Immunohistochemical staining for thyroglobulin in poorly differentiated carcinoma of the thyroid.

Paraffin sections of 14 specimens of poorly differentiated tumours of the thyroid were stained for thyroglobulin using polyclonal antibodies and a streptavidin-biotin peroxidase staining system. The better differentiated areas showed positive staining, while the poorly differentiated areas gave weakly positive or negative staining. Thyroglobulin staining is useful in attributing a thyroid epithelial cell origin to a tumour, but negative staining does not exclude this.