[Expression of galectin-3 in thyroid gland and follicular cell tumors of the thyroid. A critical study of its possible role in preoperative differential diagnosis].

Galectin-3 belongs to a group of endogenous lectins with an affinity to glycoconjugates containing beta-galactoside residues. It has been detected in numerous tissues and studied in connection with tumor growth, dedifferentiation, and metastasis. Only few studies have dealt with galectin-3 detection in tumors of the thyroid gland and with its possible role for differential diagnosis. We studied 118 cases of thyroid gland tumors with a monoclonal antibody against galectin-3; we compared the preparations by a semiquantitative score to determine differences in expression. Normal thyroid gland tissue, goiter tissue, and tissue with functional enhancement were largely negative for galectin-3. Adenomas with a typical cytological pattern were predominantly negative, but a focal positive reaction in single cells and cell groups or follicles was possible. Almost all papillary carcinomas showed a distinct galectin-3 expression. While findings in follicular carcinomas and oxyphilic adenomas and carcinomas were very uneven, with both positive and negative tumors, the galectin-3 reaction can be helpful in recognizing follicular variants of the papillary carcinoma. Investigation of the biological significance of tumors should always be cautious and consider known histological criteria for malignancy.