RET and neoplasm: The quite different percentages of molecular alterations reported in different series of PDTC (e.g. BRAF mutations, RET/PTC rearrangement and β-catenin mutations), probably reflect the discrepancies in the classification and the heterogeneity of tumours that are often included under the umbrella category of PDTC (namely PTC with morphological signs of poor differentiation: solid, insular and trabecular foci).