Gain of chromosome arm 9p is characteristic of primary mediastinal B-cell lymphoma (MBL): Comprehensive molecular cytogenetic analysis and presentation of a novel MBL cell line

Primary mediastinal B-cell lymphoma (MBL) is an aggressive Non-Hodgkin's Ly mphoma. which has been recognized as a distinct disease entity. We performe d a comprehensive molecular cytogenetic study analyzing 43 MBLs. By compara tive genomic hybridization (CGH), the most common aberrations were gains of chromosome arms 9p and Xq, which were present in 56% and 40% of cases, res pectively. Based on the limited resolution of CGH, this technique may under estimate the real incidence of aberrations. Therefore, we also did an inter phase cytogenetic study with eight DNA probes mapping to chromosome regions frequently altered in B-cell lymphomas. With this approach, both 9p and Xq gains were found in more than 70% of cases (75% and 87%, respectively). Th e findings were compared with results obtained in 308 other B-cell lymphoma s. Gains in 9p were identified in only six of the 308 cases, and only one o f these lymphomas with 9p gains was not primarily extranodal in origin (P < 10(-20) for CGH data and P < 10(-11) for fluorescence in situ hybridizatio n data). We also present a novel MBL cell line, MedB-I, which carries the g enetic aberrations characteristic of this entity. (C) 2001 Wiley-Liss, Inc.