Discordant intracellular and plasma D-2-hydroxyglutarate levels in a patient with IDH2 mutated angioimmunoblastic T-cell lymphoma.

OBJECTIVES: Angioimmunoblastic T-cell lymphoma (AITL) is an aggressive peripheral T-cell lymphoma with mutations in genes encoding isocitrate dehydrogenase1 and 2 (IDH1 and IDH2). Mutant IDH generates the oncometabolite D-2-hydroxyglutarate (D-2HG). We report the first case of discordant intracellular and plasma D-2HG levels in a patient with IDH2 R172S mutated AITL. METHODS: An 87-year-old woman was diagnosed with AITL in the groin lymph node by morphologic and immunophenotypic analyses, and molecular studies by DNA sequencing. D-2HG was measured in both tumoral tissue and in pre-treatment plasma by liquid chromatography-tandem mass spectrometry. RESULTS: While D-2HG was markedly elevated in the tissue sample, its level in plasma was normal. We discuss this discordant D-2HG result within the context of previously reported discordant 2HG results in other IDH mutated tumors, and its implication for using circulating D-2HG as a biomarker of IDH mutation. In addition, this case also harbored mutations in RHOA, TET2, and TP53. The molecular pathogenesis is briefly discussed. CONCLUSION: While our case suggests that circulating D-2HG is not a reliable marker of IDH mutation in AITL, more cases need to be studied to arrive at a definite conclusion.

[Presence of B-cell clones in angioimmunoblastic T cell lymphoma].

OBJECTIVE: To study the significance of B-cell clones in angioimmunoblastic T cell lymphoma (AITL) and the correlation with Epstein-Barr virus (EBV) and prognosis. METHOD: The histopathologic features, T cell clonality and EBV positivity in 33 cases of AITL and 10 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) collected from May 2010 to February 2014 were analyzed by immunohistochemistry, PCR gene rearrangement and in situ hybridization. Follow-up data were also collected. RESULTS: Of the 33 cases with AITL, seven cases (21.2%) exhibited clonal rearrangement of Ig genes; 21 cases (63.6%) were EBV positive. Seven cases had B-cell clones and all (7/7) were EBV positive; 14 of the 26 (53.8%) cases without B-cell clones were EBV positive. The difference between the two groups was statistically significant (P = 0.032). Four levels were made according to the number of EBV-labeled cells, Ig gene rearrangements, but there was no significant difference among levels 1, 2 and 3. There was no correlation between B-cell clones and prognosis (P = 0.263). CONCLUSION: Clonal rearrangement of Ig genes is a common finding in AITL, and it is highly associated with EBV positivity, but not with the number of EBV-labeled cells. The clinical significance remains unclear; further study with more samples is warranted.

Diffuse large B-cell lymphomas of immunoblastic type are a major reservoir for MYC-IGH translocations.

The immunoblastic variant of diffuse large B-cell lymphoma (IB-DLBCL) has recently been recognized as an aggressive lymphoma type with inferior prognosis as compared with other DLBCL variants. At the same time, the presence of MYC rearrangements in DLBCL has been shown to indicate shorter survival in R-CHOP-treated patients. In this study, we investigated the occurrence of MYC gene rearrangements in IB-DLBCL versus non-IB-DLBCL in a large series. Using fluorescence in situ hybridization with an MYC break-apart and MYC-IGH fusion probe, we found that 13/39 evaluable IB-DLBCLs (33%) harbor translocations involving MYC, in contrast with only 5/68 (7%) in the non-IB-DLBCL group (P<0.01). The immunoglobulin heavy chain gene (IGH) was the translocation partner in all rearrangements (100%) involving MYC in IB-DLBCL, which is in contrast to what has been reported for DLBCL in the literature (50% to 70%). Moreover, MYC rearrangements occurred as the sole translocation in the majority of cases (77%), whereas across all DLBCLs the majority of MYC-rearranged cases carry additional rearrangements of either BCL2 and/or BCL6 genes (between 58% and 83% of cases). Finally, MYC-rearranged IB-DLBCLs were CD10 positive in 62% (8/13), whereas this was an uncommon feature in MYC germline IB-DLBCLs (15%). In conclusion, IB-DLBCLs are genetically characterized by frequent MYC-IGH translocations that often occur without additional BCL2 and/or BCL6 translocations. The activation of MYC, therefore, may be an important pathogenetic feature in IB-DLBCL.

