Osteopontin immunohistochemistry in DLBCL. The immunoperoxidase complexes were visualized with diaminobenzidine (brown), and the sections were counterstained with hematoxylin. (A) PCNSL: original magnification ×200. Nearly every tumor cell of this brain biopsy is immunoreactive. (B) Nodal DLBCL: original magnification ×200. Essentially no tumor cell contains immunoreactivity. (C) Extranodal DLBCL (skin): original magnification ×200. Essentially no tumor cell contains immunoreactivity. (D) PCNSL: original magnification ×1000 oil. Cross section of a small vessel, probably a vein, surrounded by osteopontin-positive tumor cells.