Comparison of Ultrasound Features of Primary Metastatic Papillary Thyroid Carcinoma and Recurrent/Persistent Metastatic Cervical Lymph Nodes.

Objective To explore the ultrasound features and levels of cervical lymph node metastases in primary and recurrent/persistent papillary thyroid cancer (PTC).Methods We retrospectively analyzed the clinical data of 2181 patients who underwent cervical lymph nodes dissection for PTC from January 1(st) 2015 to January 1(st) 2016.Totally 418 PTC patients (with 622 lymph nodes) who met the inclusion criteria entered the final analysis.Patients who had not received any prior thyroid treatment (surgery with or without radioactive iodine) were categorized as the primary group (352 patients with 527 metastatic lymph nodes),and patients who had received prior treatment (thyroidectomy with or without radioactive iodine) for PTC were categorized as recurrent/persistent group (66 patients with 95 metastatic lymph nodes).Pathological results from lymph node dissections were used as the gold standards by means of level-to-level analysis.Results The mean of the minimum axis diameter of the lymph nodes in the primary group was (6.7±3.6)mm,and that of the recurrent/persistent group was (6.6±3.1)mm (U=0.180,P=0.857).The proportion of metastasis in the central area of primary group was 40.0%,which was significantly higher than that in the recurrent/persistent group (12.6%);the proportion of metastasis in the lateral area was 60.6% in the primary group,which was significantly lower than that in the recurrent/persistent group (87.4%)(χ(2)=26.288,P<0.001).In lateral metastatic lymph nodes,Ⅲ level was the most common place in both groups.Level Ⅴ metastatic lymph was rare in both primary group and recurrent/persistent group.Calcifications (63.1% vs. 48.2%;χ(2)=7.207,P=0.007) and peripheral vascularity (81.1% vs. 59.4%;χ(2)= 16.147, P<0.001) were more common in the recurrent/persistent group.The round shape,absence of an echogenic hilum,hyperechogenicity,and cystic aspects were not significantly different between these two groups (all P>0.05).Conclusions Primary metastatic lymph nodes often occur in the central area of lymph nodes,while lateral metastatic lymph nodes are more common in recurrent/persistent PTC.For metastatic lymph nodes,calcifications and peripheral vascularity are more common in recurrent/persistent PTC.