Eugenia Haralambieva

Enteropathy-Type T-Cell Lymphoma

Session 7 of the Society for Hematopathology/European Association for Haematopathology Workshop was devoted to case presentations and discussion of enteropathy-type T-cell lymphoma (ETL) and other T-cell lymphomas involving the gastrointestinal tract. ETL is a rare type of T-cell lymphoma, often associated with a history of celiac disease, that usually arises in the jejunum but can involve other gastrointestinal tract sites (eg, stomach and colon). As the cases submitted illustrate, there are 2 histologic groups of ETL that correlate with clinical and immunophenotypic features. Pleomorphic-anaplastic ETL is usually associated with a history of celiac disease and histologic evidence of enteropathy and is most often CD56-. Monomorphic ETL often occurs without a history of celiac disease, has variable histologic evidence of enteropathy, and is usually CD56+. Comparative genomic hybridization has shown recurrent chromosomal gains and losses that are characteristic of ETL and uncommon in other T-cell lymphomas, providing useful ancillary data for the diagnosis of ETL.

Genetic rearrangement of FOXP1 is predominantly detected in a subset of diffuse large B-cell lymphomas with extranodal presentation

Genetic rearrangement of FOXP1 is predominantly detected in a subset of diffuse large B-cell lymphomas with extranodal presentation

Combined functional and molecular analysis of tumor cell signaling defines 2 distinct myeloma subgroups: Akt-dependent and Akt-independent multiple myeloma

Although the phosphatidylinositide 3-kinase (PI3K)/Akt pathway has been reported to contribute to the malignant growth of multiple myeloma (MM), the true relevance of Akt kinases for this disease is still unclear. In particular, functional analyses in primary tumor cells and genetic target validation experiments are missing. Here, we used combined functional and molecular analyses to determine the importance of Akt activity in a large panel of primary MM samples and in MM cell lines. Akt down-regulation with isoform-specific siRNA constructs or with an Akt1/2-specific pharmacologic inhibitor strongly induced apoptosis in approximately half of the primary MM samples analyzed. Sensitivity to Akt inhibition strongly correlated with the activation status of Akt as determined by immunohistochemistry, phospho-Akt-specific flow cytometry, and Western analysis. Additional blockade of the MAPK and the IL-6R/STAT3 pathways was often not sufficient to decrease the viability of MM cells resilient to Akt inhibition. Taken together, these experiments led to the identification of 2 myeloma subgroups: Akt-dependent and Akt-independent MM.

Primary extramedullary plasmacytoma: similarities with and differences from multiple myeloma revealed by interphase cytogenetics

Primary extramedullary plasmacytoma and multiple myeloma show similar chromosomal alterations, as detected by fluorescence in situ hybridization. Primary extramedullary plasmacytoma is an indolent neoplasm that infrequently converts to multiple myeloma. Since cytogenetic data on extramedullary plasmacytoma are lacking, we studied 38 cases of this type of neoplasm by fluorescence in situ hybridization. Fourteen cases (37%) contained IGH breaks, including six with a t(4;14) translocation. No translocations t(11;14), t(14;16), t(8;14), nor breaks involving MALT1, BCL6 or FOXP1 were found. Loss of 13q (40%), as well as chromosomal gains (82%) were common. There was no correlation between chromosomal alterations and clinical features or local relapse. Cytogenetically, extramedullary plasmacytoma and multiple mueloma are closely related. However, the distribution of IGH translocation partners, with the notable absence of t(11;14), is different. Key words: extramedullary plasmacytoma, multiple myeloma, cytogenetics, IGH translocation, fluorescence in situ hybridization.

