METAPLASTIC (LIPOMATOUS) MENINGIOMA: REPORT OF TWO CASES

Ferah  KARAYEL; Büge  ÖZ; Murat  İNAN; Bülent  CANBAZ

Lipomatous meningiom has been first described by Bailey et al. The name ‘Lipomatous Meningiom’ is a descriptive term, probably representing a predominantly lipocytic differentiation of the meningotheliomatous cells. Microscopically, the tumor composed of typical meningothelial cells with vesicular nuclei, inconspicious nucleoli and syntitial eosinophilic cytoplasm. In the tumor, vacuolated cells with either single or multipl vacuoles often resembling signet-ring cells were seen. Mitoses, necrosis and brain invasion were not seen. In the more classic meningotheliomatous areas, tumor cells were focally EMA and MAC-387 positive. The lipomatous areas were negative for these angitens. Meningioms may undergo particular forms of metaplasia, such as osteoid or chondroid. Diagnosis of metaplastic meningiomas is important in differential diagnosis, of more agressive tumors with different treatment and prognosis.