Mediastinal Anaplastic Ependymoma.

Ependymomas arise from ependymal cells and can grow at any site in the central nervous system (CNS), as well as in some locations outside of the CNS. The latter is rare, contributing to the frequent misdiagnoses of such cases. Herein, we present the case of a 54-year-old man with a history of lower limb weakness and numbness. Magnetic resonance imaging revealed an extradural, heterogeneously enhanced solid lesion with a regular and well-defined border in the posterior mediastinum. A post-resection histopathological examination revealed tumor-forming perivascular pseudo-rosettes that showed immunoreactivity against glial fibrillary acidic protein, epithelial membrane antigen, and vimentin, as well as a high Ki-67 labeling index. Based on pathological features, a diagnosis of anaplastic ependymoma was established.