FOXP1 protein overexpression is associated with inferior outcome in nodal diffuse large B-cell lymphomas with non-germinal centre phenotype, independent of gains and structural aberrations at 3p14.1

Hoeller S, Schneider A, Haralambieva E, Dirnhofer S & Tzankov A
(2010) Histopathology 57, 73–80
FOXP1 protein overexpression is associated with inferior outcome in nodal diffuse large B‐cell lymphomas with non‐germinal centre phenotype, independent of gains and structural aberrations at 3p14.1

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 TCRα/δ, TCRβ, and TCRγ 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 TCRα/δ 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 TCRα/δ and the BCL3 loci. A second case, an angio‐immunoblastic T‐cell lymphoma (AILT), carried an inv(14)(q11q32) affecting the TCRα/δ 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. Copyright

Identification of chromosomal copy number changes associated with transformation of follicular lymphoma to diffuse large B-cell lymphoma

The histological transformation from a follicular lymphoma (FL) to a diffuse large B-cell lymphoma (DLBL) occurs in 22% to 30% of all cases of FL. The aim of this study was to identify specific chromosomal gains/losses associated with transformation of FL to DLBL, in addition to the well-known mechanisms like p53 mutation and protein expression and c-myc translocation and up-regulation. This is the first study to meet 2 important conditions for such a comparison. First, we demonstrate that the FL and the DLBL were clonally related, based on identical immunoglobulin gene rearrangements in 5 of the 6 cases. Second, we used laser microdissection microscopy to isolate only the neoplastic cells from the initial FL samples. The results indicate that no single chromosomal abnormality seems to be responsible for the transformation of FL to DLBL. P53 protein overexpression was found in 4 and c-myc translocation in 3 of the 6 transformed DLBLs, but not in the initial FL samples. Additional chromosomal abnormalities were detected by comparative genomic hybridization in all 6 cases when the DLBL was compared with the FL. In the 5 cases with transformation of grade 1 or 2 FL to DLBL, gains at chromosomes 7 (5 of 5 cases), 10p1 (3 of 5 cases), 12 (3 of 5 cases), and 20p13 (2 of 5 cases) and loss at 9q (4 of 5 cases) were the most frequently found abnormalities. A gain on chromosome 7p, in combination with a loss on 9q, was found in 4 of the 5 DLBL that transformed from FL grade 1 or 2.

Gain of chromosome region 18q21 including the MALT1 gene is associated with the activated B-cell-like gene expression subtype and increased BCL2 gene dosage and protein expression in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma is the most common lymphoma worldwide. Recent studies of gene expression profiling have identified subgroups of this lymphoid neoplasm with different prognosis. This study suggests that a gain of chromosome 18q21 including the MALT1 gene may involve an unfavorable prognosis. See related perspective article on page 641. Background The aim of this study was to determine the impact of a gain of the MALT1 gene on gene expression and clinical parameters in diffuse large B-cell lymphoma. Design and Methods We analyzed 116 cases of diffuse large B-cell lymphoma by fluorescence in situ hybridization, array-based comparative genomic hybridization, and transcriptional profiling. Results A gain of 18q21 including MALT1 was detected in 44 cases (38%) and was accompanied by a gain of BCL2 in 43 cases. All cases with a 18q21/MALT1 gain showed BCL2 protein whereas 79% in the group without a 18q21/MALT1 gain did so (p<0.001). Cases with 18q21/MALT1 gain more frequently showed an activated B-cell-like (ABC) gene expression signature (65%) than a germinal center B-cell-like (GCB) one (23%) (p<0.001). Ninety-eight genes including MALT1, BCL2, and some selected nuclear factor-κB target genes were differentially expressed between the two genetic groups of diffuse large B-cell lymphoma. By global testing of each chromosome, we identified 33 genes, all located on chromosome 18q, which were differentially expressed between the two genetic groups independently of the ABC/GCB status. In multivariate analysis, the 18q21/MALT1 status represented an independent negative prognostic factor for overall survival (p=0.03). Conclusions In diffuse large B-cell lymphoma, gain of 18q21 including MALT1 is significantly associated with differential expression of genes located on 18q, the ABC gene expression subtype, increased BCL2 gene and protein expression and might indicate an unfavorable prognosis.

