Is lymphocytic thyroiditis a unique type or merely a type of Hashimoto's thyroiditis?

Abstract

Aim: Objective of the study was to clarify the role of apoptosis in the pathogenesis of lymphocytic thyroiditis (LT) and the existence of difference between Hashimoto's thyroiditis (HT) and LT. Methods: We evaluated levels of antithyroglobulin and antithyroperoxidase antibodies, the apoptosis by in situ Cell Death Detection-TUNEL and the expression of Bcl2 and Bax by immunohistochemistry in thyroid tissues from 16 patient with HT, 10 with LT and 10 with euthyroid goiter-EG (control group). Results: It was found that apoptosis of thyrocytes in HT (mean 3.05%, SD 1.29%) and LT (mean 2.70%, SD 1.17%) was statistically significantly higher than EG (mean 0.56%, SD 0.23%), but the difference in the percentage of thyrocytes between HT and LT was not statistically significant. In HT the percentage of apoptotic infiltrating lymphocytes (mean 0.59%, SD 0.23%) was smaller than in EG (mean 2.26%, SD 1.42%), but it showed no significant difference in comparison to LT. The expression of Bax in infiltrating lymphocytes in HT (mean 0.72%, SD 0.34%) was statistically significantly higher than LT (mean 0.11%, SD 0.06%). The level of thyroglobulin was lower in HT compared to LT (P<0.01) and compared to EG (P<0.01). The level of antithyroglobulin/antithyroperoxidase antibodies was higher in HT compared to LT (P<0.01) and compared to EG (P<0.01). There was no statistically significant difference in the level of thyroglobulin and level of antibodies between LT and EG. Conclusion: These results suppose that apoptosis represents one of significant mechanisms in the pathogenesis of both HT and LT and that LT probably differs from HT.