Chromosomal aberrations in angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma unspecified: A matrix-based CGH approach

Systemic ALK-Negative Anaplastic Large Cell Lymphoma: Insights into Morphologic, Immunophenotypic, Genetic and Molecular Characteristics

Anaplastic large cell lymphoma (ALCL) is a mature T-cell neoplasm characterized by large pleomorphic cells, often with horseshoe- or kidney-shaped nuclei and abundant cytoplasm (hallmark cells), and uniformly strong CD30 expression. Based on ALK expression or ALK rearrangement, ALCL is further classified into ALK-positive (ALK+) and ALK-negative types. This review focuses on the clinicopathologic, immunophenotypic, cytogenetic and molecular features of systemic ALK-negative ALCL. These patients are usually older adults who present with advanced stage disease and often a poor prognosis. ALK-negative ALCL is morphologically indistinguishable from the common pattern of ALK+ ALCL, but some cases show non-common morphology, such as "donut cells", Hodgkin-like features. ALK-negative ALCL is often negative for T-cell antigens (so-called "antigen loss") and in some cases can have a "null" immunophenotype and be confused with other hematopoietic and non-hematopoietic neoplasms. Recurrent genetic/molecular alterations have been identified in systemic ALK-negative ALCL, including rearrangements of DUSP22, TP63, JAK2, FRK, MYC, ROS1 and TYK2; mutations of JAK1, STAT3 and MSCE; and aberrant expression of ERBB4. Some of these alterations may have prognostic significance and/or provide potential therapeutic targets. Data support the idea that ALK-negative ALCL with DUSP22 rearrangement is a distinctive variant due to its unique morphologic, immunophenotypic and molecular features. Gene expression profiling data have shownthat ALK-negative ALCL has distinctive molecular signatures, different from ALK+ ALCL and other T-cell lymphomas. Better understanding of the morphologic, immunophenotypic, genetic and molecular features of ALK-negative ALCL will help establish the correct diagnosis, guide therapeutic strategies and improve patient outcomes.

MYC expression is associated with older age, common morphology, increased MYC copy number, and poorer prognosis in patients with ALK+ anaplastic large cell lymphoma

The role of MYC dysregulation has been studied extensively in B-cell lymphomas, but little is known about its significance in T cell lymphomas. This study, for the first time in the literature, assessed the clinicopathologic and prognostic significance of MYC expression in ALK+ anaplastic large cell lymphoma (ALCL) cases. Using ≥50% as the cutoff value for positive MYC expression by immunohistochemistry, 17 of 46 (37%) cases were MYC+. Patients with MYC+ tumors were older (median age, 39 versus 29 years, p = 0.04) and more often showed a common morphologic pattern (100% versus 69%, p = 0.02), when compared with those with MYC-negative tumors. By fluorescence in situ hybridization analysis, 9 of 31 (29%) cases showed increased MYC copy number, and 1 of 31 (3%) case had an MYC rearrangement, and the remaining 21 (68%) cases showed no MYC aberrations. Among the cases with increased MYC copy number, 5 of 8 (62%) cases showed MYC copy gain and/or amplification and 3 of 8 (38%) had polysomy 8. MYC expression was associated with increased MYC copy number (p = 0.01). MYC expression, but not increased MYC copy number, correlated with shorter overall survival (OS) (p = 0.03). In conclusion, MYC expression identified a distinct group of ALK + ALCL patients with more aggressive behavior and shorter OS. Our data suggest that MYC expression is an adverse prognostic factor and may be useful in stratifying or predicting the prognosis of patients with ALK+ ALCL.

