April 2001: A 70 year old woman with recurrent 488 meningioma - Diagnosis - Meningothelial meningioma with simultaneous lipomatous and rhabdoid differentiation.

The April Case of the Month (COM). The contributors report a case of a 70 y ear-old woman with recurrent meningiomas, one of which showed rhabdoid and lipomatous differentiation. Histopathological study of the first and second previous resections showed only typical meningothelial meningioma. On the third craniotomy, a new tumor specimen showed an admixture of classic menin gothelial meningioma with lipomatous and rhabdoid foci. Immunohistochemical studies showed diffuse reactivity for epithelial membrane antigen and vime ntin, as well as focal positivity for desmin and smooth muscle actin in the areas with rhabdoid features and S100 protein in the lipomatous foci. The presence of these three different and concomitant histological patterns onl y in the third surgical resection might support a metaplastic origin and, a lso, corroborates the concept that rhabdoid features are suggestive of an a ggressive behavior.