Immunocytochemistry of the thyroid in surgical and cytologic specimens.

The value of immunocytochemistry in thyroid disease was evaluated in histologic and cytologic material derived from papillary carcinoma (25 cases), follicular carcinoma (nine cases), follicular adenoma (nine cases), Hürthle cell tumor (three cases), medullary carcinoma (two cases), nodular goiter (nine cases), and Hashimoto's thyroiditis (two cases). Thyroglobulin was positive in the follicular cells and/or colloid of all lesions (except medullary carcinoma) and two papillary carcinomas. Vimentin was positive in papillary carcinoma (17 of 25), follicular carcinoma (four of nine), follicular adenoma (four of nine), and nodular goiter (two of nine). Vimentin positivity, which was restricted to follicular cells, was strongest in those cells undergoing oncocytic transformation. Three markers of glandular/acinar secretory differentiation (lactoferrin, lactalbumin, and secretory component) were uniformly negative even in well differentiated follicular structures. In medullary carcinoma, both calcitonin and carcinoembryonic antigen were strongly positive in the parafollicular cells. The antibody panel can definitely identify histogenesis from the thyroid but is of little value in tumor classification. In histologic and cytologic preparations, vimentin positivity does not exclude thyroid follicular cell origin. The method can be successfully applied to richly cellular needle aspirates. This is best achieved with assisted needle aspirations when cellularity is ascertained by on-site microscopic examination of multiple passes.