Differences in tumor cell proliferation, HLA DR expression and lymphocytic infiltration in various types of thyroid carcinoma.

The proliferative activity of various thyroid carcinoma forms (papillary, follicular, medullary, anaplastic) was investigated using two second generation antibodies against Ki-67 that can be used on paraffin-embedded sections. Poorly-differentiated carcinomas had a higher proliferation than well-differentiated forms. Papillary carcinoma stained significantly more often with either antibody than follicular carcinoma. A solid growth pattern correlated with high Ki-67 expression while an increase in follicular elements and a high amount of psammoma bodies coincided with lower proliferation.HLA class II expression and infiltrating lymphocytes are prerequisites for an immune defense against cancer. In this study, HLA DR was increased in poorly-differentiated carcinomas, especially in the anaplastic type. The increase in HLA DR was correlated with Ki-67 positivity. On tumor-infiltrating lymphocytes, HLA DR was well expressed in papillary carcinoma and relatively poorly expressed in follicular carcinoma, but there was no significant correlation with carcinoma type or morphological parameters. CD 45 R0, which might recognize memory cells, was found mostly in anaplastic and papillary carcinomas, and correlated well with HLA DR expression. These findings imply that an active but variable immune response is present in thyroid carcinoma.