Meningithelial Meningioma

Loss of lobularity or a phenomenon known as "sheeting" is a common feature of atypical meningiomas; however, other criteria need to be fulfilled in order to upgrade these tumors. The picture portrays a meningothelial meningioma with loss of lobularity. Sheets of pink meningothelial cells are intersected by fibrovascular septae. Sometimes different histologic patterns of meningiomas coexist simulataneously within a tumor. They have been designated as "mixed meningioma". Mitotic activity is not seen in this picture.