Inv(14) with distal breakpoint in 14q32.1 in three cases of T cell lymphoma

Tissue microarray-based screening for chromosomal breakpoints affecting the T-cell receptor gene loci in mature T-cell lymphomas

The pathogenesis of mature T-cell non-Hodgkin lymphomas (T-NHLs) is poorly understood. Analogous to B-cell lymphomas, in which the immunoglobulin (IgH) receptor loci are frequently targeted by chromosomal translocations, the T-cell receptor (TCR) gene loci are affected by translocations in a subset of precursor T-cell malignancies. In a large-scale analysis of 245 paraffin-embedded mature T-NHLs, arranged in a tissue microarray format and using improved FISH assays for the detection of breakpoints in the TCRalpha/delta, TCRbeta, and TCRgamma loci, we provide evidence that mature T-NHLs other than T-cell prolymphocytic leukaemia (T-PLL) also occasionally show a chromosomal rearrangement that involves the TCRalpha/delta locus. In particular, one peripheral T-cell lymphoma (not otherwise specified, NOS) with the morphological variant of Lennert lymphoma displayed a chromosomal translocation t(14;19) involving the TCRalpha/delta and the BCL3 loci. A second case, an angio-immunoblastic T-cell lymphoma (AILT), carried an inv(14)(q11q32) affecting the TCRalpha/delta and IgH loci. FISH signal constellations as well as concomitant comparative genomic hybridization (CGH) data were also suggestive of the occurrence of an isochromosome 7, previously described to be pathognomonic for hepatosplenic T-cell lymphomas, in rare cases of enteropathy-type T-cell lymphoma.

Cytogenetic findings in 175 patients indicate that items of the Kiel classification should not be disregarded in the REAL classification of lymphoid neoplasms

Cytogenetics have proved to be a valuable tool for classifying systemic lymphatic neoplasms, as this technique allows different stem line aberrations and clonal developments to be distinguished. This study was designed to analyze how far groups defined according to common cytogenetic features correlated with their position in either the Kiel (KC) or the REAL classification. Cytogenetic analyses were performed on material from 175 patients with lymphoid neoplasms (LN). Samples were prepared from peripheral blood and bone marrow in acute lymphoblastic leukemia (ALL), from bone marrow in multiple myeloma (MM), and from lymph node biopsies in lymphomas. The results of this study support the inclusion of ALL, MM, and extranodal lymphomas into a comprehensive classification, because their chromosomal aberrations were always characteristic for LN. From the cytogenetic point of view, a subgroup of ALL appears as a leukemic manifestation of lymphoblastic lymphoma. MM have structural aberrations of chromosomes 1, 11, and 14 and secondary aberrations of chromosomes 3, 6, 7, 12, 13, and 18, all of which are characteristic for lymphatic disease. The groups with follicle center cell lymphoma and mantle cell lymphoma correlate well with our results both in the low-grade subtype and in the blastic variant type, the majority of cases demonstrating t(14; 18) and its variants and t(11; 14), respectively. In contrast, the group of diffuse large B-cell (DLB) lymphomas proved to be heterogeneous on the basis of our cytogenetic results. Accordingly, we would suggest keeping the immunoblastic lymphoma (IB) subtype defined by the KC. IB demonstrates no stem line aberration in common with any other group and seems to be characterized by stem line aberrations involving chromosomes 3 and 6. As some DLB lymphomas have a t(14;18) or variant translocations involving chromosome 18, they should either be separated as a subgroup or included into the group of follicle center lymphomas.

Classification of peripheral T-cell lymphomas: cytogenetic findings support the updated Kiel classification

The cytogenetic findings in peripheral T-cell lymphomas enabled us to distinguish not only between low and high grade peripheral T-cell lymphomas (PTL) but also between different morphologically defined subtypes. High grade lymphomas exhibited a higher frequency of aberrant clones, polyploid chromosome numbers, a higher complexity of aberrant clones and a lower proportion of normal metaphases than low grade PTL. Moreover, deletions in 6q, trisomies of 7q and monosomy 13 or changes of 13q14 were significantly more frequent in high grade than in low grade PTL. Translocation t(2;5)(p23;q35) was only seen in large cell anaplastic lymphoma. T-CLL/T-PLL was associated with the simultaneous presence of inversion inv(14)(q11q32.l) and trisomy 8q, mostly due to i(8q)(q10). Trisomy 3 was a characteristic chromosome aberration of lymphoepithelioid lymphoma, AILD-type T-cell lymphoma and T-zone lymphoma. In contrast to the other low grade PTL, AILD-type T-ceIl lymphoma and cutaneous T-cell lymphoma showed a high frequency of unrelated clones. In summary, the cytogenetic findings paralleled the histopathologic classification according to the updated Kiel classification and support the value of the distinction of the different morphologically defined entities.

