The 2007 WHO Classification of Tumors of the Central Nervous System was the last classification mainly based on microscopy features. The new 2016 WHO Classification of Tumors of the Central Nervous System was a paradigm shift: some of the tumors were defined also by their genetic composition as well as their cell morphology. The grading of gliomas changed importantly and glioblastoma was now mainly classified according to the status of isocitrate dehydrogenase (IDH) mutation: IDH-wildtype or IDH-mutant. Molecular alterations
Four subtypes of glioblastoma have been identified based on gene expression:
Classical: Around 97% of tumors in this subtype carry extra copies of the epidermal growth factor receptor (EGFR) gene, and most have higher than normal expression of EGFR, whereas the gene TP53 (p53), which is often mutated in glioblastoma, is rarely mutated in this subtype. Loss of heterozygosity  in chromosome 10 is also frequently seen in the classical subtype alongside chromosome 7 amplification. The proneural subtype often has high rates of alterations in TP53 (p53), and in PDGFRA, the gene encoding a-type platelet-derived growth factor receptor, and in IDH1, the gene encoding isocitrate dehydrogenase-1. The mesenchymal subtype is characterized by high rates of mutations or other alterations in NF1, the gene encoding neurofibromin 1 and fewer alterations in the EGFR gene and less expression of EGFR than other types.
Palpation thyroiditis refers to the development of thyroid inflammation due to mechanical damage to thyroid follicles. This can occur by vigorous repeated palpation (as with thyroid examination) or surgical manipulation (as can occur with radical neck dissection). It is a type of subacute thyroiditis. Pathology shows multifocal granulomatous folliculitis. T cells predominate compared to B cells. There may be initial transient hyperthyroidism due to leakage of preformed thyroid hormone in blood. == References ==