Immunohistochemical analysis of thyroglobulin and keratin in benign and malignant thyroid tumours.

56 thyroid gland tumours and non neoplastic alterations were studied for keratin and thyroglobulin staining, using the indirect immunoperoxidase method on serial formalin fixed paraffin embedded sections. Papillary carcinomas showed a strong reaction with anti-keratin serum but a weak reaction with anti-thyroglobulin serum. Follicular adenomas and carcinomas showed virtually no reaction for keratin but a strong reaction for thyroglobulin. Undifferentiated and medullary carcinomas did not react with either antiserum, except for single cells in two undifferentiated carcinomas which reacted with anti-keratin serum. In nodular goiters, hyperplastic follicles showed little or no reaction with anti-keratin serum and strong reaction with anti-thyroglobulin serum. It is suggested that this virtually type-specific staining for keratin or thyroglobulin may be related to different degrees of cellular differentiation and organelle content in the tumour cells.