Molecular pathology of well-differentiated thyroid carcinomas.

The newly discovered molecular features of well-differentiated thyroid carcinomas derived from follicular cells are reviewed, within the frame of the 2004 WHO classification of thyroid tumours, under the following headings: "Follicular carcinoma", "Papillary carcinoma", "Follicular variant of papillary carcinoma" and "Hürthle cell tumours". A particular emphasis is put on the meaning of PAX8-PPARgamma rearrangements, RAS and BRAF mutations, and deletions and mutations of mitochondrial genes and of nuclear genes encoding for mitochondrial enzymes, for thyroid tumorigenesis.