Plasmablastic lymphoma of the stomach in an HIV-negative patient.

Plasmablastic lymphoma (PBL) is a rare B-cell neoplasm with an aggressive clinical behavior that predominantly occurs in the oral cavity of human immunodeficiency virus (HIV)-positive patients. However, it has recently been recognized that PBLs can also affect individuals without HIV infection, and suggested that these neoplasms show different clinicopathological characteristics between HIV-positive and -negative patients. Herein we describe a case of gastric PBL in a female HIV-negative patient. The tumor was composed of a diffuse and cohesive proliferation of large neoplastic cells, which resembled immunoblasts or plasmablasts with a starry sky appearance. Immunophenotypically, the neoplastic cells were diffusely positive for CD138, MUM1, IgM, and BOB-1, and negative for CK, LCA, CD3, CD20, CD79a, Pax5, kappa, lambda, CD30, ALK, S-100, HMB-45, MPO, and HHV-8. The MIB-1 index was nearly 100%. Epstein-Barr virus-encoded RNA in situ hybridization was negative. A monoclonal immunoglobulin heavy chain gene rearrangement was detected in polymerase chain reaction (PCR) and heteroduplex analyses. A combination of PCR-based analysis of immunoglobulin gene rearrangement and immunohistochemistry can be useful to substantiate the diagnosis by utilizing routine paraffin-embedded tissue sections, because PBL in the setting of extra-oral localization and immunocompetence is a diagnostic challenge, given its rarity, morphology, and absence of CD20 expression.

Clinicopathologic analysis of peripheral T-cell lymphoma, follicular variant, and comparison with angioimmunoblastic T-cell lymphoma: Bcl-6 expression might affect progression between these disorders.

We examined clinicopathologic findings in 17 cases of peripheral T-cell lymphoma, follicular variant (f-PTCL), and compared these findings with angioimmunoblastic T-cell lymphoma (AITL) to determine whether they were identical to the spectrum of changes seen in AITL and how each of the findings in f-PTCL were related to the characteristics of AITL. Almost all f-PTCL cases showed pathologic characteristics of AITL and immunohistochemical positivities in lymphoma cells for CD4, CD10, Bcl-6, PD-1, and CXCL13. Except for pathologic characteristics, clinicopathologic findings in f-PTCL had few significant differences from AITL. The positive rate for Bcl-6 expression in neoplastic cells was significantly associated with the frequency of polymorphic infiltrates, vascular proliferation, B-immunoblasts, clear cells, Epstein-Barr virus-positive lymphocytes, hepatosplenomegaly, and skin rash. Our study confirmed the continuity between f-PTCL and AITL. Moreover, Bcl-6 expression in f-PTCL was statistically associated with the characteristics of AITL.

Transformation of follicular lymphoma to plasmablastic lymphoma with c-myc gene rearrangement.

Follicular lymphoma (FL) is an indolent lymphoma that transforms to high-grade lymphoma, mostly diffuse large B-cell lymphoma, in about a third of patients. We present the first report of a case of FL that transformed to plasmablastic lymphoma (PBL). Clonal transformation of the FL to PBL was evidenced by identical IGH/BCL2 gene rearrangements and VDJ gene usage in rearranged IGH genes. IGH/ BCL2 translocation was retained in the PBL, which also acquired c-myc gene rearrangement. Genealogic analysis based on somatic hypermutation of the rearranged IGH genes of both FL and PBL suggests that transformation of the FL to PBL occurred most likely by divergent evolution from a common progenitor cell rather than direct evolution from the FL clone. Our study of this unusual case expands the histologic spectrum of FL transformation and increases our understanding of the pathogenetic mechanisms of transformation of indolent lymphomas to aggressive lymphomas.

