Estrogen-receptor protein in thyroid neoplasms. An immunohistochemical analysis of papillary carcinoma, follicular carcinoma, and follicular adenoma.

Epidemiologic features of well-differentiated thyroid tumors and experimental evidence suggest that female sex hormones may exert effects on this gland and its neoplasms. This possibility was addressed by investigating the expression of estrogen-receptor protein in 80 thyroid neoplasms. Patients with papillary carcinomas, follicular carcinomas, and follicular adenomas were selected from each of the following groups: (1) postpubertal-premenopausal women (who are associated with the most favorable prognosis and greatest incidence of these neoplasms); (2) postmenopausal women; and (3) men of various ages. Sections from formalin-fixed paraffin-embedded tumors were stained with antiestrophilin antibody (clone H222) and the avidin-biotin-peroxidase complex method. In addition, other markers were included to distinguish thyroidal from other estrogen-receptor protein-reactive neoplasms; an anticytokeratin mixture, antithyroglobulin, and anti-gross cystic disease fluid protein-15 were applied in all cases. The expression of estrogen-receptor protein was detected in eight of 10, six of 10, and nine of 10 papillary carcinomas; four of eight, two of seven, and one of five follicular carcinomas; and none of 10, none of 10, and two of 10 follicular adenomas, in groups 1, 2, and 3, respectively. Nuclear staining was regional or multifocal in distribution. Cytokeratin and thyroglobulin were detected in all tumors. In contrast, none displayed anti-gross cystic disease fluid protein-15 immunoreactivity. These results indicate that the estrogen receptor may be detected immunohistochemically in thyroid neoplasms. However, no differences that could account for possible estrogen-related epidemiologic and prognostic variation in such tumors could be ascertained. Other discriminating immunostains, primarily including anti-gross cystic disease fluid protein-15 and thyroglobulin, are effective in distinguishing between thyroidal and extrathyroidal tumors that may express estrogen-receptor protein.