Genetic drivers of oncogenic pathways in molecular subgroups of peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a group of complex clinicopathological entities, often associated with an aggressive clinical course. Angioimmunoblastic T-cell lymphoma (AITL) and PTCL-not otherwise specified (PTCL-NOS) are the 2 most frequent categories, accounting for >50% of PTCLs. Gene expression profiling (GEP) defined molecular signatures for AITL and delineated biological and prognostic subgroups within PTCL-NOS (PTCL-GATA3 and PTCL-TBX21). Genomic copy number (CN) analysis and targeted sequencing of these molecular subgroups revealed unique CN abnormalities (CNAs) and oncogenic pathways, indicating distinct oncogenic evolution. PTCL-GATA3 exhibited greater genomic complexity that was characterized by frequent loss or mutation of tumor suppressor genes targeting the CDKN2A /B-TP53 axis and PTEN-PI3K pathways. Co-occurring gains/amplifications of STAT3 and MYC occurred in PTCL-GATA3. Several CNAs, in particular loss of CDKN2A, exhibited prognostic significance in PTCL-NOS as a single entity and in the PTCL-GATA3 subgroup. The PTCL-TBX21 subgroup had fewer CNAs, primarily targeting cytotoxic effector genes, and was enriched in mutations of genes regulating DNA methylation. CNAs affecting metabolic processes regulating RNA/protein degradation and T-cell receptor signaling were common in both subgroups. AITL showed lower genomic complexity compared with other PTCL entities, with frequent co-occurring gains of chromosome 5 (chr5) and chr21 that were significantly associated with IDH2 ^R172 mutation. CN losses were enriched in genes regulating PI3K-AKT-mTOR signaling in cases without IDH2 mutation. Overall, we demonstrated that novel GEP-defined PTCL subgroups likely evolve by distinct genetic pathways and provided biological rationale for therapies that may be investigated in future clinical trials.

Angioimmunoblastic T-Cell Lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is one of the most common types of T-cell lymphoma, representing about 15-20% of cases of peripheral T-cell lymphoma (PTCL). It is characterized by a unique clinical presentation and distinct pathologic and molecular features. Classes of drugs particularly active in AITL are emerging; however, treatment of relapsed and refractory disease remains a challenge. This chapter reviews the epidemiology, clinical presentation, pathogenesis, diagnosis, and treatment of AITL.

Pterostilbene increases Fas expression in T-lymphoblastic leukemia cell lines

Treatment of acute lymphoblastic leukemia (ALL) has been promising in last decades, but side effects still persist and searching for the least toxic agents continue. Pterostilbene (PTE) is a natural compound with several anti-cancer and anti-oxidant properties. Fas, as a member of death inducing family of tumor necrosis factor (TNF) receptors with an intracellular death domain, can initiate the extrinsic apoptosis signaling pathway. Here after the half maximal inhibitory concentration (IC₅₀) determination in cell lines, we searched for PTE effects on Fas, both in mRNA and surface levels in two ALL cell lines, Jurkat and Molt-4. After harvesting cells in optimum situations, MTS assay was used to determine IC₅₀ concentrations. Real-time polymerase chain reaction (RT-PCR) and flow cytometry were performed for Fas mRNA and surface expression variations after exposure to PTE. The findings showed that PTE decreases cell viability with different extent in two ALL cell lines. In addition to inducing apoptosis, it can increase Fas in both gene and cell surface expression in the same concentrations. Pterostilbene as a natural anti-cancer agent can increase Fas expression both in mRNA and surface levels that results in apoptosis signal transduction improvement which sensitizes cells to apoptosis by immune effector cells. As a result, abnormal cells removal would be more efficiently with the minimum side effects on normal cells.

Recurrent Cytogenetic Abnormalities in Intravascular Large B-Cell Lymphoma

OBJECTIVES

Data characterizing the cytogenetic landscape of intravascular large B-cell lymphoma (ILBCL) are limited. Here, we developed a comprehensive karyotypic data set to identify recurrent cytogenetic abnormalities in ILBCL.

METHODS

Cases of ILBCL with complete cytogenetic analysis were identified from an institutional database and the literature. The combined data were systematically reviewed for the presence of recurrent abnormalities.

