EXPRESSION OF SIMPLE MUCIN-TYPE ANTIGENS AND LEWIS TYPE-1 AND TYPE-2 CHAIN ANTIGENS IN THE THYROID-GLAND - AN IMMUNOHISTOCHEMICAL STUDY OF NORMAL THYROID TISSUES, BENIGN LESIONS, AND MALIGNANT-TUMORS

In order to characterize the pattern of expression of carbohydrate str uctures in several types of thyroid tissues and to evaluate the putati ve usefulness of the detection of such antigens in diagnostic surgical pathology, we undertook the immunohistochemical study of simple mucin type antigens (T, Tn, and sialyl Tn), Lewis type I antigens (Lewis a, sialyl Lewis a, and Lewis b), and Lewis type 2 related antigens (prec ursor type 2, H type 2, Lewis x, sialyl Lewis x, and Lewis y) in thyro id samples obtained from 65 patients. The material consisted on paraff in sections of normal thyroid (n = 43), benign lesions (13 goiters/hyp erplastic lesions and 15 adenomas), and malignant tumors (12 follicula r carcinomas and 27 papillary carcinomas, 5 of which had lymph node me tastases) of the thyroid follicular epithelium. Tn, T, and precursor t ype 2 antigens were the only antigens that were detected-and very rare ly-in normal thyroid. Benign lesions were similar to normal thyroid de spite displaying a higher prevalence of immunoreactivity for several a ntigens of the three groups. Thyroid carcinomas presented a significan tly higher level of expression of all types of simple mucin, Lewis typ e 1, and Lewis type 2 antigens than the normal thyroid and benign lesi ons. The expression of sialyl Tn was restricted to malignant tumors, a nd the expression of sialyl Lewis x was closely associated, though not exclusively, to papillary carcinomas. The immunoreactivity was strong er and the number of positive cases was higher in papillary than in fo llicular carcinomas. No differences were found between primary tumors and the respective metastases. The existence of distinct patterns of e xpression of carbohydrate antigens in different types of thyroid lesio ns points to the usefulness of the detection of some of these antigens in thyroid surgical pathology. The putative role of such antigens in the peculiar metastatic properties of thyroid carcinomas remains unset tled.