Abstract
Cystic meningioma refers to meningothelial neoplasms or meningiomas associated with cyst formation. Clinical features depend on the tumorsâ 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.
Highlights
Cystic meningiomas are meningothelial neoplasms associated with cyst formation
Various types of cyst formation have been described in a cystic meningioma and these are classified according to radiologic findings by Nauta et al as follows: 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, separated from the tumor by a distinct capsule
All possible risks and benefits of surgical resection were discussed with the family, and once agreed surgery was offered to them
Summary
Cystic meningiomas are meningothelial neoplasms associated with cyst formation. True cystic meningiomas may show few large central cysts, these are most common type, and others may show more numerous smaller peripheral cysts. Various mechanisms have been proposed for formation of cysts in a cystic meningioma, and probably more than one is applicable, depending on the location of the cysts. These mechanisms include degeneration or necrosis in the meningioma, direct secretion by meningioma and reactive changes (peripheral arachnoid cysts). Various types of cyst formation have been described in a cystic meningioma and these are classified according to radiologic findings by Nauta et al as follows: 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
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