Dural attachment
Extremely rare cases of supratentorial meningiomas without dural attachment have been described in adults. The uncommon locations of these tumors at sites distant from the dura mater is postulated to reflect the rare occurrence of arachnoidal cap cells in the Virchow-Robin spaces along the cerebral vasculature or in pial layers distant from the dura mater 1).
1)
Chiocca EA, Boviatsis EJ, Westmark RM, Short MP, Richardson EP, Zervas NT.
Deep sylvian fissure meningioma without dural attachment in an adult: case
report. Neurosurgery. 1994 Nov;35(5):944-6; discussion 946. Review. PubMed PMID:
7838346.