Iron-binding proteins in thyroid tumours. An immunocytochemical study.

By immunocytochemistry, the presence of major iron binding proteins (lactoferrin, transferrin and ferritin) was investigated in follicular adenomas (15 cases), Hürthle cell tumours (2 cases) and carcinomas of the thyroid gland (39 cases); normal thyroid tissue was also tested as control. Follicular adenomas showed a negative reaction for all iron-binding antisera, whereas Hürthle cell tumours, follicular and papillary carcinomas exhibited a clear cytoplasmic positivity for lactoferrin and transferrin; ferritin was always absent. Anaplastic carcinomas were unstained with all iron-binding antisera with the exception of giant elements and incorporated follicular structures, which were positive for lactoferrin and transferrin. Medullary carcinomas were constantly unstained. These results are discussed in relation to the increased requirement of iron by neoplastic cells. The authors emphasize the possibility that lactoferrin and transferrin may be utilized in clarifying the differential diagnosis between benign and malignant lesions of follicular cell origin; therefore, these two glycoproteins may be considered useful tools in addition to thyroglobulin.