Prediction of cervical lymph node metastases in papillary thyroid microcarcinoma by sonographic features of the primary site

OBJECTIVE: To study the sonographic features of the primary site of papillary thyroid microcarcinoma (PTMC) for the prediction of cervical lymph node metastasis during preoperative diagnosis. METHODS: A total of 710 PTMC patients between 2013 and 2016 with a diagnosis of cervical lymph node metastases were reviewed. We analyzed the sonographic features of the PTMC primary site to predict ipsilateral or central lymph node metastases in univariate and multivariate models. The ratio of abutment/perimeter of the PTMC primary site was utilized to evaluate cervical lymph node status. RESULTS: Regarding clinical characteristics, multifocality and extrathyroidal extension were associated with cervical lymph node involvement. In the multivariate regression model, calcification and the abutment/perimeter ratio of lesions were evaluated as independent factors in level VI, ipsilateral or skip cervical lymph node metastases. The cut-off value of the ratio of abutment/perimeter of the PTMC primary site (25%) was significantly correlated with cervical lymph node metastases (P = 0.000). CONCLUSIONS: Independent sonographic features, including lesion size, lesion location, calcification, and the ratio of abutment/perimeter of the primary site, were associated with cervical lymph node metastases in PTMC patients.