Abstract
Background: Our study investigated the association between chronic lymphocytic thyroiditis (CLT) and thyroid cancer (TC). Methods: A retrospective review of 1670 patients who underwent thyroid surgery between October 2022 to February 2025 was performed. The clinicopathological characteristics of patients with TC and CLT were collected. CLT was diagnosed histopathologically. Results: Patients with a positive CLT result (60.39%) compared to a negative CLT result (34.12%) had more frequently TC (p < 0.001), predominantly PTC. In univariate analysis, patients with malignancy + CLT-positive compared to malignancy + CLT-negative were found to be younger in age (p < 0.001), female gender (p < 0.001), smaller tumours focus (p = 0. 013), smaller mass of thyroid removed (p < 0.001) and more often Bethesda category V and VI (p = 0.019), true positive fine needle aspiration biopsy (FNAB) for PTC (p = 0.009), and microcarcinoma (p = 0.021). There were no differences in multifocality, the presence of LNM, or the number of LNMs. The location of metastases at neck lymph nodes was at the borderline of significance (p = 0.065). In multivariate analysis, after accounting for Bethesda and age, CLT+ was found to increase the risk of TC by 73% (OR = 1.73; 95%CI, 1.15-2.29), while the risk of PTC increased more than 2-fold (OR = 2.12; 95% CI, 1.45-3.11). CLT had no statistically significant effect on the presence of LNM. Conclusions: We found that CLT is a risk factor for TC. One should be vigilant concerning the coexistence of these two diseases. We suggest that total thyroidectomy should be considered in patients referred for thyroid nodules and suspected CLT. However, this issue requires further research.