CYTOKERATIN EXPRESSION OF BENIGN AND MALI GNANT EPITHELIAL THYROID-TUMORS - AN IMMUNOHISTOCHEMICAL STUDY OF 154 NEOPLASIAS USING 8 DIFFERENT MONOCLONAL ANTI-CYTOKERATIN ANTIBODIES

Using 8 different monoclonal antibodies, immunohistology was performed on 36 follicular adenomas and on 28 follicular, 34 papillary, 27 medu llary and 29 anaplastic carcinomas of the thyroid. The panel of antibo dies was directed against broad-spectrum cytokeratins (gan CK, antibod y 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 C K (#19 and #20). With the exception of a large number of anaplastic ca rcinomas, nearly all other tumours exhibited strong immunoreactivity w ith antibodies against pan-CK, CK 8 and CK 19. CK 20 expression was ex clusively shown for 2 medullary carcinomas. Reactivity for high-molecu lar-weight CK could only, each time focally be demonstrated for 14 pap illary and 2 follicular carcinomas and for 2 anaplastic carcinomas wit h partial squamous differentiation. Thirteen anaplastic carcinomas wer e not decorated by any of the CK antibodies applied. CK 7 staining exc eeding the staining of individual cells was observed in 26 papillary c ancers. In contrast, such a finding could only be obtained with each o ne follicular adenoma, medullary carcinoma and anaplastic carcinoma an d with 5 follicular carcinomas. These results confirm earlier studies in that CK 20 expression among thyroid tumours is restricted to the ne uroendocrine medullary carcinomas and that in a larger percentage of a naplastic thyroid carcinomas an epithelial phenotype can not be demons trated even upon using broad-spectrum CK antibodies. New is the findin g that there exist considerable differences between papillary carcinom as and all other non-papillary thyroid tumours regarding CK 7 expressi on. This result might be of differential diagnostic value for the dist inction of follicular and papillary thyroid neoplasias which sometimes have an overlapping histological pattern.