Cystic Meningioma, an Uncommon Entity: A Case Report

Abstract

Cystic meningioma refers to meningothelial neoplasms or meningiomas associated with cyst formation. Clinical features depend on the tumors' size and location, and include symptoms of increased intracranial pressure, seizures, and focal neurological deficit. Four types of cystic meningiomas are described in the literature, suggested by Nauta et al., based on radiologic findings: Type I: Intratumoral cysts in which the tumor, macroscopically visible on all sides of the cyst, surrounds the cavity; Type II: Intratumoral cysts, lying at the periphery of the tumor and surrounded by a row of neoplastic cells, detectable microscopically; Type III: Peritumoral cysts, whose walls consisted partly of adjacent parenchyma and partly of the tumor; and Type IV: Peritumoral cysts, whose walls are formed by the arachnoid (arachnoid cyst), separated from the tumor by a distinct capsule. Theories proposed to explain cyst formation include degeneration or necrosis, direct secretion by meningioma, and reactive changes (peripheral arachnoid cysts). The tumor itself has features similar to non-cystic meningiomas. The cysts are usually of variable size and can be entirely surrounded by tumor (types I or II), clearly between the tumor and the brain (type IV), or within the adjacent brain (type III). On imaging, it is sometimes difficult to distinguish between these types. We herewith present two cases of cystic meningiomas.