Genomic profiling of plasmablastic lymphoma using array comparative genomic hybridization (aCGH): revealing significant overlapping genomic lesions with diffuse large B-cell lymphoma.

BACKGROUND: Plasmablastic lymphoma (PL) is a subtype of diffuse large B-cell lymphoma (DLBCL). Studies have suggested that tumors with PL morphology represent a group of neoplasms with clinopathologic characteristics corresponding to different entities including extramedullary plasmablastic tumors associated with plasma cell myeloma (PCM). The goal of the current study was to evaluate the genetic similarities and differences among PL, DLBCL (AIDS-related and non AIDS-related) and PCM using array-based comparative genomic hybridization. RESULTS: Examination of genomic data in PL revealed that the most frequent segmental gain (> 40%) include: 1p36.11-1p36.33, 1p34.1-1p36.13, 1q21.1-1q23.1, 7q11.2-7q11.23, 11q12-11q13.2 and 22q12.2-22q13.3. This correlated with segmental gains occurring in high frequency in DLBCL (AIDS-related and non AIDS-related) cases. There were some segmental gains and some segmental loss that occurred in PL but not in the other types of lymphoma suggesting that these foci may contain genes responsible for the differentiation of this lymphoma. Additionally, some segmental gains and some segmental loss occurred only in PL and AIDS associated DLBCL suggesting that these foci may be associated with HIV infection. Furthermore, some segmental gains and some segmental loss occurred only in PL and PCM suggesting that these lesions may be related to plasmacytic differentiation. CONCLUSION: To the best of our knowledge, the current study represents the first genomic exploration of PL. The genomic aberration pattern of PL appears to be more similar to that of DLBCL (AIDS-related or non AIDS-related) than to PCM. Our findings suggest that PL may remain best classified as a subtype of DLBCL at least at the genome level.

No evidence for the JAK2 (V617F) or JAK2 exon 12 mutations in primary mediastinal large B-cell lymphoma.

Dysregulated JAK2 signaling has been shown to play a significant role in the pathogenesis of myeloproliferative disorders. Recently, our work comparing gene expression signatures of primary mediastinal large B-cell lymphomas (PMLBCL) versus nodal diffuse large B-cell lymphomas revealed a relative increase in JAK2 transcripts in the former, suggesting a role for increased JAK2 signaling in a subset of these tumors. Given the likelihood of increased JAK2 signaling in PMLBCL, we sought to determine whether JAK2 activating mutations were an alternative mechanism for increased JAK2 signaling in untreated PMLBCLs. We performed amplification refractory mutation analysis for the JAK2 (V617F) mutation and bidirectional sequencing for the recently described JAK2 exon 12 mutations on genomic DNA isolated from a well-characterized cohort of PMLBCLs. No evidence of the mutant JAK2 (V617F) allele or JAK2 exon 12 mutations was detected in 31 PMLBCL cases tested. Analysis using cell lines derived from PMLBCLs (n = 1) and from the molecularly similar classic Hodgkin lymphoma (n = 4) also failed to reveal involvement of a mutant JAK2 allele. Taken together, these results suggest that JAK2 signaling in PMLBCLs occurs by mechanisms distinct from JAK2 (V617F) or JAK2 exon 12 activating mutations.

Human immunodeficiency virus-negative plasmablastic lymphoma in Korea.

