They should not be confused with microcystic meningiomas, a distinct variant, in which the cysts are microscopic.
True cystic meningiomas (type 1 and 2 - see below) are those with a few large central cysts and are uncommon. Those with more numerous smaller peripheral cysts, are more common (up to 8 - 23% of cases). They are over-represented in male patients and the paediatric population 1.
Patients present clinically in the same way as patients with non-cystic meningiomas, with either symptoms related to increased intracranial pressure (ICP), focal neurology, or seizures.
Nauta et al divided cystic meningiomas into 4 subtypes according to the location of the cyst with respect to the brain and meningioma 3:
- type 1 : intratumoral cyst(s), located centrally within the meningioma
- type 2 : intratumoral cyst(s), located peripherally within the meningioma but still surrounded by tumour
- type 3 : cyst(s) located within the adjacent brain
- type 4 : cyst(s) located between the meningioma and brain (arachnoid cyst)
Various mechanisms have been proposed, and probably more than one is applicable depending on the location of the cysts:
- degeneration / necrosis
- direct secretion by meningioma
- reactive changes (peripheral arachnoid cysts)
The tumour itself has imaging features identical to non-cystic meningiomas (see meningioma article for a full discussion). The cysts are of variable size and can be entirely surrounded by tumour (types 1 or 2) or clearly between tumour and brain (type 4) or within the adjacent brain (type 3). On imaging it is sometimes difficult to distinguish between these types.
The differential is dependent on the location of the tumour. For tumours around the base of skull, cystic schwannomas (e.g. acoustic schwannoma, trigeminal schwannoma) are the main differential, as they share the bright contrast enhancement, and are commonly cystic when large.
- 1. Buetow MP, Buetow PC, Smirniotopoulos JG. Typical, atypical, and misleading features in meningioma. Radiographics. 1991;11 (6): 1087-106. Radiographics (abstract) - Pubmed citation
- 2. Drevelegas A. Imaging of Brain Tumors with Histological Correlations. Springer Verlag. (2010) ISBN:3540876480. Read it at Google Books - Find it at Amazon
- 3. Nauta HJ, Tucker WS, Horsey WJ et-al. Xanthochromic cysts associated with meningioma. J. Neurol. Neurosurg. Psychiatr. 1979;42 (6): 529-35. doi:10.1136/jnnp.42.6.529 - Free text at pubmed - Pubmed citation