[Thyroid nodule: morphostructural diagnosis and molecular substrate]

This survey offers an up-to-date overview of the latest findings relevant to molecular mechanisms of thyroid carcinogenesis, also based on our considerable experience with regard to the paradigmatic and atypical cytohistogenetic alterations specific to the various forms of thyroid proliferation, both malignant and benign. We have, moreover, illustrated the most recent applicative interchanges of the biomolecular methodologies relating to the diagnostic protocols to be carried out, in order to characterize the tumorous lesions. Particular emphasis has been focused on the role played by the molecular diagnosis of those lesions which cannot be pinpointed using traditional cytologic analysis and which are called "follicular proliferations". Among the innovative, diagnostic methodologies centered on the applications of the latest biomolecular findings relevant to thyroid oncogenesis, the immunocytochemical method, involving galectina-3 staining, plays a pivotal, diagnostic role as a marker of malignancy. In our experience this modern immunohistochemical methodology provides an extremely selective diagnostic support, possessing considerable sensitivity. This molecular approach is able to solve the diagnostic issue raised by the uncertainty of the neutral cytologic diagnostic report which demands a precise biomolecular specification of the nature of the nodules, cytologically set within the framework of the lesions described as aspecific, follicular structure anomalies. Furthermore, the new findings relating to the molecular mechanisms involved in the formation and neoplastic progression of the proliferous thyroid anomalies offer useful elements for the development and application of further genetic-molecular markers for diagnostic and prognostic purposes.