Plasmablastic lymphoma (PBL) is very rare, and predominantly occurs in Human immunodeficiency virus (HIV)-positive individuals. It shows a strong affinity for the oral cavity and for the Epstein-Barr virus (EBV) positive. We investigated the clinicopathologic characteristics of six cases of PBL in Koreans. All patients were HIV-negative and without underlying immunodeficiency. The age distribution was bimodal, and four patients were older than 60 years. Male predominance was observed with male to female ratio of 5:1. The organs primarily involved were the terminal ileum, stomach, oral cavity, tonsil, nasal cavity and meninges. The tumors were histologically typical of PBL. Three of them were composed of monomorphic large immunoblastic or plasmablastic cells, and classified as PBL of the oral mucosa type. Another three cases were classified as PBL with plasmacytic differentiation. Five cases revealed loss of B-cell antigens with CD138 or MUM1 substitution. CD10 was positive in two cases (PBLs of the oral mucosa type), and one of them unexpectedly expressed cytokeratin. EBV was detected in one case (PBL with plasmacytic differentiation). Four patients succumbed to PBL in a relatively short period of time. We suggest that PBL is not strongly associated HIV or EBV in Koreans, and that it shows a variable organ distribution without an oro-nasal predilection.

AIDS-related plasmablastic lymphoma of the oral cavity associated with an IGH/MYC translocation--treatment with autologous stem-cell transplantation in a patient with severe haemophilia-A.

Plasmablastic lymphoma is an AIDS related lymphoma that continues to have a poor prognosis despite significant advances in the management of HIV and lymphoproliferative diseases. In part this has been due to limited insights into the biology of this disease and the molecular mechanisms of oncogenesis. To date molecular abnormalities have not been described in plasmablastic lymphoma, and its aggressive clinical behaviour has been difficult to understand. We describe the first reported cytogenetic abnormality in plasmablastic lymphoma, an IgH/MYC translocation. It is also the first description of autologous stem cell transplantation in a patient with severe haemophilia A.

Plasmablastic lymphoma of head and neck: report of two new cases and correlation with c-myc and IgVH gene mutation status.

Plasmablastic lymphoma (PBL) is a rare acquired immunodeficiency syndrome-associated non-Hodgkin's lymphoma (AIDS-NHL), with predilection for the mucosa of oral cavity. It usually has a plasmablastic morphology, expressing plasma cell-associated antigens with weak or absent expression of B-cell-associated markers. To further define the immunophenotypic and molecular genetics of these tumors, we investigated two cases of plasmablastic lymphomas of the head and neck for c-myc gene rearrangement and immunoglobulin heavy chain (IgV(H)) hypermutation status. For the first time we report a case of AIDS-related PBL that, by fluorescence in situ hybridization (FISH), shows a c-myc gene rearrangement. Although current literature suggests that most cases of c-myc gene rearranged AIDS-NHL are Burkitt's lymphoma, our case has an immunophenotype characteristic for PBL. In this case, IgV(H) hypermutation analysis showed a somatic hypermutation, indicative of germinal center transit. The concurrent B-cell immunophenotype of BCL-6(-)/CD138(+)/MUM-1(+) also suggests a post-germinal center B-cell origin of this lymphoma. The immunophenotype of our second case (BCL-6(-)/CD138(+)/MUM-1(+)) also suggests a post-germinal center B-cell origin. However, IgV(H) hypermutation analysis was not possible in this case.

Mechanisms and effects of loss of human leukocyte antigen class II expression in immune-privileged site-associated B-cell lymphoma.

PURPOSE AND EXPERIMENTAL DESIGN: Loss of human leukocyte antigen (HLA) expression on tumor cells is frequent in diffuse large B-cell lymphoma (DLBCL) arising in immune-privileged sites, such as the testis and central nervous system, and is associated with small homozygous deletions of HLA-DQ/HLA-DR and larger hemizygous deletions of the MHC region. To better understand the significance of down-regulation of HLA class II expression in relation to the homozygous and hemizygous deletions, we analyzed global gene expression patterns in a series of 26 testicular DLBCL after characterization of these deletions. RESULTS: Low levels of HLA-DR mRNA in whole testicular DLBCL samples were associated with a strong down-regulation of numerous immune-related genes specific for T cells, macrophages, antigen presentation and processing, lymphocyte activation, chemokines and chemokine receptors, and the complement system. The number of CD3+ tumor-infiltrating T cells was also significantly lower in low expressors of HLA-DR mRNA. Interestingly, hemizygous and homozygous deletions in the MHC region did not have any additional effect on global gene expression. CONCLUSION: In conclusion, we found that loss of HLA class II mRNA expression in testicular DLBCL is associated with a significant change in global gene expression patterns. This effect is independent of the mechanism causing the down-regulation of HLA class II genes in the lymphoma cells.

