Can intraoperative frozen section influence the extension of central neck dissection in cN0 papillary thyroid carcinoma?

Ipsilateral central compartment node dissection has been proposed to reduce the morbidity of prophylactic bilateral central compartment node dissection in papillary thyroid carcinoma (PTC), but it carries the risk of contralateral metastases being overlooked in approximately 25 % of patients. We aimed to verify if frozen section examination (FSE) can identify patients who could benefit from bilateral central compartment node dissection. All the consenting patients with clinically unifocal PTC, without any preoperative evidence of lymph node involvement, observed between September 2010 and September 2011 underwent total thyroidectomy plus bilateral central compartment node dissection. Ipsilateral central compartment nodes were sent for FSE. Forty-eight patients were included. Mean number of removed nodes was 13.2 +/- 6.8. Final histology showed lymph node metastases in 21 patients: ipsilateral in 15, bilateral in 6. FSE accurately predicted lymph node status in 43 patients (27 node negative, 16 node positive). Five node metastases were not detected at FSE: three were micrometastases (a parts per thousand currency sign2 mm). Sensitivity, specificity and overall accuracy of FSE in definition of N status status were 80.7, 100, and 90 %, respectively. FSE is accurate in predicting node metastases in clinically unifocal node negative PTC and can be useful in determining the extension of central compartment node dissection. False-negative results are reported mainly in case of micrometastases, which usually have limited clinical implications.