RESULTS

Four new cases were identified and combined with 25 karyotypes previously published in the literature. Karyotypes were uniformly complex with a median of 10 aberrations. In total, 72.4% had abnormalities involving chromosome 1, with 31.0% involving rearrangements of 1p13 or 1q21; 58.6% had abnormalities involving chromosome 6, which in almost all cases involved 6q; 34.5% had abnormalities involving chromosome 14, with 27.6% involving rearrangements of 14q32; and 55.2% had abnormalities of chromosome 18, with 37.9% harboring trisomy 18.

CONCLUSIONS

Recurrent cytogenetic abnormalities involving chromosomes 1, 6q, and 18 are present in greater than 50% of ILBCL.

Angioimmunoblastic T-cell lymphoma: the many-faced lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is an uncommon subtype of mature peripheral T-cell lymphoma (PTCL). The history of AITL is much longer and deeper than the literature would suggest given the many names that have preceded it. Advanced-stage disease is common with uncharacteristic laboratory and autoimmune findings that often slow or mask the diagnosis. Significant strides in the immunohistochemical and molecular signature of AITL have brought increased ability to diagnose this uncommon type of PTCL. The 2016 World Health Organization classification of lymphoid neoplasms recently acknowledged the complexity of this diagnosis with the addition of other AITL-like subsets. AITL now resides under the umbrella of nodal T-cell lymphomas with follicular T helper phenotype. Induction strategies continue to focus on increasing complete remission rates that allow more transplant-eligible patients to proceed toward consolidative high-dose therapy and autologous stem cell rescue with improving long-term survival. There are several clinical trials in which recently approved drugs with known activity in AITL are paired with induction regimens with the hope of demonstrating long-term progression-free survival over cyclophosphamide, doxorubicin, vincristine, and prednisone. The treatment of relapsed or refractory AITL remains an unmet need. The spectrum of AITL from diagnosis to treatment is reviewed subsequently in a fashion that may one day lead to personalized treatment approaches in a many-faced disease.

Molecular Pathology: Predictive, Prognostic, and Diagnostic Markers in Lymphoid Neoplasms

Lymphoid neoplasms show great diversity in morphology, immunophenotypic profile, and postulated cells of origin, which also reflects the variety of genetic alterations within this group of tumors. This review discusses many of the currently known genetic alterations in selected mature B-cell and T-cell lymphoid neoplasms, and their significance as diagnostic, prognostic, and therapeutic markers. Given the rapidly increasing number of genetic alterations that have been described in this group of tumors, and that the clinical significance of many is still being studied, this is not an entirely exhaustive review of all of the genetic alterations that have been reported.

Pitfalls and major issues in the histologic diagnosis of peripheral T-cell lymphomas: results of the central review of 573 cases from the T-Cell Project, an international, cooperative study

Peripheral T-cell lymphomas (PTCLs) comprise a heterogeneous group of neoplasms that are derived from post-thymic lymphoid cells at different stages of differentiation with different morphological patterns, phenotypes and clinical presentations. PTCLs are highly diverse, reflecting the diverse cells from which they can originate and are currently sub-classified using World Health Organization (WHO) 2008 criteria. In 2006 the International T-Cell Lymphoma Project launched the T-Cell Project, building on the retrospective study previously carried on by the network, with the aim to prospectively collect accurate data to improve knowledge on this group of lymphomas. Based on previously published reports from International Study Groups it emerged that rendering a correct classification of PTCLs is quite difficult because the relatively low prevalence of these diseases results in a lack of confidence by most pathologists. This is the reason why the T-Cell Project requested the availability of diagnostic material from the initial biopsy of each patient registered in the study in order to have the initial diagnosis centrally reviewed by expert hematopathologists. In the present report the results of the review process performed on 573 cases are presented. Overall, an incorrect diagnosis was centrally recorded in 13.1% cases, including 8.5% cases centrally reclassified with a subtype eligible for the project and 4.6% cases misclassified and found to be disorders other than T-cell lymphomas; 2.1% cases were centrally classified as T-Cell disorders not included in the study population. Thus, the T-Cell Project confirmed the difficulties in providing an accurate classification when a diagnosis of PTCLs is suspected, singled out the major pitfalls that can bias a correct histologic categorization and confirmed that a centralized expert review with the application of adequate diagnostic algorithms is mandatory when dealing with these tumours. Copyright © 2016 John Wiley & Sons, Ltd.