Florid granulomatous reaction in Epstein-Barr virus-positive nonendemic Burkitt lymphomas - Report of four cases

Epithelioid cell granulomas have been reported in association with a wide range of neoplasms including malignant lymphomas. In lymphoma, this refers mainly to Hodgkin disease and T-cell-derived non-Hodgkin lymphomas where a granulomatous reaction is probably evoked by aberrant cytokine production in the tumor cells or other cells composing the tumor background. Here we report on four cases of sporadic Burkitt lymphoma with unusual florid granulomatous reaction. In all samples, the tumor cells were admixed with numerous epithelioid cells that formed clusters and granulomatous lesions. No microorganisms could be detected at the tissue level, and there were no clinical or laboratory indications of an underlying immunodeficiency. The lymphomas harbored a specific morphology and immunophenotype of Burkitt lymphoma, and the presence of translocation breakpoint in MYC gene was confirmed by interphase fluorescence in situ hybridization. In all four patients, the lymphoma was associated with Epstein-Barr virus infection, detected by EBER in situ hybridization and the latency I phenotype as defined by lack of expression of LMP1. All four patients were treated with polychemotherapy, achieved a complete remission, and are alive without evidence of disease. We draw attention to this unusual phenomenon as it caused difficulties in interpretation and delayed diagnosis and hypothesize on the possible role of Epstein-Barr virus products.

Non-IG Aberrations of FOXP1 in B-Cell Malignancies Lead to an Aberrant Expression of N-Truncated Isoforms of FOXP1

The transcription factor FOXP1 is implicated in the pathogenesis of B-cell lymphomas through chromosomal translocations involving either immunoglobulin heavy chain (IGH) locus or non-IG sequences. The former translocation, t(3;14)(p13;q32), results in dysregulated expression of FOXP1 juxtaposed with strong regulatory elements of IGH. Thus far, molecular consequences of rare non-IG aberrations of FOXP1 remain undetermined. Here, using molecular cytogenetics and molecular biology studies, we comprehensively analyzed four lymphoma cases with non-IG rearrangements of FOXP1 and compared these with cases harboring t(3;14)(p13;q32)/IGH-FOXP1 and FOXP1-expressing lymphomas with no apparent structural aberrations of the gene. Our study revealed that non-IG rearrangements of FOXP1 are usually acquired during clinical course of various lymphoma subtypes, including diffuse large B cell lymphoma, marginal zone lymphoma and chronic lymphocytic leukemia, and correlate with a poor prognosis. Importantly, these aberrations constantly target the coding region of FOXP1, promiscuously fusing with coding and non-coding gene sequences at various reciprocal breakpoints (2q36, 10q24 and 3q11). The non-IG rearrangements of FOXP1, however, do not generate functional chimeric genes but commonly disrupt the full-length FOXP1 transcript leading to an aberrant expression of N-truncated FOXP1 isoforms (FOXP1NT), as shown by QRT-PCR and Western blot analysis. In contrast, t(3;14)(p13;q32)/IGH-FOXP1 affects the 5′ untranslated region of FOXP1 and results in overexpress the full-length FOXP1 protein (FOXP1FL). RNA-sequencing of a few lymphoma cases expressing FOXP1NT and FOXP1FL detected neither FOXP1-related fusions nor FOXP1 mutations. Further bioinformatic analysis of RNA-sequencing data retrieved a set of genes, which may comprise direct or non-direct targets of FOXP1NT, potentially implicated in disease progression. In summary, our findings point to a dual mechanism through which FOXP1 is implicated in B-cell lymphomagenesis. We hypothesize that the primary t(3;14)(p13;q32)/IGH-FOXP1 activates expression of the FOXP1FL protein with potent oncogenic activity, whereas the secondary non-IG rearrangements of FOXP1 promote expression of the FOXP1NT proteins, likely driving progression of disease.