Oil Red O stain on frozen sections can be helpful in the diagnosis of hemangioblastoma. Some cases contain only minute amount of lipid and the stain may not be strongly positive. 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.