Immunohistochemical demonstration of ceruloplasmin in follicular adenomas and thyroid carcinomas

The presence of ceruloplasmin in follicular adenomas (15 cases) and thyroid carcinomas (39) and two Hürthle cell tumours was investigated by immunohistochemical methods. Follicular adenomas were all negative whereas Hürthle cell tumours, follicular and papillary carcinomas exhibited various degrees of cytoplasmic positivity for ceruloplasmin. Highly atypical multinucleated cells and incorporated follicular structures observed in anaplastic carcinomas were positively stained; the spindle cell variety of these cancers was always negative for ceruloplasmin. Medullary carcinomas and normal thyroid tissue were constantly unstained. The distribution pattern of ceruloplasmin is the same as that of lactoferrin, a marker recently proposed for the differential diagnosis between follicular adenomas and thyroid carcinomas; these two glycoproteins are structurally related.