[A case of vacuolated meningioma]

A rare case of falx meningioma with extensive vacuolization was reported. A 57-year-old woman was admitted to Okayama University Hospital because of numbness in her left lower limb. A plain CT scan showed a hypodense mass in the right frontal region with marked enhancement after contrast medium injection. MRI on T1 weighted images showed low intense mass with the so-called "peritumoral band" of low intensity at the periphery of the mass. Angiogram showed a mass effect and a tumor stain fed by the right pericallosal artery and left middle meningeal artery. The mass was excised en bloc. Microscopic examination demonstrated tumor cells with varied sized vacuoles, which were mostly fat-negative, except for small islands with typical meningothelial cells in the periphery of the tumor. Ultrastructurally, there were two kinds of vacuole in the tumor cells. The smaller, round vacuoles were in the cytoplasm, while the larger ones were in the extracellular space. The cell processes had developed junctional complex, and numerous cytoplasmic filaments were evident. With these findings, this mass was diagnosed as vacuolated meningioma. It is important especially in frozen section not to misdiagnose the tumor as liposarcoma, chordoma, metastatic brain tumor and so on.