The influence of chronic lymphocytic thyroiditis (CLT) on clinicopathological features and behavior of differentiated thyroid carcinoma (DTC) is still debated. In the present study, we aimed to evaluate the prognosis of DTC on the presence of CLT. A total of 649 total thyroidectomized patients (379 female, 270 male) with DTC, who had follow-up data for at least 36 months were included. Clinical, histopathological data, preoperative thyroid peroxidase antibody (TPO-ab), thyroglobulin antibody (Tg-ab), thyroid-stimulating hormone (TSH) levels, and presence of recurrent/persistent disease (R/PD) were evaluated retrospectively. Presence of CLT was defined by histopathology. Frequency of CLT was 32% (n = 208) among DTC patients. Mean tumor size (maximal diameter) was smaller in CLT group when compared to non-CLTs (p = 0.006). Capsular invasion, vascular invasion, tumor stage, risk groups, and R/PD were negatively associated with CLT (p < 0.01, p = 0.04, p = 0.03, p = 0.02, p < 0.01, respectively). Extrathyroidal extension was more frequent in non-CLT group when compared CLT (p = 0.052). Preoperative TSH level was positively associated with lymph node metastasis (LNM) and higher in patients with lateral LNM when compared to central LNM (p < 0.01). Central LNM, lateral LNM, stage 4 tumor, and intermediate- and high-risk tumor groups increased the risk of R/PH, 2.5-, 2.9-, 12.7-, 2.3-, and 4.2-fold, respectively. Presence of CLT was independently related with favorable outcomes, as the risk of R/PD was decreased by 0.49-fold. In conclusion, coexistence of CLT was negatively associated with tumor size, capsular invasion, vascular invasion, and tumor stage in DTC. Risk of R/PD was decreased by approximately half in patients with CLT.
Keywords: Chronic lymphocytic thyroiditis; Differentiated thyroid cancer; Lymph node metastasis; Prognosis.