Conserved Molecular Underpinnings and Characterization of a Role for Caveolin-1 in the Tumor Microenvironment of Mature T-Cell Lymphomas

Neoplasms of extra-thymic T-cell origin represent a rare and difficult population characterized by poor clinical outcome, aggressive presentation, and poorly defined molecular characteristics. Much work has been done to gain greater insights into distinguishing features among malignant subtypes, but there also exists a need to identify unifying characteristics to assist in rapid diagnosis and subsequent potential treatment. Herein, we investigated gene expression data of five different mature T-cell lymphoma subtypes (n = 187) and found 21 genes to be up- and down-regulated across all malignancies in comparison to healthy CD4⁺ and CD8⁺ T-cell controls (n = 52). From these results, we sought to characterize a role for caveolin-1 (CAV1), a gene with previous description in the progression of both solid and hematological tumors. Caveolin-1 was upregulated, albeit with a heterogeneous nature, across all mature T-cell lymphoma subtypes, a finding confirmed using immunohistochemical staining on an independent sampling of mature T-cell lymphoma biopsies (n = 65 cases). Further, stratifying malignant samples in accordance with high and low CAV1 expression revealed that higher expression of CAV1 in mature T-cell lymphomas is analogous with an enhanced inflammatory and invasive gene expression profile. Taken together, these results demonstrate a role for CAV1 in the tumor microenvironment of mature T-cell malignancies and point toward potential prognostic implications.

[Molecular pathogenesis of peripheral T-cell lymphoma (1): angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma, not otherwise specified and anaplastic large cell lymphoma]

Peripheral T-cell lymphomas (PTCL) belong to the group of non-Hodgkin lymphoma and particularly that of mature T/NK cells lymphoproliferative neoplasms. The 2008 WHO classification describes different PTCL entities with varying prevalence. With the exception of the histological subtype "ALK positive anaplastic large cell lymphoma", PTCL are characterized by a poor prognosis. The mechanisms underlying the pathogenesis of these lymphomas are not yet fully understood, but development of genomic high-throughput analysis techniques now allows to extensively identify the molecular abnormalities present in tumor cells. This review aims to summarize the current knowledge and recent advances about the molecular events occurring at the origin or during the natural history of main entities of PTCL. It will be published in two parts : the first is focused on the three more frequent entities, angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma, not otherwise specified, and anaplastic large cell lymphoma. The second (which will appear in the november issue) will describe other subtypes less frequent and of poor prognosis : extranodal NK/T-cell lymphoma, nasal type, adult T-cell leukemia/lymphoma, and enteropathy-associated T-cell lymphoma. T or NK cell lymphoproliferative disorders with leukemic presentation, primary cutaneous T-cell lymphoma and very rare subtypes of PTCL whose prevalence is less than 5% (hepatosplenic T-cell lymphoma and subcutaneous panniculitis-like T cell lymphoma) will not be discussed herein.

