About 10% of ependymomas contain macroscopically visible cysts that are lined by ependymal cells mimicking small ventricles. With EMA, many of these cases show membrane positivity in tumor cells as depicted here. 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.