Classification of meningiomas-advances and controversies.

Meningiomas are the most frequent primary central nervous system (CNS) tumors. Although approximately 80% of the tumors are slow growing and benign, some subtypes are associated with a less favorable outcome. An adequate classification system aims at providing a tool for estimating recurrence and overall survival of meningioma patients. The 2016 version of the World Health Organization (WHO) classification for CNS tumors constitutes a hallmark for neuropathological tumor classification since genetic alterations and histopathology are combined for a final diagnosis. Although this mainly applies to neuroepithelial tumors in meningioma research and classification the connection of histomorphological features and genetic profiles becomes more and more evident. Here we report on advances and controversies of meningioma classification in the 2016 edition of the WHO classification of CNS tumors. Furthermore we provide an outlook how a future meningioma classification system might look like.