Methylation-independent repression of Dnmt3b contributes to oncogenic activity of Dnmt3a in mouse MYC-induced T-cell lymphomagenesis

DNA methyltransferase 3A (DNMT3A) catalyzes cytosine methylation of mammalian genomic DNA. In addition to myeloid malignancies, mutations in DNMT3A have been recently reported in T-cell lymphoma and leukemia, implying a possible involvement in the pathogenesis of human diseases. However, the role of Dnmt3a in T-cell transformation in vivo is poorly understood. Here we analyzed the functional consequences of Dnmt3a inactivation in a mouse model of MYC-induced T-cell lymphomagenesis (MTCL). Loss of Dnmt3a delayed tumorigenesis by suppressing cellular proliferation during disease progression. Gene expression profiling and pathway analysis identified upregulation of 17 putative tumor suppressor genes, including DNA methyltransferase Dnmt3b, in Dnmt3a-deficient lymphomas as molecular events potentially responsible for the delayed lymphomagenesis in Dnmt3a(Δ/Δ) mice. Interestingly, promoter and gene body methylation of these genes was not substantially changed between control and Dnmt3a-deficient lymphomas, suggesting that Dnmt3a may inhibit their expression in a methylation-independent manner. Re-expression of both wild type and catalytically inactive Dnmt3a in Dnmt3a(Δ/Δ) lymphoma cells in vitro inhibited Dnmt3b expression, indicating that Dnmt3b upregulation may be directly repressed by Dnmt3a. Importantly, genetic inactivation of Dnmt3b accelerated lymphomagenesis in Dnmt3a(Δ/Δ) mice, demonstrating that upregulation of Dnmt3b is a relevant molecular change in Dnmt3a-deficient lymphomas that inhibits disease progression. Collectively, our data demonstrate an unexpected oncogenic role for Dnmt3a in MTCL through methylation-independent repression of Dnmt3b and possibly other tumor suppressor genes.

STX11 functions as a novel tumor suppressor gene in peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are a heterogeneous group of non-Hodgkin lymphomas with poor prognosis. Their molecular pathogenesis has not been entirely elucidated. We previously showed that 6q24 is one of the most frequently deleted regions in primary thyroid T-cell lymphoma. In this study, we extended the analysis to other subtypes of PTCL and performed functional assays to identify the causative genes of PTCL that are located on 6q24. Genomic loss of 6q24 was observed in 14 of 232 (6%) PTCL cases. The genomic loss regions identified at 6q24 always involved only two known genes, STX11 and UTRN. The expression of STX11, but not UTRN, was substantially lower in PTCL than in normal T-cells. STX11 sequence analysis revealed mutations in two cases (one clinical sample and one T-cell line). We further analyzed the function of STX11 in 14 cell lines belonging to different lineages. STX11 expression only suppressed the proliferation of T-cell lines bearing genomic alterations at the STX11 locus. Interestingly, expression of a novel STX11 mutant (p.Arg78Cys) did not exert suppressive effects on the induced cell lines, suggesting that this mutant is a loss-of-function mutation. In addition, STX11-altered PTCL not otherwise specified cases were characterized by the presence of hemophagocytic syndrome (67% vs 8%, P = 0.04). They also tended to have a poor prognosis compared with those without STX11 alteration. These results suggest that STX11 plays an important role in the pathogenesis of PTCL and they may contribute to the future development of new drugs for the treatment of PTCL.

Changing the paradigms of treatment in peripheral T-cell lymphoma: from biology to clinical practice

Despite enormous advances in our understanding of aggressive lymphomas, it is clear that progress in the peripheral T-cell lymphomas (PTCL) has lagged well behind other B-cell malignancies. Although there are many reasons for this, the one commonly cited notes that the paradigms for diffuse large B-cell lymphoma (DLBCL) were merely applied to all patients with PTCL, the classic "one-size-fits-all" approach. Despite these challenges, progress is being made. Recently, the FDA has approved four drugs for patients with relapsed/refractory PTCL over the past 5 years, and if one counts the recent Japanese approval of the anti-CCR4 monoclonal antibody for patients with adult T-cell leukemia/lymphoma, five drugs have been approved worldwide. These efforts have led to the initiation of no fewer than four randomized clinical studies exploring the integration of these new agents into standard CHOP (cyclophosphamide-Adriamycin-vincristine-prednisone)-based chemotherapy regimens for patients with newly diagnosed PTCL. In addition, a new wave of studies are exploring the merits of novel drug combinations in the disease, an effort to build on the obvious single-agent successes. What has emerged most recently is the recognition that the PTCL may be a disease-characterized by epigenetic dysregulation, which may help explain its sensitivity to histone deacetylase (HDAC) inhibitors, and open the door for even more creative combination approaches. Nonetheless, advances made over a relatively short period of time are changing how we now view these diseases and, hopefully, have poised us to finally improve its prognosis. See all articles in this CCR Focus section, "Paradigm Shifts in Lymphoma."

