Two Translocations: a Follicular Variant 2; 18 and a Burkitt 8;14 in a Small Non Cleaved Non Hodgkin's Lymphoma

Philadelphia-like translocation t(9;22)(q34;q11) found in a follicular lymphoma involving not BCR and ABL but IGL-mediated rearrangement of an unknown gene on 9q34

In a case of follicular center cell lymphoma (FCCL) without evidence of histologic progression towards a high-grade lymphoma, t(9;22)(q34;q11) was found simultaneously with a t(14;18)(q32;q21) and a t(8;14)(q24;q32). Molecular studies of this case showed BCL2 and MYC rearrangements in addition to the rearrangements of immunoglobulin heavy (IGH) and lambda (IGL) loci. Investigation of the t(9;22) using Southern blot and RT-PCR analysis failed to detect M-bcr or m-bcr rearrangements of BCR. Two-color fluorescence in situ hybridization (FISH) with ABL and BCR probes revealed presence of a "fusion" signal, but its atypical localization [der(9)] and gene order [cen-ABL-BCR-tel] indicated that this translocation differed from the t(9;22) in chronic myeloid leukemia and did not involve either ABL or BCR. In addition, further FISH analysis using 9q34- and 22q11-specific probes localized the breakpoint on chromosome 9 distal to the NOTCH1 gene and the breakpoint on 22q11 in the IGL gene cluster. These results indicate an IGL-mediated rearrangement of an unknown gene at 9q34 that together with BCL2 and MYC might be involved in the lymphomagenesis of the present case of FCCL and perhaps in other cases of non-Hodgkin lymphoma in which t(9;22) is sporadically occurring.

Detection of PML-RAR alpha fusion transcript in Ph positive leukemia with acute promyelocytic phenotype lacking the t(15;17) cytogenetic abnormality

A 39-year-old woman was diagnosed with acute promyelocytic leukemia (APL) with disseminated intravascular coagulation syndrome. The hematologic examination showed a morphologic, cytochemical, and immunophenotypic picture typical of an APL, with a marked leukocytosis and a mixed population of hypergranular and microgranular promyelocytes. The cytogenetic analysis showed a 46,XX,t(9;22) karyotype, without any alterations of chromosomes 15 and 17. The t(15;17) translocation was not evident in FISH experiments, while a molecular analysis revealed the presence of a PML-RAR alpha chimera.

Molecular mapping of the chromosome 11 breakpoint of t(11;17)(q13;q21) in a t(11;14)(q13;q32)-positive B non-Hodgkin's lymphoma

The FAU gene is the cellular homologue of the viral FOX sequences in the genome of the Finkel-Biskis-Reilly murine sarcoma virus (FBR-MuSV); the viral FOX sequences have been shown to increase the transforming capacity of FBR-MuSV in vitro. The human FAU gene has recently been isolated, characterized, and mapped to chromosome band 11q13. Here, we report results of fluorescence in situ hybridization (FISH) analysis which indicate that the FAU gene maps proximally to the putative oncogene BCL1 at 11q13. Furthermore, we identified a t(11;17)(q13;q21) translocation in tumor cells of a t(11;14)(q13;q32)-positive B-cell non-Hodgkin's lymphoma patient by FISH analysis using a FAU containing cosmid clone as molecular probe and by double-colour chromosome painting analysis using chromosome 11- and chromosome 17-specific painting probes. The position of the chromosome 11 breakpoint of the t(11;17) translocation was pinpointed to a human DNA region around the FAU gene of about 40 kbp.

Combination of t(14;18) and a Burkitt's type translocation in B-cell malignancies

The combination of chromosomal translocations associated with bcl-2 rearrangement [t(14;18)] and c-myc rearrangement [t(8;14), t(8;22), or t(2;8)] has infrequently been detected in lymphoproliferative disorders. We have recently identified four cases of a B-cell malignancy exhibiting this dual translocation. In addition to t(14;18), one case had t(8;14) and three had the t(8;22). One case presented as de novo acute lymphoblastic leukemia (ALL-L2), two as de novo high grade lymphomas and the fourth evolved to a "blastic" phase from a previously documented follicular lymphoma. Immunophenotyping and molecular analysis was performed on three of the cases: all were negative for terminal deoxynucleotidyl transferase (TdT) but were CD10 positive. Two of the three cases with t(8;22) were negative for surface immunoglobulin (SIg) and positive for HLA-DR. Rearrangement of the oncogene bcl-2 was identified in a single case by polymerase chain reaction (PCR) only. Similar to cases reported in the literature, all patients had a poor clinical outcome despite aggressive therapy. Dual translocation lymphoid malignancy has a relatively characteristic morphology and the diagnosis should be considered when there is a history of an antecedent low grade lymphoma or when there is discordance between the "blastic" morphology and the immunophenotype (TdT- and/or SIg+). Confirmation requires demonstration of the characteristic translocations. Recognition of this entity has significant clinical implications that may require consideration of alternate treatment strategies.

t(2;18) and t(18;22) variant chromosomal translocations in B cell malignancies

Variant translocations (2;18 and 18;22) are described in this review. The chromosomal and molecular findings of these translocation of BCL2 and their effect on possible BCL2 gene activation is discussed. Unanswered questions still remain and these include why this is so rare compared to the 25% incidence recorded for translocations in Burkitt's lymphoma. Further studies are obviously still needed in order to determine the true frequency of these findings and their distribution in the various B-cell disorders.