Extent of lateral neck dissection for papillary thyroid microcarcinomas.

BACKGROUND: Papillary thyroid microcarcinomas (PTMCs) often demonstrate lateral lymph node (LN) metastasis. The purpose of this study was to assess whether the size of primary tumor should be considered in deciding lateral neck dissection extent.

METHODS: We conducted a retrospective comparison of patients with PTMC and papillary thyroid carcinoma (PTC) larger than 1 cm who received lateral LN dissection from 2009 to 2015.

RESULTS: PTMC group had more frequent metachronous metastasis, multifocality, less involvement of lower third thyroid, lower metastatic central LN counts and ratio, and lower metastatic total LN ratio. The two groups showed no difference in lateral LN metastatic pattern. Male and lymphovascular invasion were more often found in PTMCs with synchronous lateral LN metastatic events than metachronous presentations.

CONCLUSIONS: Relying on the size of the tumor to determine lateral neck dissection extent could be unreliable, because there is no observed difference in lateral neck metastatic count and pattern between PTC and PTMCs.