Sentinel lymph node biopsy as guidance for central neck dissection in patients with papillary thyroid carcinoma

Occult lymph node metastasis of papillary thyroid carcinoma (PTC) can be detected by sentinel lymph node (SLN) biopsy, but studies in larger patient cohorts undergoing complete central neck dissection may be required to assess the diagnostic accuracy of SLN. Therefore, the authors prospectively assessed the usefulness of SLN biopsy for the detection of central lymph node metastasis in patients with differentiated PTC who had no suspicious cervical lymphadenopathy.

After peritumoral injection of methylene blue, SLN biopsy was performed in 50 patients with newly diagnosed PTC who had no palpable or ultrasound (US)-detected lymph node involvement. After SLN biopsy, all patients underwent total thyroidectomy and central neck dissection. The diagnostic accuracy of intraoperative SLN sampling was calculated by comparison with the final pathologic diagnosis.

SLNs were identified in 46 of 50 patients (92%); of these, 14 SLNs were positive and 32 SLNs were negative on intraoperative frozen sections. One patient had a positive SLN in the jugular region and subsequently underwent modified radical neck dissection. Final pathologic examination revealed that 18 patients (36%), including 4 who had negative SLNs, had central lymph node metastasis. Thus, the sensitivity, specificity, accuracy, and positive and negative predictive values of SLN biopsy were 77.8%, 100%, 92%, 100%, and 88.9%, respectively. Temporary and permanent hypocalcemia developed in 19 patients and 1 patient, respectively. There were no direct complications of SLN sampling.

SLN biopsy in patients with PTC without gross clinical or US lymph node involvement was able to detect occult metastasis with high accuracy and may have the potential to select patients who require central neck dissection.