Toluidine blue for the detection of sentinel lymph nodes in patients with thyroid cancer

Introduction
Thyroid cancer (TC) demonstrates steady growth in incidence worldwide and remains an urgent problem in oncology. The detection of sentinel lymph nodes (SLN) with a selective dye and further histological examination in selecting the proper (personalized) surgical strategy and the volume of surgical intervention for clinically undetermined regional lymph nodes. The purpose of the study is to evaluate the effectiveness and safety of intraoperative detection of SLN with a 1% toluidine blue aqueous solution

Material and methods
The significant tasks are to identify the pattern of TC metastases to cervical lymph nodes, to establish the prevalence of “skip” metastases, to compare the frequency of complications after total thyroidectomy and central neck dissection and lateral neck dissection with total thyroidectomy and central neck dissection, and to determine the feasibility of the application of lateral neck dissections in patients with papillary and follicular TC without metastases to regional lymph nodes (according to physical examination and ultrasound).

Results
According to our data the SLN identification rate was 97.6%. Sensitivity, specificity, positive predictive value, negative predictive value, and frequency of false negative and false positive results was 89.2, 94.6, 88.03, 95.16, 10.8, and 5.4%, respectively. The most common metastasis was in the central neck compartment (83.7%). Skip metastases were determined in 4.9% of patients.

Conclusions
The low prevalence of “skip” metastases and a significant risk of postoperative complications (wound exudation, lymphorrhagia, inflammation, hypoparathyroidism, paresis of the vocal cords) support the idea that lateral neck dissection is appropriate only in cases of confirmed metastases by physical examination and/or ultrasound at the preoperative stage.