Immunohistochemical demonstration of lactoferrin in follicular adenomas and thyroid carcinomas

By immunohistochemistry, the presence of lactoferrin was investigated in follicular adenomas (10 cases) and carcinomas of the thyroid gland (23 cases). Normal thyroid tissue was also tested as control. Follicular adenomas showed a consistent negativity, whereas follicular and papillary carcinomas exhibited various degrees of positivity for lactoferrin. Incorporated organoid structures observed in anaplastic carcinomas were strongly stained; the spindle cell parts of these cancers were always negative for this iron-binding protein. Medullary carcinomas were also unstained. These findings are discussed in relation to the distribution pattern of thyroglobulin. The authors emphasize the possibility that lactoferrin may be useful in clarifying some diagnostic problems in neoplastic thyroid pathology.