BCA-1 expression in tonsil, brain, and PCNSL.

Immunohistochemical studies demonstrate that BCA-1 is not present in normal human brain (A) but is expressed in lymphoid follicles of tonsil (B) (Fast Red, hematoxylin counterstain, original magnification × 400). In tonsil, expression of SLC (C) and ELC (D) is localized to T-cell areas (Fast Red, hematoxylin counterstain, original magnification × 400). Brain biopsy specimen from a patient with PCNSL reveals widespread expression of BCA-1 (E), but not SLC (G) or ELC (H) within the tumor substance (Fast Red, hematoxylin counterstain, original magnification × 400). (F) Location of positive staining suggests that BCA-1 is expressed by malignant B cells and vascular endothelium (Fast Red, hematoxylin counterstain, original magnification × 1000).