[Cytokeratin expression of benign and malignant epithelial thyroid gland tumors. An immunohistologic study of 154 neoplasms using 8 different monoclonal cytokeratin antibodies].

Using 8 different monoclonal antibodies, immunohistology was performed on 36 follicular adenomas and on 28 follicular, 34 papillary, 27 medullary and 29 anaplastic carcinomas of the thyroid. The panel of antibodies was directed against broad-spectrum cytokeratins (pan-CK, antibody lu-5), against basic and acid high-molecular-weight CK of types #1, 5, 10 and 14, against basic (#5 and 6) and acid high-molecular-weight CK (#13) and against basic (#7 and #8) and acid low-molecular-weight CK (#19 and #20). With the exception of a large number of anaplastic carcinomas, nearly all other tumours exhibited strong immunoreactivity with antibodies against pan-CK, CK 8 and CK 19. CK 20 expression was exclusively shown for 2 medullary carcinomas. Reactivity for high-molecular-weight CK could only, each time focally, be demonstrated for 14 papillary and 2 follicular carcinomas and for 2 anaplastic carcinomas with partial squamous differentiation. Thirteen anaplastic carcinomas were not decorated by any of the CK antibodies applied. CK 7 staining exceeding the staining of individual cells was observed in 26 papillary cancers. In contrast, such a finding could only be obtained with each one follicular adenoma, medullary carcinoma and anaplastic carcinoma and with 5 follicular carcinomas. These results confirm earlier studies in that CK 20 expression among thyroid tumours is restricted to the neuroendocrine medullary carcinomas and that in a larger percentage of anaplastic thyroid carcinomas an epithelial phenotype can not be demonstrated even upon using broad-spectrum CK antibodies. New is the finding that there exist considerable differences between papillary carcinomas and all other non-papillary thyroid tumours regarding CK 7 expression. This result might be of differential diagnostic value for the distinction of follicular and papillary thyroid neoplasias which sometimes have an overlapping histological pattern.