Presentation
Headaches
Patient Data
There is a slightly hyperdense mass at the right occipital region. There is calcification within the lesion and perilesional vasogenic edema.
No change of the adjacent bone.
A supratentorial extra-axial mass with a broad dural base at the right occipital region. It is isointense in T1, hyperintense in T2/FLAIR, and intense, with homogeneous enhancement in T1C+.
There are peritumoral vasogenic edema and mass effect in the form of compressing adjacent brain parenchyma and right lateral ventricle.
The peripheral tumor has structures of high signal intensity in T2, fluid-attenuated in Flair, and no enhancement which consistent with cystic structures.
MRI findings show the typical features of an extra-axial tumor.
Blue arrows: Broad dural base and dural tail sign.
Orange arrow: CSF cleft sign.
Pink arrow: White matter buckling sign.
Case Discussion
CT and MRI features are most in keeping with a cystic meningioma that is an uncommon variant. This case can be classified as type 3 or 4 according to the Nauta et al. classification system 1.
The mechanisms of the cystic formation consist of degeneration or necrosis, direct secretion by meningioma, reactive changes. Nauta et al. divided cystic meningiomas into four subtypes according to the location of the cyst with respect to the brain and meningioma. The cysts can be entirely surrounded by tumor (types 1 or 2) or clearly between the tumor and the brain (type 5) or within the adjacent brain (type 4). However, it is sometimes difficult to distinguish between these types on imagings.