Interface between the meningioma and the brain.

Though meningiomas are usually well demarcated from the brain, their interfaces with the brain take various forms. Based on 27 nonoperated supratentorial meningiomas from autopsies, the interfaces were classified into four types, that is, smooth, lobular, finger-like expansion, and invasive. Relationships between the types of interfaces and the so-called capsule of the tumor and subarachnoid vessels are discussed. Additionally, three surgical cases which showed more or less the invasive form are presented with neuroradiological findings.