Large cleaved and immunoblastic lymphoma may represent two distinct clinicopathologic entities within the group of diffuse large B-cell lymphomas.

PURPOSE: The reliability of immunohistochemistry for subdividing diffuse large B-cell lymphomas (DLBCL) into germinal center B-cell-like (GCB) and non-GCB prognostic subgroups is debated. In this study we evaluated the prognostic significance of such subgrouping on a series of 153 DLBCL patients. Furthermore, we investigated whether both subgroups could comprise clinicopathologic entities recognized by their morphology and characterized by a distinct phenotype, specific genetic abnormalities, and clinical characteristics. PATIENTS AND METHODS: All samples from patients were reviewed and morphologically subdivided into large cleaved, immunoblastic, and not otherwise specified DLBCL. GCB and non-GCB immunohistochemical profiles were established. The presence of chromosomal translocations involving BCL2, BCL6, and MYC and/or rearrangements of these genes was investigated. RESULTS: Subdividing DLBCL with either a GCB or non-GCB immunophenotypic profile was not of prognostic significance. Nevertheless, CD10 expression was a predictor of favorable outcome, whereas high bcl-2 expression and BCL6 rearrangement were adverse predictors of disease-free survival. Interestingly, large cleaved DLBCL was clearly associated with a GCB immunophenotypic profile, CD10 expression, BCL2 rearrangement, age younger than 60 years, and low to low/intermediate International Prognostic Index risk, but was not of prognostic significance. In contrast, immunoblastic morphology was associated with a non-GCB profile and was a significant predictor of unfavorable DFS. CONCLUSION: Subdividing DLBCL into subgroups based on their immunohistochemical profile was not of prognostic significance. Nevertheless, it allowed the additional characterization of two lymphoma subgroups previously recognized in the Working Formulation. Both correspond to two distinct clinicopathologic entities within the DLBCL.

Richter's syndrome: biology and therapy.

Richter's syndrome, that is, transformation of chronic lymphocytic leukemia to a large cell or immunoblastic lymphoma, occurs in up to 10% of patients with chronic lymphocytic leukemia. The onset of Richter's syndrome is characterized by worsening systemic symptoms, rapid tumor growth, and/or extranodal involvement. Median survival with conventional chemotherapy is less than 6 months. Therapy with more recent therapeutic regimens, such as hyperCVXD (fractionated cyclophosphamide, vincristine, liposomal daunorubicin, and dexamethasone), augmented hyperCVXD, and yttrium-90 ibritumomab tiuxetan, has not produced major improvements in response rates or overall survival. Improvement in the outcome of patients with Richter's syndrome may be aided by a more comprehensive understanding of the pathogenesis of Richter's syndrome; therapy could then be targeted against specific abnormalities. Current data indicate that the transformation of chronic lymphocytic leukemia to a large-cell or immunoblastic lymphoma is associated with abnormalities in cell cycle regulation (e.g., loss of the cell cycle inhibitors p16(INK4a) and p27(KIP1) ) and DNA repair (e.g., mutations and/or deletions of the p53, ATM, and p14(ARF) genes and epigenetic silencing of the MLH1 gene). However, the critical event leading to transformation is unclear. Given the poor prognosis of patients with Richter's syndrome, every effort should be made to enroll these patients into clinical trials evaluating novel agents with the appropriate correlative studies.

Emerging pathways in the development of AIDS-related lymphomas.

