Histologic findings of LNs obtained from patients with DLBCL, NOS. (A) Increased infiltration of FOXP3-positive cells in the group of high levels of FOXP3-positive cells (immunostaining for FOXP3; objective magnification ×40). (B) Infiltration of FOXP3/CTLA-4 double-positive cells (arrows) in the group of high levels of FOXP3/CTLA-4 double-positive cells. FOXP3 stains the nuclei a brown color, and CTLA-4 stains the cytoplasm a red color (double immunostaining for FOXP3 and CTLA-4; objective magnification ×40).