Recent advances in subtyping tumors of the central nervous system using molecular data.

Primary brain tumors account for substantial morbidity and mortality. They often infiltrate the brain diffusely, continue growing, and cause adverse events, such as headaches, seizures, and neurological deficits. The classification of primary brain tumors, based for decades on histology, has been fundamentally changed by the World Health Organization in 2016 by incorporation of molecular data. Areas covered: Literature from glioblastomas, high- and low-grade astrocytic, oligodendroglial, glioneuronal and ependymal tumors from the last five years were reviewed. Results from comprehensive molecular profiling of neoplasms and impact of recent molecular subtyping on neuropathological diagnosis are presented. Expert commentary: The identification of frequent acquired mutations shows that adult and pediatric glioblastomas have divergent biology with differing prognoses. Astrocytoma and oligodendroglioma are more closely related than previously thought. Molecular profiling now enables the precise classification of most diffuse gliomas into three clinically and therapeutically different subtypes according to the presence or absence of IDH mutation and 1p/19q codeletion. New subgroups with different clinical outcomes and anatomic locations have emerged in ependymomas and pediatric embryonal tumors.