The clinicopathological range of AIDS-related non-Hodgkin lymphomas (NHLs) includes systemic lymphomas, primary central-nervous-system lymphomas, primary effusion lymphoma, and plasmablastic lymphoma of the oral cavity. Most AIDS-related NHLs belong to one of three categories of high-grade B-cell lymphomas: Burkitt's lymphoma, centroblastic lymphoma, and immunoblastic lymphoma. The pathological heterogeneity of AIDS-related NHL reflects the heterogeneity of their associated molecular lesions. In AIDS-related Burkitt's lymphoma, the molecular lesions involve activation of c-MYC, inactivation of p53, and infection with Epstein-Barr virus (EBV). AIDS-related immunoblastic lymphomas infected with EBV are characterised by frequent expression of latent membrane protein 1-an EBV oncoprotein. The biological heterogeneity of AIDS-related NHLs is highlighted by their histogenetic differences; AIDS-related NHLs are related to distinct B-cell subgroups (eg, germinal-centre or post-germinal-centre B cells). The phenotypic pattern of AIDS-related Burkitt's lymphomas and systemic AIDS-related centroblastic lymphomas closely reflects that of B cells in germinal centres. Conversely, the phenotype of AIDS-related immunoblastic lymphomas and AIDS-related primary effusion lymphomas reflects post-germinal-centre B cells in all cases. Despite their clinicopathological, genetic, and phenotypic heterogeneity, most lymphomas in patients with AIDS carry somatic mutations of immunoglobulin and BCL-6 genes. However, the somatic hypermutation mechanism functions aberrantly in a significant proportion of AIDS-related NHLs, causing the mutation of many genes, and possibly favouring chromosomal translocation, which may be a powerful contributor to malignant transformation. New molecular and virological evidence of such pathways and a greater knowledge of other biological features of AIDS-related NHLs may lead to new targets for pathogenetically and biologically oriented therapies.

Heterogeneous breakpoints on the immunoglobulin genes are involved in fusion with the 5' region of BCL2 in B-cell tumors.

The 5' flanking region of the BCL2 gene (5'-BCL2) is a breakpoint cluster of rearrangements with immunoglobulin genes (IGs). In contrast to t(14;18)(q32;q21) affecting the 3' region of BCL2, 5'-BCL2 can fuse to not only the heavy chain gene (IGH), but also two light chain gene (IGL) loci. We report here cloning and sequencing of a total of eleven 5'-BCL2 / IGs junctional areas of B-cell tumors, which were amplified by long-distance polymerase chain reaction-based assays. The breakpoints on 5'-BCL2 were distributed from 378 to 2312 bp upstream of the translational initiation site and, reflecting the alteration of regulatory sequences of BCL2, 5'-BCL2 / IGs-positive cells showed markedly higher levels of BCL2 expression than those of t(14;18)-positive cells. In contrast, the breakpoints on the IGs were variable. Two 5'-BCL2 / IGH and two 5'-BCL2 / IGLkappa junctions occurred 5' of the joining (J) segments, suggesting operation of an erroneous variable (V) / diversity (D) / J and V / J rearrangement mechanism. However, two other 5'-BCL2 / IGH junctions affected switch regions, and the kappa-deleting element, which is located 24 kb downstream of the constant region of IGLkappa, followed the 5'-BCL2 in another case. One 5'-BCL2 / IGLkappa and two 5'-BCL2 / IGLlambda junctions involved intronic regions where the normal recombination process does not occur. In the remaining one case, the 5'-BCL2 fused 3' of a Vlambda gene that was upstream of another Vlambda / Jlambda complex carrying a non-producing configuration, indicating that the receptor editing mechanism was likely involved in this rearrangement. Our study revealed heterogeneous anatomy of the 5'-BCL2 / IGs fusion gene leading to transcriptional activation of BCL2, and suggested that the mechanisms underlying the formation of this particular oncogene / IGs recombination are not identical to those of t(14;18).