Clinicopathological study of gene rearrangement and microRNA expression of primary central nervous system diffuse large B-cell lymphomas

We studied the clinicopathological and imaging characteristics of primary central nervous system diffuse large B-cell lymphomas (PCNS-DLBCL). Imaging, pathologic histology, and immunohistochemical staining characteristics were analyzed, and the immunoglobulin heavy and light chain gene rearrangement of 25 PCNS-DLBCL cases was examined. MicroRNA was extracted from 10 cases each of PCNS-DLBCL, extracerebral germinal center DLBCL (GC-DLBCL), and extracerebral non-GC-DLBCL (NGC-DLBCL); we conducted chip hybridization and comparatively analyzed the difference among the three. PCNS-DLBCLs typically involved no less than two cerebral lobes (10/25); the frontal lobe was affected most often (6/25). Target-shaped structures were observed in all PCNS-DLBCLs due to the proliferation of centroblast-like large lymphocytes surrounding the vessels. There was strong and diffuse immunostaining for CD20 and CD79a, and negative immunostaining for CD3, CD5, CD23, and cyclin D1 for all PCNS-DLBCLs. The percentage of cells with nuclear positivity for anti-Ki67 antibody ranged 50-90% (mean, 80%). Three, 19, and 22 PCNS-DLBCLs were CD10-, Bcl-6-, and melanoma ubiquitous mutated 1-positive, respectively. Twenty-four PCNS-DLBCLs were B-cell monoclonal. MicroRNA hybridization showed that 788 PCNS-DLBCL microRNAs/segments increased to at least twice that of NGC-DLBCLs, and 401 PCNS-DLBCL microRNAs/segments declined to less than half of that of NGC-DLBCLs. Six hundred and eleven PCNS-DLBCL microRNAs/segments increased to at least twice that of GC-DLBCLs, and 229 PCNS-DLBCL microRNAs/segments declined to less than half of that in GC-DLBCLs. PCNS-DLBCL typically affected multiple sites, tended to occur in older men, arose from activated B cells, had high B-cell monoclonality; its microRNA expression differed from that of NGC-DLBCL and GC-DLBCL.