Recurrent chromosome abnormalities in peripheral T-cell lymphomas

Cytogenetic findings in 45 cases of peripheral T-cell lymphomas (PTL) diagnosed according to the updated Kiel classification are reported. Recurrent numerical chromosome aberrations comprised -X, -Y, -13, +X, +3, +5 and +7. Recurrent structural aberrations included t/del(1)(p31-32), t(2;5)(p23;q35), dup(5)(q23q31-32), t/dup(6q), t/del(6q), trisomy 7q, and trisomy 8q, mostly due to i(8)(q10), and changes in 14q11 and 14q32.1, mostly due to inv(14)(q11q32.1), t/del(13)(q14), t(6;7)(q13;q13), and t(13;17)(q11-13;p11). All deletions in 6q involved band 6q21 and all partial trisomies of 7q led to an amplification of band 7q21. Further studies are needed to ascertain whether these cytogenetic findings in PTL are of clinical and prognostic significance.

Combined immunophenotyping and karyotyping in peripheral T cell lymphomas demonstrating different clonal and nonclonal chromosome aberrations in T helper cells

Combined immunophenotyping and karyotyping was performed in seven cases of peripheral T cell lymphoma with complex aberrant clones. Various lymphocytic cell populations entered mitosis, whereas all aberrant cells belonged to the T helper/inducer cell population. Lymphomas with the same recurrent chromosome aberrations, i.e. inversion inv(14)(q11q32.1) and isochromosome i(8)(q10), had a very similar immunophenotype. The aberrant cells in these cases expressed CD3+, CD4+, CD7+, CD45RO+. The immunophenotypic similarity is underlined in one case of T prolymphocytic leukemia, in whom the aberrant cells lost the CD8 antigen originally present, during cultivation with PHA. In one case of Sézary's syndrome, two or possibly even three different clones as well as nonclonal aberrations were identified within the T (helper/inducer) cell population, providing further evidence that chromosomal instability is a characteristic feature of cutaneous T cell lymphoma.

Prenatal detection of de novo paracentric inversion 46, XX inv (14) (q22q32.1) in a normal child: report and review of the literature

We present prenatal diagnosis and follow-up examination of an individual with a de novo paracentric inversion of the long are of chromosome 14. A literature search documented 19 other cases of paracentric inversion of 14q. The outcome of each of these cases is specified together with that of this current case. Four of the 20 cases, all XY, manifested significant abnormalities with mental retardation and microcephaly present in 3 of the 4 cases; 15% (2/13) of familial cases had abnormalities and 40% (2/5) of de novo cases had abnormalities.

Chromosome walking on the TCL1 locus involved in T-cell neoplasia

The TCL1 locus on chromosome 14 band q32.1 is frequently involved in the chromosomal translocations and inversions with the T-cell receptor genes observed in several T-cell tumors, including T-prolymphocytic leukemias, acute and chronic leukemias associated with the immunodeficiency syndrome ataxia-telangiectasia, and adult T-cell leukemia. All breakpoints cloned in this area have been mapped to 14q32.1, an area distant approximately 10,000 kb from the immunoglobulin heavy-chain gene locus on chromosome 14q band 32.3. Except for two cases of inversion, no physical linkage of the cloned breakpoints has been reported, nor has a gene been identified in this region. Taking advantage of chromosome-walking techniques and of the P1 phage, we cloned and characterized 450 kb of the germ-line TCL1 locus, starting from the breakpoints of two independent T-cell leukemias. We show that all molecular rearrangements characterized so far map to these clones, indicating not only that this region is the target of chromosomal rearrangements occurring in this area but also that both inversion and translocations occur within a 300-kb region in the T-cell leukemias. In the attempt to identify a candidate oncogene responsible for the malignant transformation, a CpG island centromeric to the inversions and to the translocations has been identified. Two probes near the CpG island have detected sequences conserved among species, as well as two transcripts in the K562 human erythroleukemia cell line. On the basis of these data, a model of activation of the putative TCL1 oncogene is suggested.

Clonal t(8;14)(p11;q31) in a case of reactive lymphoproliferation

A clone with an unbalanced translocation t(8;14)(p11;q31), resulting in deletion of the distal part of the long arm of chromosome 14, 14q31 --> 14qter, was detected in a case of Piringer's lymphadenitis. Histopathologically no atypical cells or other signs of malignant lymphoma were found. Southern blot analyses showed no rearrangement of the immunoglobulin heavy chain gene (IGH) or the T-cell receptor gamma chain (TCRG) gene. The case exemplifies that the detection of a chromosomally aberrant clone does not necessarily prove that a lymphoproliferative process is malignant.