The role of molecular pathology in thyroid cancer. Tumor diagnostics, cytology and targeted therapy

The diagnostics and differential diagnosis of tumors of the thyroid glands are still challenging. Molecular genetic insights are increasingly allowing a better definition of the various tumor entities. The role of molecular pathology in preoperative (e.g. fine needle biopsies) and postoperative diagnostics of thyroid tumors as well as an aid to decision making in targeted therapies of advanced stage thyroid cancer. A comprehensive summary based on relevant scientific and review articles in the literature. The traditional differentiation of thyroid carcinomas into four major groups (i.e. papillary, follicular, medullary and anaplastic carcinomas) based on morphology and clinical features is strongly supported by distinct genetic alterations in these four groups and with very little overlap. However, the morphologically and biologically relevant entity of poorly differentiated thyroid carcinoma still lacks a genetic definition. Molecular testing has been successfully included in the evaluation of fine needle thyroid biopsies. Currently available targeted therapies are based on genetic alterations, which are usually demonstrated by pathologists. In the future molecular pathology will most likely become an important tool in the decision-making process of targeted therapies in advanced and aggressive thyroid carcinomas. Molecular pathology has become an integral part of the diagnostic routine in the preoperative and postoperative evaluation, particularly of papillary thyroid carcinoma.