Central lymph node metastasis in papillary thyroid microcarcinoma can be stratified according to the number, the size of metastatic foci, and the presence of desmoplasia.

Background Lymph node (LN) metastasis is common in papillary thyroid microcarcinoma (PTMC). The aim of this study was to investigate the impact of LN metastasis and its risk stratification on PTMC recurrence. Methods We retrospectively reviewed the data of 336 patients with PTMC who underwent surgery from 2005 to 2006 at a single institution. LN metastasis was stratified according to the number of metastatic LNs, the ratio of metastatic to removed LNs, the size of metastatic foci in LNs, and the presence of extranodal extension and desmoplasia. Results Of the 336 patients, 93 (28%) had LN metastasis. During the follow-up of 5.3 years, 16 (4.8%) experienced locoregional recurrence. Among several clinicopathologic factors, LN metastasis was the most important risk factor for recurrence ( P  = .02). Lateral LN metastasis was correlated with recurrence-free survival ( P P  = .20). When central LN metastasis was stratified, a high number of metastatic LNs (≥3), larger metastatic foci (≥0.2 cm), and the presence of desmoplasia were associated with recurrence-free survival ( P Conclusion The prognostic significance of central LN metastasis can differ according to the number of metastatic LNs, the size of metastatic foci, and the presence of desmoplasia. Patients with a high number of metastatic LNs, larger metastatic foci, and presence of desmoplasia in LNs should be treated aggressively and supervised carefully for PTMC recurrence.