Central Cervical Nodal Metastasis from Papillary Thyroid Microcarcinoma: Pattern and Factors Predictive of Nodal Metastasis

Background  Although several factors are thought to predict the occurrence of lymph node metastases from papillary thyroid microcarcinoma (PTMC), the pattern of nodal metastasis has been rarely studied. We evaluated the pattern and factors predictive of central cervical metastasis from PTMC. Methods  Seventy-two patients with PTMC underwent total thyroidectomy and central neck dissection, including three who underwent therapeutic modified radical neck dissection. Lymph node involvement was analyzed by neck subsite, and clinicopathologic variables predictive of nodal metastasis were determined. Results  Central and lateral nodal metastases were found in 29 (40.3%) and 3 (4.2%) patients, respectively, and ipsilateral paratracheal, pretracheal, superior mediastinal, and contralateral paratracheal lymph node metastases in 27 (37.5%), 8 (11.1%), 4 (5.6%), and 1 (1.4%), respectively. Sex, age, tumor size, multifocality, bilaterality, extracapsular invasion, lymphovascular invasion, and MACIS (metastases, age, completeness of resection, invasion, size) for central node metastasis were not predictive of metastasis (P > .1). Temporary and permanent hypocalcemia was observed in 17 (23.6%) and 1 (1.4%) patients, respectively, and transient vocal fold paralysis in 1 (1.4%). Conclusion  Despite the absence of palpable neck nodes, PTMC is associated with a high rate of central lymph node metastasis to ipsilateral and pretracheal subsites. No clinicopathologic factor predicted nodal metastasis. In patients with PTMC involving one lobe and positive nodes, neck dissection may exclude the contralateral side.