[Classification and Molecular Diagnosis of Benign Brain Tumors]

Classification and molecular diagnosis of benign brain tumors, focusing on cranial and pasaspinal nerve tumors, meningioma, mesenchymal, and non-meningothelial tumors involving the central nervous system(CNS)has been reviewed based on the 5^th edition of the World Health Organization Classification of Tumors of the Central Nervous System. In sporadic schwannomas, the novel fusion gene SH3PXD2A-HTRA1, which activates the MAPK pathway, has been discovered. Meningioma shows frequent chromosomal alterations, including at the NF2 locus. Recent genomic studies have investigated mutations in TRAF7, KLF4, AKT1, and SMO in sporadic meningiomas. In the 5^th edition, the meningioma should be graded regardless of the subtype. Thus, TERT promoter mutation and homozygous deletion of CDKN2A/B should be evaluated to define grade 2 and 3 meningiomas. In mesenchymal tumors, the term "hemangiopericytoma" has been deleted from solitary fibrous tumors.