Pathology of T-cell lymphomas: diagnosis and biomarker discovery

T-cell lymphomas are a group of predominantly rare hematologic malignancies that tend to recapitulate different stages of T-cell development, in a similar way that B-cell lymphomas do. As opposed to B-cell lymphomas, the understanding of the biology and the classification of T-cell lymphomas are somewhat rudimentary, and numerous entities are still included as 'provisional categories' in the World Health Classification of hematolopoietic malignancies. A relevant and useful classification of these disorders have been difficult to accomplish because of the rarity nature of them, the relative lack of understanding of the molecular pathogenesis, and their morphological and immunophenotypical complexity. Overall, T-cell lymphomas represent only 15 % of all non-Hodgkin lymphomas. This review is focused on addressing the current status of the categories of mature T-cell leukemias and lymphomas (nodal and extranodal) using an approach that incorporates histopathology, immunophenotype, and molecular understanding of the nature of these disorders, using the same philosophy of the most recent revised WHO classification of hematopoietic malignancies.

Pathogenetic and diagnostic significance of microRNA deregulation in peripheral T-cell lymphoma not otherwise specified

Peripheral T-cell lymphomas not otherwise specified (PTCLs/NOS) are rare and aggressive tumours whose molecular pathogenesis and diagnosis are still challenging. The microRNA (miRNA) profile of 23 PTCLs/NOS was generated and compared with that of normal T-lymphocytes (CD4+, CD8+, naive, activated). The differentially expressed miRNA signature was compared with the gene expression profile (GEP) of the same neoplasms. The obtained gene patterns were tested in an independent cohort of PTCLs/NOS. The miRNA profile of PTCLs/NOS then was compared with that of 10 angioimmunoblastic T-cell lymphomas (AITLs), 6 anaplastic large-cell lymphomas (ALCLs)/ALK+ and 6 ALCLs/ALK−. Differentially expressed miRNAs were validated in an independent set of 20 PTCLs/NOS, 20 AITLs, 19 ALCLs/ALK− and 15 ALCLs/ALK+. Two hundred and thirty-six miRNAs were found to differentiate PTCLs/NOS from activated T-lymphocytes. To assess which miRNAs impacted on GEP, a multistep analysis was performed, which identified all miRNAs inversely correlated to different potential target genes. One of the most discriminant miRNAs was selected and its expression was found to affect the global GEP of the tumours. Moreover, two sets of miRNAs were identified distinguishing PTCL/NOS from AITL and ALCL/ALK−, respectively. The diagnostic accuracy of this tool was very high (83.54%) and its prognostic value validated.

Increased Expression of Phosphorylated FADD in Anaplastic Large Cell and Other T-Cell Lymphomas

FAS-associated protein with death domain (FADD) is a major adaptor protein involved in extrinsic apoptosis, embryogenesis, and lymphocyte homeostasis. Although abnormalities of the FADD/death receptor apoptotic pathways have been established in tumorigenesis, fewer studies have analyzed the expression and role of phosphorylated FADD (pFADD). Our identification of FADD as a lymphoma-associated autoantigen in T-cell lymphoma patients raises the possibility that pFADD, with its correlation with cell cycle, may possess role(s) in human T-cell lymphoma development. This immunohistochemical study investigated pFADD protein expression in a range of normal tissues and lymphomas, particularly T-cell lymphomas that require improved therapies. Whereas pFADD was expressed only in scattered normal T cells, it was detected at high levels in T-cell lymphomas (eg, 84% anaplastic large cell lymphoma and 65% peripheral T cell lymphomas, not otherwise specified). The increased expression of pFADD supports further study of its clinical relevance and role in lymphomagenesis, highlighting phosphorylation of FADD as a potential therapeutic target.

