Histological images of suprasellar stereotactic brain biopsy specimen. Hematoxylin and eosin stained sections (A and B) show gliotic brain parenchyma with diffuse involvement by plasma cells, lymphocytes, and foci of histiocytes (A); high magnification of histiocytic aggregate shows cells with pale granular eosinophilic cytoplasm and grooved nuclei, indicated by arrows (B). Sections stained immunohistochemically for CD3 (C) and CD20 (D) show both T-cells and B-cells, respectively, within the lymphocytic infiltrates. In situ hybridization against kappa-light chain messenger ribonucleic acid (E) and lambda-light chain messenger ribonucleic acid (F) reveals a normal ratio of kappa-light chain to lambda-light chain expression. All histology images were captured using the following equipment: Olympus BX51 microscope, Olympus DP70 camera, and Olympus DP controller software. There was no image manipulation and scale bars were added in Photoshop, modeled over calibrated DP controller scale bars (not shown).