The Number of Lymph Nodes and Relationship with Presence of Thyroiditis and Thymic Tissue in the Central Neck Dissection Materials for Thyroid Papillary Carcinoma: Pathologic Analysis

Abstract

Background: Central lymph node dissection (CLND) for papillary thyroid carcinoma (PTC) allows correct pathologic staging of lymph nodes and planning of postoperative management. The purpose of this study was to determine the number of the lymph nodes in the CLND and the relationship to presence of chronic lymphocytic thyroiditis (CLT) and thymic tissue (TT). Methods: Total thyroidectomy and CLND materials from 153 patients with PTC were included in this study. Two histopathologic features (presence of CLT and TT) were evaluated for their value in adequacy of CLND. Results: Histopathologic examination revealed CLT and TT in CLND materials in 70 (46%) and 63 (41%) patients, respectively. Total number of lymph nodes in CLND materials was significantly higher in CLT (+) and TT (+) groups (p < 0.001), independently. LN metastases in central compartment were found in 40% of patients (n = 61). Of these, 30 patients had underlying CLT. The metastatic LN ratio (metastatic LN/total LN) was significantly lower in CLT (+) group, comparing to CLT (-) group (16.8% ± 12.2% vs 46.4% ± 27.5%; p < 0.001). Conclusions: Our study demonstrates that presence of CLT in thyroid gland has been associated with higher number of central lymph nodes mainly due to increased number of benign hyperplastic lymph nodes. It may be possible to conclude that upper limit of lymph nodes for satisfactory CLND would be higher to correctly evaluate central lymph node status in existing staging systems if specimens have CLT. Results of this study also show that the presence of TT in surgical materials may represent the adequacy of CLND.