Phenotypic changes of the thyrocyte membrane in papillary thyroid carcinoma. A three-dimensional study.

Aim of the study was to assess the presence of structural changes in the complex carbohydrate chains of thyroid epithelia undergoing neoplastic transformation. We investigated thyroid cells from neoplastic lesions using a panel of lectins with specific affinity for distinct carbohydrate residues. Sixty samples of thyroid tissue, including normal, hyperplastic and neoplastic lesions were obtained from surgical specimens and blindly evaluated with lectin stains. Confocal microscopy was used to obtain three-dimensional (3-D) images of the samples with a positive reaction. Wheat germ agglutinin (WGA) was consistently positive on the apical membrane of papillary thyroid carcinomas (PTC), was weakly expressed in follicular carcinomas (FC) and resulted negative in normal thyrocytes and in benign conditions. The 3-D microscopy model showed that the WGA staining pattern in light microscopy corresponds to a continuous layer on the luminal surface of both papillary and tubular structures of PTC cells. The other lectins under evaluation did not provide any significant result. In conclusion, in PTC the apical border of thyrocytes showed a strong, specific and consistent staining with WGA. These findings may be related to a modified interaction of thyroglobulin molecule with thyroid cell membrane and with the expression of molecules that are involved in the process of tumorigenesis and tumor progression.