Lipomatous meningioma: Two case reports; [Méningiome lipomateux: À propos de deux cas]

Lipomatous meningiomas are rarely encountered and are included in the World Health Organization's (WHO) group of metaplastic meningiomas. We report two cases of these tumors. The presenting symptoms were headaches in one case and seizure in the other. Radiologically, these tumors were extra-axial and unique. One tumor displayed fat accumulation, while the other had the appearance of a conventional meningioma. Microscopically, these tumors corresponded to meningothelial and transitional meningiomas containing a variable proportion of adipose tissue composed of mature adipocytes or lipoblasts. Fat content was high in one case and moderate in the other, thus explaining the radiological findings. Expression of epithelial membrane antigen and progesterone receptors was present in meningothelial, adipocyte-like, and lipoblast-like cells. These immunohistochemical results suggest that lipid accumulation in meningioma should be considered a transformation of meningothelial cells rather than a true metaplasia. © Masson, 2005.