Clinical Efficacy of Sentinel Lymph Node Biopsy Using Methylene Blue Dye in Clinically Node-Negative Papillary Thyroid Carcinoma

Sentinel lymph node biopsy (SLNB) has recently been used to detect occult lymph node metastases. The aim of this study was to assess the feasibility and clinical efficacy of SLNB in the treatment of clinically node-negative papillary thyroid carcinoma. A total of 114 consecutive patients with clinically node-negative papillary thyroid carcinoma were enrolled and underwent SLNB. After injection of 1% methylene blue around the tumors, blue-stained sentinel lymph nodes (SLN) were collected from the central compartments. All the patients underwent total thyroidectomy with bilateral central compartment neck dissection after SLNB. SLN were identified in 84 (73.7%) of the 114 patients. Of these 84 patients, 24 (28.6%) had metastases in the SLN. Among the 60 patients who had no metastases in their SLN in frozen biopsy samples, seven had metastatic foci in their SLN in the permanent biopsy samples and six had metastases in their non-SLN samples. Central compartment lymph node metastases were detected in 11 of the 30 patients in whom SLN were not identified. Thus, the sensitivity, specificity, and positive and negative predictive values of SLNB were 64.9, 100, 100, and 78.3%, respectively. The false-positive and false-negative rates were 0 and 35.1%, respectively. The detection of SLN led to no major complications. SLNB using methylene blue in papillary thyroid carcinoma is a safe and technically feasible procedure. However, it is of limited use in the management of clinically node-negative papillary thyroid carcinoma because of low sensitivity and a high false-negative rate.