Gene expression signatures delineate biological and prognostic subgroups in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) encompasses a heterogeneous group of neoplasms with generally poor clinical outcome. Currently 50% of PTCL cases are not classifiable: PTCL-not otherwise specified (NOS). Gene-expression profiles on 372 PTCL cases were analyzed and robust molecular classifiers and oncogenic pathways that reflect the pathobiology of tumor cells and their microenvironment were identified for major PTCL-entities, including 114 angioimmunoblastic T-cell lymphoma (AITL), 31 anaplastic lymphoma kinase (ALK)-positive and 48 ALK-negative anaplastic large cell lymphoma, 14 adult T-cell leukemia/lymphoma and 44 extranodal NK/T-cell lymphoma that were further separated into NK-cell and gdT-cell lymphomas. Thirty-seven percent of morphologically diagnosed PTCL-NOS cases were reclassified into other specific subtypes by molecular signatures. Reexamination, immunohistochemistry, and IDH2 mutation analysis in reclassified cases supported the validity of the reclassification. Two major molecular subgroups can be identified in the remaining PTCL-NOS cases characterized by high expression of either GATA3 (33%; 40/121) or TBX21 (49%; 59/121). The GATA3 subgroup was significantly associated with poor overall survival (P = .01). High expression of cytotoxic gene-signature within the TBX21 subgroup also showed poor clinical outcome (P = .05). In AITL, high expression of several signatures associated with the tumor microenvironment was significantly associated with outcome. A combined prognostic score was predictive of survival in an independent cohort (P = .004).

Challenges and new prospects in hepatosplenic γδ T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of lymphoid neoplasms characterized by aggressive clinical behavior and dismal prognosis. Hepatosplenic γδ T-cell lymphoma (γδ-HSTL) is a particular form of PTCL that arises from a small subset of γ/δ T-cell receptor-expressing lymphocytes. γδ-HSTL has a rapidly progressive course and poor outcome due also to its refractoriness to conventional chemotherapy regimens. The very low incidence of γδ-HSTL, along with its propensity to mimic different pathological entities, makes this lymphoma a true diagnostic challenge. In this review, we highlight the biological and clinical features of γδ-HSTL that contribute to making this lymphoma a mostly incurable disease. Moreover, we provide a new insight into the crosstalk between HSTL clones and the bone marrow, liver and spleen vascular microenvironment, in which neoplastic cells reside and proliferate. We further discuss γδ-HSTL associated molecules that might be proposed as potential targets for novel therapeutic approaches.

Clinical applications of BAC array-CGH to the study of diffuse large B-cell lymphomas

BAC array-CGH is a powerful method to identify DNA copy number changes (gains, amplifications and deletions) on a genome-wide scale, and to map these changes to genomic sequence. It is based on the analysis of genomic DNA isolated from test and reference cell populations, the differential labelling with fluorescent dyes and the co-hybridization with a genomic array. BAC array-CGH has proven to be a specific, sensitive, and reliable technique, with considerable advantages compared to other methods used for the analysis of DNA copy number changes. The application of genome scanning technologies and the recent advances in bioinformatics tools that enable us to perform a robust and highly sensitive analysis of array-CGH data, useful not only for genome scanning of tumor cells but also in the identification of novel cancer related genes, oncogenes and suppressor genes. Cytogenetic analysis provides essential information for diagnosis and prognosis in patients with hematologic malignancies such as lymphomas. However, the chromosomal interpretation in non-Hodgkin lymphoma (NHL) is sometimes inconclusive. Copy number aberrations identified by BAC array-CGH analyses could be a complementary methodology to chromosomal analysis. In NHL the genomic imbalances might have a prognostic rather than a diagnostic value. In fact, the diagnosis of NHL is based on pathological and molecular cytogenetics data. Furthermore genetic variations and their association with specific types of lymphoma development, and elucidation of the variable genetic pathways leading to lymphoma development, are important directions for future cancer research. Array-CGH, along with FISH and PCR, will be used for routine diagnostic purposes in near future.

