Sentinel lymph node biopsy in clinically node negative patients with papillary thyroid carcinoma

The incidence of histologically proven lymph node metastases (LNM) in papillary thyroid carcinoma (PTC) reaches 80%. According to different guidelines surgical management in clinically N0 (cN0) patients with PTC remains controversial. The purpose of this study was to investigate if sentinel lymph node biopsy (SLNb) using methylene blue dye is accurate in the detection of LNM in the lateral neck compartment in cN0 patients with PTC.

Enrolled were 153 cN0 patients with PTC. All underwent total thyroidectomy with central neck dissection and SLNb in the lateral neck compartment, using methylene blue dye as marker. Selective modified radical neck dissection was performed in cases of metastatic SLNs.

Neck LNMs were histologically verified in 40.9% of the cases. Predictive factors for LNM were: males, younger than 45 years, tumors greater than 1cm, capsular and vascular invasion. The central neck compartment of LNM was predictive for lateral LNM in 80.5% of the cases. LNM were confirmed in 24% of SLNs in the lateral neck compartment, which were over 56% predictive of LNM to other dissected lateral LN. SLN identification rate (IR) was 91.8%. Sensitivity, specificity, positive value (PPV) and negative predictive value (NPV) were 85.7, 96.7, 88.3 and 95.9%, respectively. The overall accuracy of the method was 94.3%, with probability of 91.2% (ROC AUC, 95% CI; 84.2-98.3).

The proposed method of SLN biopsy using methylene blue dye is feasible, safe and accurate in the detection of LNM in the lateral neck compartment and may help in the decision to perform selective modified radical neck dissection in cN0 patients with PTC.