Metaplastic meningioma with lipomatous changes.

We report here relatively rare lipomatous metaplastic changes, probably related to a prolonged clinical course, in not otherwise specified transitional meningioma. This lesion appears to have evolved over 30 years, with the initial diagnosis of multiple sclerosis. Histologically, it was composed of clusters and whorls of polygonal and spindle cells characteristic for transitional meningioma, with large areas of cells with lipid cytoplasmic accumulation, closely resembling mature adipocytes. The lipidization of other brain tumors and the histogenesis of these lesions in meningiomas on the background of meningeal embryogenesis are also discussed.