Lipomatous meningioma: report of 2 cases and review of the literature

BACKGROUND: Lipomatous meningioma is a rare but, most of the time, benign tumor. Its pathogenesis is still debated: it is usually considered to be part of the metaplastic meningioma, but several authors recently suggested that fat accumulation inside the tumor was related to metabolic disorders of the meningothelial cells. CASES DESCRIPTION: We report 2 cases of lipomatous meningioma. Both patients were women older than 60 years. One patient suffered from headache and seizures, the other one presented with behavioral disturbance. Radiological features depended on the amount of fat accumulation within the tumor. Surgical treatment allowed complete resection in both cases without any complications. Both meningiomas were of transitional-type and were apparently composed of 2 populations of cells: meningothelial cells and lipid-laden cells resembling mature adipocytes. Immunohistochemical study showed that lipid-laden cells expressed EMA, CD99, and progesteron receptor, favoring a meningothelial differentiation rather than an adipocytic lineage. CONCLUSION: Our study strongly suggests that lipomatous meningioma results from an accumulation of lipid inside meningothelial cells rather than a true metaplasia.