Immunohistochemical markers of thyroid tumors: significance and diagnostic applications.

Immunohistochemical markers of thyroid tumors can be divided into two major categories: those related to the cell types and those related to the type of pathology. The most important markers in the first category are thyroglobulin and TTF-1 for follicular cells, and calcitonin, CEA, and chromogranin for C cells. Markers in the second category are primarily directed at papillary carcinoma and include cytokeratin 19, high-molecular weight keratin (identifiable with antibody 34betaE12), S-100 protein, HBME-1, galectin 3, and p27kip1. At the practical level, cell type-related markers are much more useful than disease-related markers. Markers said to be of prognostic value in medullary carcinomas are calcitonin, bcl-2, and N-myc.