Immunohistochemical study of ceruloplasmin, lactoferrin and secretory component expression in neoplastic and non-neoplastic thyroid gland diseases.

The expression of lactoferrin (LF), ceruloplasmin (CP) and secretory component (SC) in various thyroid diseases was investigated using an immunohistochemical method. LF is an iron-binding protein overexpressed in certain human adenocarcinomas. CP is implicated in carcinogenesis and SC is part of the local immune defense system. Sections of 15 follicular adenomas, 5 follicular carcinomas (FC), 16 papillary carcinomas (PC), 15 goitres and 2 cases of lymphocytic thyroiditis were re-examined and investigated immunohistologically by a streptavidin-biotin method. A positive immunostain reaction for CP and LF was observed in all cases of PC and FC. A positive immunostain reaction for SC was observed in 13/16 cases of PC and 4/5 cases of FC. A negative immunostain reaction for CP, LF and SC was observed in medullary cancers, in follicular adenomas and in the cases with goitre. We conclude that the immunostain expression of LF, CP and SC is a valuable diagnostic aid in the differential diagnosis between benign and malignant thyroid tumors. The expression of SC indicates the presence of a local immunodefensive system.