Papillary Thyroid Carcinoma Located in the Isthmus or Upper Third is Associated with Delphian Lymph Node Metastasis

Delphian lymph node (DLN) metastasis is a recognized indicator of further lymph node involvement in papillary thyroid carcinoma (PTC). The aim of this study was to evaluate the clinicopathological significance of and risk factors for DLN metastasis. The medical records of 1,436 patients who underwent primary thyroidectomy for classical PTC with a tumor size of 2 cm or less were reviewed. Of these, 370 patients from whom the DLN was harvested were enrolled. Metastasis in DLN was present in 46 patients and absent in 324 patients. Clinicopathological features were compared according to DLN metastasis. In univariate analysis, DLN metastasis was associated with suspected lymph node metastasis on preoperative ultrasonography, tumor location in the isthmus or upper third of the thyroid, larger tumor size, extrathyroid extension, lymphovascular invasion, and further lymph node metastasis. Multivariable analysis revealed that DLN metastasis was associated with tumor location in the isthmus or upper third of the thyroid (odds ratio [OR] = 2.420; 95 % confidence interval [CI] 1.193–4.910) and further lymph node metastasis (OR = 4.746; 95 % CI 2.065–10.908). DLN metastasis in PTC is associated with tumor location in the isthmus or upper third of the thyroid and unfavorable clinicopathological characteristics. Careful consideration and patient management are warranted when preoperative ultrasonography indicates that the tumor is located in the isthmus or upper third of the thyroid.