Predictors of metastasis to lymph nodes posterior to the right recurrent laryngeal nerve in differentiated thyroid carcinoma: A prospective study

Objectives: To study the clinicopathological characteristics and the risk factors of lymph nodes posterior to the right recurrent laryngeal nerve (LN-prRLN) metastasis in differentiated thyroid carcinoma; and to identify the indication for LN-prRLN dissection. Methods: We treated 145 patients with differentiated thyroid carcinoma with appropriate surgical intervention. The specimens were examined by the pathologists. The right paratracheal lymph nodes were divided into two groups: anterior or posterior to right recurrent laryngeal nerve (VIa or VIp compartment, respectively). We recorded the clinical characteristics, histopathological features of the primary tumors, and lymph node metastasis of the patients. The results were statistically analyzed. Results: There were 85 patients (58.6%) with central lymph node metastasis, of whom 61 (42.1%) had metastasis in VIa compartment; 16 patients (11.0%) had VIp subdistrict metastasis; and 25 patients had lateral lymph node metastasis. Multiplicity, larger tumor (>= 1 cm), and coexistence of central lymph node metastasis, VIa compartment metastasis, and lateral lymph node metastasis were all significantly related with LN-prRLN metastasis, while sex, age, location of the tumor, and extrathyroid extension of the tumor showed no significant relation (p > 0.05). Conclusion: The incidence of LN-prRLN metastasis was lower than other central lymph nodes, as well as lymph nodes anterior to right recurrent laryngeal nerve. When there were multiple foci of tumors, or the tumor was larger than 1 cm, or central or lateral LN metastasis was indicated by preoperative ultrasound or confirmed by intraoperative frozen sections, it is strongly recommended that exploration and dissection of the LN-prRLN should only be performed by experienced surgeons. (C) 2016 Asian Surgical Association and Taiwan Robotic Surgical Association. Publishing services by Elsevier B.V.