Low- and high-density PCNSL tumors. Low-density (A) and high-density (B) PCNSL tumors, each of large B-cell histology, are distinguished by the presence (A) or absence (B) of intervening normal brain elements between the tumor cells in pathologic specimens. Magnification ×100 (hematoxylin and eosin). Image were photographed using an Olympus Vanox AHBT3 microscope with Olympus DP70 digital camera (Olympus Optical, Tokyo, Japan). Images were captured onto a personal computer using Olympus DP controller software, version 1.2.1.108.