Anaplastic ependymomas are characterized by hypercellularity, increased mitotic activity, and microvascular proliferation. Ki67 labeling index is usually high. The example shown here had a Ki67 labeling index of around 50%. Courtesy of: Dr. Luciano de Souza Queiroz, Dept. of Pathology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, São Paulo State, BRAZIL. Additional images are here.