The clinicopathologic differences of central lymph node metastasis in predicting lateral lymph node metastasis and prognosis in papillary thyroid cancer associated with or without Hashimoto's thyroiditis.

This study aims to evaluate the difference of central lymph node metastases (LNM) in papillary thyroid carcinoma (PTC) associated with or without Hashimoto's thyroiditis (HT) in predicting lateral node metastasis. A retrospective case control study was performed. Patients (1276) with PTC who underwent a total or near-total thyroidectomy with at least one lymph node dissection in our institution were retrospectively reviewed. All patients were divided into two groups (HT-group and non-HT group) according to the pathological diagnosis. In HT-group, the incidence of both central and lateral LNM was lower compared with non-HT group. The average of central metastatic lymph node radio (LNR) was also lower than that in Non-HT group. The multivariate analysis showed that the number of metastatic central LNs (HT ≥ 4, Non-HT ≥ 2) and the central LNR (HT ≥ 0.4, Non-HT ≥ 0.6) were independently associated with lateral LNM. Patients with HT need larger primary tumor size, more positive central LN and higher LNR to predict the presence of lateral LNM. HT may protect against central and lateral LNM in PTC. The number of positive central LNs and central LNR in PTC could be used to determine the presence of lateral LNM and inform postoperative follow-up.