Papillary Thyroid Carcinoma and Hashimoto's Thyroiditis: New Insights into the Immunological Link

Hashimoto's thyroiditis is the most common autoimmune disease, which is characterized by a cellular immune response with lymphatic infiltration of the thyroid gland mainly by T cells and B cells as well as by a humoral immune response leading to specific antibody production. Papillary thyroid carcinoma, the most common endocrine malignancy, is also characterized by broad immune cell infiltration. In recent years, a growing body of evidence has suggested a close connection between papillary thyroid carcinoma and Hashimoto's thyroiditis. The mechanisms underlying the relationship between Hashimoto's thyroiditis and papillary thyroid carcinoma, however, remain incompletely understood. One hallmark in the understanding of the immunological link between both diseases was the description of identical epitope-specific cytotoxic T cells as clear evidence for a close connection between Hashimoto's thyroiditis und papillary thyroid carcinoma. In this review, we describe the role of Hashimoto's thyroiditis in the development and prognosis of papillary thyroid cancer, the role of thyroid-specific antibodies in the diagnosis and outcome prediction of papillary thyroid carcinoma and the potential implication of this knowledge for cancer immunotherapy in general.