Predictors of cervical lymphatic spread in papillary thyroid microcarcinoma: clinical and pathological determinants

This study aimed to identify clinicopathological predictors of central lymph node metastasis (CLNM) in patients with clinically node-negative (cN0) papillary thyroid microcarcinoma (PTMC), to assess the implications for selective prophylactic central lymph node dissection, and to determine factors associated with lateral lymph node metastasis (LLNM). This retrospective cohort study included 360 patients with postoperative pathological confirmation of PTMC treated between June 2024 and March 2026. Of these, 335 had cN0 disease on preoperative imaging and were included in the CLNM analysis; 25 had preoperatively suspected and cytologically confirmed LLNM. Age, sex, maximal tumor diameter, thyroid capsular invasion, Hashimoto's thyroiditis, extrathyroidal extension, vascular invasion, multifocality, and distant metastasis were evaluated. Among the 335 patients with cN0 PTMC, univariable analysis showed that male sex, age less than 45 years, tumor diameter greater than 0.55 cm, multifocality, vascular invasion, thyroid capsular invasion, and extrathyroidal extension were associated with CLNM. Multivariable logistic regression identified male sex, age less than 45 years, tumor diameter greater than 0.55 cm, multifocality, and thyroid capsular invasion as independent predictors of CLNM (all P < 0.05). In the full cohort, male sex, tumor diameter greater than 0.55 cm, vascular invasion, thyroid capsular invasion, extrathyroidal extension, and distant metastasis were associated with LLNM in univariable analyses. Male sex [odds ratio (OR) = 2.512, 95% confidence interval (CI): 1.268-4.975, P = 0.008), thyroid capsular invasion (OR = 3.021, 95% CI: 1.472-6.202, P = 0.003), and extrathyroidal extension (OR = 2.678, 95% CI 1.183-6.062, P = 0.018) remained independent predictors of LLNM. Distinct clinicopathological profiles were associated with central and lateral nodal spread in PTMC. These findings may improve perioperative risk stratification and support selective consideration of prophylactic central lymph node dissection in cN0 patients with high-risk features, while balancing the potential benefits against procedure-related morbidity.