[Immunohistochemical demonstration of cytokeratin in thyroid neoplasms and its clinical implications].

Formalin fixed paraffin sections of previously resected surgical specimens and ethanol fixed stamped samples of newly obtained specimens from patients with thyroid neoplastic lesions were investigated for the presence of cytokeratin by the help of avidin-biotin peroxidase complex (ABC) method using anticytokeratin monoclonal antibody PKK-1. The result showed that PKK-1 reacted only to a large cell variant of anaplastic carcinoma of the thyroid and not to a small cell type. Therefore this method appears not to be useful for differentiation between small cell carcinoma and lymphoma. The differentiation between papillary carcinoma and follicularly growing tumor was possible by this method because the former reacted to PKK-1 at a high rate, whereas most of the latter were negative to it. Freshly prepared stamped samples showed a better reaction to the monoclonal antibody, and thus this technique appears to be applicable to an aspiration biopsy cytology.