Lateral neck metastases in the ipsilateral and contralateral compartments of papillary thyroid carcinoma located in one lobe

Background: Papillary thyroid carcinoma (PTC) frequently involves lymph nodes in the lateral compartment, but PTC located in one lobe rarely metastasizes to bilateral lateral nodes. This study was designed to evaluate the clinicopathological features of patients with PTC limited to one lobe but with bilateral lateral neck metastasis (LNM). Methods: Between January 2009 and December 2013, 698 patients with unilateral PTC with LNM were analysed. Of these patients, 651 had unilateral LNM (ULNM) and 47 had bilateral LNM (BLNM). The clinicopathological characteristics of the two groups were analysed. Results: There were no significant between-group differences in age, extrathyroidal extension, multifocality in one lobe, thyroiditis or psammomatous calcification. Male sex (51.1% versus 29.8%; P = 0.002), central compartment metastasis (91.5% versus 78.6%, P = 0.035), aggressive subtype of PTC (23.4% versus 8.8%; P = 0.001) and Delphian node metastasis (36.2% versus 18.1% versus 36.2%, P = 0.002) were significantly more frequent, and mean primary tumour size (1.79 ± 1.12 cm versus 1.34 ± 0.83 cm, P = 0.010) significantly larger in the BLNM than in the ULNM group. Conclusions: Although few patients with PTC located in one lobe have BLNM, the contralateral lateral compartment should be carefully evaluated for BLNM in males and in patients with a primary tumour size >2 cm, aggressive subtype of PTC, central node metastasis and Delphian node metastasis.