DEEP SYLVIAN FISSURE MENINGIOMA WITHOUT DURAL ATTACHMENT IN AN ADULT - CASE-REPORT

MENINGIOMAS ARE THOUGHT to arise from arachnoid cap or meningothelial cells that not only cluster on the surface of pacchionian granulations but also can cover the arachnoid membrane in other locations. This fr equent apposition to the dura mater probably accounts for the usual at tachment of the neoplasm to this layer. We report a deep sylvian fissu re meningioma without dural attachments in the right hemisphere of an adult patient. The patient initially presented with simple partial sei zures. Magnetic resonance imaging revealed a contrast-enhancing circul ar mass in the superior aspect of the insular region, deep to the infe rior parietal lobule. Surgical exploration confirmed the absence of du ral attachments. Microscopically, the tumor was found to be a sparsely cellular meningioma with an extensive collagenous matrix. A survey of the literature reveals that the majority of cases of meningiomas with out dural attachments occur either in children or below the tentorium. Extremely rare cases of supratentorial meningiomas without dural atta chment have been described in adults. The uncommon locations of these tumors at sites distant from the dura mater is postulated to reflect t he rare occurrence of arachnoidal cap cells in the Virchow-Robin space s along the cerebral vasculature or in pial layers distant from the du ra mater.