Lymphocytic infiltration in juvenile thyroid carcinoma.

In this study, the significance of lymphocytic infiltration in juvenile thyroid carcinoma is clarified. We examined nine patients younger than 20 years of age. Histopathologically, there was good correlation between lymphocytic infiltration and the development and spread of carcinoma. It is believed that lymphocytic infiltration around the tumor is an immunologic reaction induced by antigens from the carcinoma itself, and also that the reaction may progress according to tumor development. Immunocytochemically, we determined what type of inflammatory cells infiltrated the thyroid and demonstrated HLA-DR expression in the cancer cells. These findings are similar to autoimmune thyroiditis in which antibody-dependent cellular cytotoxicity (ADCC) works as a main immunomechanism.