Sentinel lymph node biopsy may be used to support the decision to perform modified radical neck dissection in differentiated thyroid carcinoma

Background: The prognostic significance of lymph node metastases (LNM) in follicle cell-derived differentiated thyroid carcinoma (DTC) is still controversial. The management of cervical lymph nodes varies from "berry picking" to modified radical neck dissection (MRND). The incidence of LNM in papillary thyroid carcinoma varies from 27% to 80%. The importance of sentinel lymph node (SLN) biopsy for decisions about the surgical management of lymph nodes in DTC has been the subject of several previous studies. Patients and Methods: In 40 patients with DTC methylene blue dye was applied peritumorally. Both SLN and non-SLN in the lower third of the jugulo-carotid chain were dissected prior to total thyroidectomy and routine dissection of the central neck compartment and examined by frozen-section and standard histology. MRND was performed in 9 cases of LNM in the lateral neck compartment. Results: The SLN identification rate was 92.5%. Metastases in SLNs were revealed by frozen-section histology in 7 cases, leading to immediate MRND. The findings were confirmed on standard HE examination. In 2 false-negative cases SLN metastases were revealed on standard histology and MRND was performed 1 week later. The specificity of the method was 100%, sensitivity 77.7%, negative predictive value 94%, positive predictive value 100%, with overall accuracy of 95%. Conclusion: Our results seem to imply that SLN biopsy in the jugulo-carotid chain using methylene blue dye mapping may be a feasible and valuable method for estimating lymph node status in the lateral neck compartment. It may be helpful in the detection of true-positive but nonpalpable lymph nodes, and in such cases may support the decision to perform MRND in patients with DTC.