BACKGROUND

Although occult lymph node metastasis to the lateral neck compartment is common in papillary thyroid carcinoma, the incidence and patterns of lateral neck node metastasis in papillary carcinoma are not known. We hypothesized that sentinel lymph node biopsy (SLNB) with radioisotope in the detection of occult lateral neck node metastasis would be useful in characterizing metastasis in papillary carcinoma.

METHODS

Ninety-four patients with papillary thyroid carcinoma were included from June 2009 to March 2010 for lateral neck SLNB. Preoperative lymphoscintigraphy was obtained after intratumoral injection of a (99m)Tc-tin colloid under ultrasound guidance. Total thyroidectomy or lobectomy preceded SLN detection to avoid radioactivity interference with the primary tumor, after which SLNB was performed in the lateral neck nodes. In the cases where metastasis was detected in SLNs upon frozen biopsy, an immediate modified radical neck node dissection was performed.

RESULTS

A total of 174 SLNs were identified in 60 patients (63.8%). The identification rate of the SLNs with isotope increased with time. Sentinel lymph node metastasis was found in 19 patients (31.7%). This clinically occult metastasis was only related to the total number of metastatic LNs in the central compartment. Patient age, gender, tumor size, location, extent of tumor invasion, multiplicity, and presence of thyroiditis were not related to metastasis in the lateral compartment. Detection of lateral neck SLNs upon biopsy with radioisotope was also feasible in level II and contralateral neck.

CONCLUSIONS

Sentinel lymph node biopsy is a useful method for evaluating the occult lateral neck lymph node status in patients with papillary thyroid carcinoma, especially in the cases of central neck node metastasis.