Follicular Lymphoma grade 3B. A separate entity?

Een maligne lymfoom is een kwaadaardige woekering van witte bloedcellen die zich meestal manifesteert in lymfeklieren en zich verspreidt via het bloed- en/of lymfestelsel. Lymfomen kunnen in twee categorieën ingedeeld worden; de Hodgkin (HL) en non-Hodgkin lymfomen (NHL). In dit proefschrift worden alleen de NHL besproken. De NHL worden volgens de World Health Organization (WHO) classificatie in verschillende histologische subgroepen ingedeeld. Deze indeling vindt plaats op grond van een combinatie van genetische, histologische, immuunfenotypische en klinische eigenschappen en is belangrijk voor de behandeling. De twee meest voorkomende histologische subgroepen zijn de folliculaire lymfomen (FL) en de diffuus grootcellige lymfomen (DLBCL). FL worden volgens een microscopische methode, de ‘Berard cell counting methode’ in 3 subgroepen gegradeerd; FL graad 1,2 en 3. FL graad 3 kan op basis van de hoeveelheid centroblasten onderverdeeld worden in 3A en 3B. FL3A bestaat uit een gemengde populatie van centroblasten en centrocyten terwijl in FL3B alleen een monotone populatie van centroblasten voorkomt .... Zie: Nederlandse samenvatting

BCL6 alternative translocation breakpoint cluster region associated with follicular lymphoma grade 3B

Translocations involving band 3q27, affecting the major breakpoint region (MBR) of BCL6, are common in diffuse large B-cell lymphomas (DLBCLs). Recent data suggest an alternative breakpoint cluster region (ABR) located between 245 and 285 kb 5' of BCL6, which might be associated with Follicular Lymphoma (FL). Ten DLBCLs and 9 FLs grade 3B with cytogenetic rearrangements at 3q27 were studied by fluorescence in situ hybridization (FISH) to discriminate between breakpoints at the ABR and MBR. Eight DLBCLs contained a breakpoint in the MBR, and 6 FL grade 3B (FL3B) cases contained a breakpoint in the ABR. No specific chromosomal partners could be identified in both groups. Previously published data have suggested that FL3B cases with 3q27 aberrations are closely related to the majority of DLBCLs of germinal center cell origin. However, our findings suggest that the mechanism of 3q27 rearrangement in FL3B cases is similar to the mechanism in follicular lymphomas grade 1,2, and 3A cases. (c) 2005 Wiley-Liss, Inc

BCL6 alternative breakpoint region break and homozygous deletion of 17q24 in the nodular lymphocyte predominance type of Hodgkin's lymphoma-derived cell line DEV

DEV is the only cell line derived from nodular lymphocyte predominance type of Hodgkin's lymphoma (NLPHL); however, a comprehensive report about the genetic and immunophenotypic profile of this unique cell line is lacking. We analyzed DEV with respect to immunophenotype and genetic aberrations. The immunostaining revealed positivity for CD45, CD20, CD22, CD79a, IgA2, CD80, CD86, CD74, and BCL6. Cytogenetically, DEV has complex chromosome 3 translocations involving chromosomes 7, 14, and 22. A detailed analysis of the 3q27 breakpoint of the der(3)t(3;14)(p14;q32)t(3;22)(q27;q11.2) revealed a break in the BCL6 alternative breakpoint region. Using array comparative genomic hybridization, a 3-megabase homozygous deletion at 17q24.1-24.2 was identified. Fluorescence in situ hybridization indicated the presence of 2 chromosome 17 homologues, each of which carried a small interstitial deletion. Eight microsatellite markers flanking the homozygously deleted region all showed a homozygous pattern suggesting loss of one of the parental alleles. D17S1809 and D17S1816 could not be amplified using DEV DNA, in keeping with a location within the homozygously deleted segment. In conclusion, DEV has an immunophenotype that is consistent with the neoplastic cells of NLPHL cases, the lymphocytic and histiocytic cells. We demonstrated involvement of the BCL6 gene based on the presence of a breakpoint in the alternative breakpoint region and nuclear staining for BCL6 protein and identified a homozygously deleted region at 17q24. (c) 2006 Elsevier Inc. All rights reserved