CTLA4 and lymphoma: A comparison of the densities of CTLA-4+ cells in different tumor categories identified highest values in lymphomas (3642 ± 3207 cells/mm2), biphasic (609 ± 1057 cells/mm2) as well as germ cell tumors (401 ± 468 cells/mm2) and the lowest in mesothelial (281 ± 319 cells/mm2) as well as mesenchymal neoplasms (145 ± 268 cells/mm2; Table 1).