In multivariate analysis, proliferative activity as measured by MIB1 score has been shown to have independent prognostic value. Higher scores are linked with adverse outcome. In this case, Ki-67 appears to be positive in almost 70% of the nuclei (by visual estimation), consistent with rapid tumor growth. 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.