FISH studies in DLBCL: correlations with cell of origin: the Irish experience

Diffuse large B cell lymphoma (DLBCL) is the most common non-Hodgkin’s lymphoma, and while the majority of patients will be successfully treated using immunochemotherapy, a significant number, up to 30%, will either fail primary therapy or quickly relapse. Gene expression profiling (GEP) and the identification of rearrangements (R) involving MYC, BCL2 and/or BCL6 can be used to stratify patients with DLBCL into prognostic subgroups. GEP identifies three molecular subgroups, germinal centre B (GCB), activated B (ABC) and type 3, which reflect stages of GCB cell development. Patients in the GCB subgroup have the best prognosis, while those of ABC subtype have inferior overall survival rates.1 This ‘cell of origin’ (COO) classification is now a mandatory requirement in the diagnostic work-up of DLBCL. GEP is expensive however and not widely available, in contrast to immunohistochemistry (IHC). As such, IHC algorithms based on B cell differentiation antigens were developed, which are shown to have variable degrees of concordance with GEP.2 High-grade B cell lymphoma with MYC, BCL2 and/or BCL6 R also characterise a distinct group of aggressive lymphomas, known as double or triple hit lymphomas (DH/TH), and can occur in 5%–10% of DLBCL cases.3 DH/TH are usually associated …