during preoperative evaluation and had intermediate malignancyrisk. Given the lack of discriminative power of size criteria and L/S ratio, clinical factors such as surgical strategy and nodesize should be considered for proper triage of US indeterminate LNs in thyroid cancer.