Brain–Tumor Interface, Brain Invasion, and Peritumoral Edema in Meningiomas: Pathology—Clinical Implications

Meningiomas are tumors arising from the arachnoid cap cells. Depending on their location along the meninges, they impact neighboring structures such as adjacent bone, vascular structures, cranial nerves, and central nervous system parenchyma. Especially, the brain–meningioma interface is an area where each lesion expresses properties that are decisive regarding its benign or more aggressive behavior. Especially, brain invasion has received increasing attention and has therefore been integrated into the WHO classification as a standalone criterion for atypia. However, there is a lasting debate about several aspects of brain invasion such as the true incidence, the impact of intraoperative sampling, imaging characteristics, and the conflicting data on its prognostic impact, which are discussed in this chapter together with the current clinical implications and potential future directions.