Follicular T-cell lymphoma: a member of an emerging family of follicular helper T-cell derived T-cell lymphomas

Unlike B-cell lymphomas, where knowledge of normal B-cell origin and differentiation has greatly contributed to their classification, the current classification of peripheral T-cell lymphomas is limited by a lack of understanding of their cellular origin. In the current World Health Organization classification of lymphomas, follicular T-cell lymphoma was formally recognized as a morphologic variant of peripheral T-cell lymphoma, not otherwise specified. There is growing evidence, however, that follicular T-cell lymphoma may be a unique clinicopathologic entity based on its morphologic features and derivation from follicular helper T-cells. In addition, there are abundant recent data supporting the concept that follicular helper T-cells can give rise to other types of T-cell lymphoma, including angioimmunoblastic T-cell lymphoma, primary cutaneous CD4+ small/medium T-cell lymphoma, and a subset of neoplasms, in addition to follicular T-cell lymphoma, currently classified as peripheral T-cell lymphoma, not otherwise specified. In this review, we focus primarily on the clinicopathologic, immunophenotypic, and molecular features of follicular T-cell lymphoma and discuss its potential relationship with other types of T-cell lymphoma thought to be derived from follicular helper T-cells.

Genetic alterations in systemic nodal and extranodal non-cutaneous lymphomas derived from mature T cells and natural killer cells

Mature (peripheral) T-cell and natural killer (NK)-cell lymphomas comprise a series of rather different neoplasms. Based on morphologic, immunophenotypic, genetic, and clinical data, the World Health Organization classification recognizes more than 20 entities or provisional entities. The variable clinical presentations, the objective recognition and pathological stratification, the difficulties regarding treatment, and the hardly predictable response to therapy indicate that the management of these entities requires novel tools. In contrast to B-cell lymphomas or precursor T-cell neoplasms, few recurrent translocations have been identified so far in T-cell non-Hodgkin's and NK-cell lymphomas. Additionally, some of the entities recognized by the World Health Organization classification are very rare and very scarce molecular data are available for T-cell lymphomas. Here, we have reviewed published reports focusing on the genetic lesions and gene expression profiling underlying systemic nodal and extranodal non-cutaneous mature T-cell and NK-cell lymphomas. We also provide a summary of new agents in clinical development and outline some future directions.

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.

Update: peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) are a group of biologically heterogeneous but typically aggressive diseases. Progress in understanding and developing optimal therapies for PTCLs has been hampered by disease rarity and only relatively recent recognition of the importance of the T-cell phenotype. The International Peripheral T-cell Lymphoma Project was a large collaborative effort to provide a broader understanding of prognosis. Recently, several new therapies have shown promise in the treatment of PTCLs.

Tricky and Terrible T-Cell Tumors: These are Thrilling Times for Testing: Molecular Pathology of Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) encompass a group of rare and usually clinically aggressive diseases. The classification and diagnosis of these diseases are compounded by their marked pathological heterogeneity and complex clinical features. With the exception of ALK-positive anaplastic large cell lymphoma (ALCL), which is defined on the basis of ALK rearrangements, genetic features play little role in the definition of other disease entities. In recent years, hitherto unrecognized chromosomal translocations have been reported in small subsets of PTCLs, and genome-wide array-based profiling investigations have provided novel insights into their molecular characteristics. This article summarizes the current knowledge on the best-characterized genetic and molecular alterations underlying the pathogenesis of PTCLs, with a focus on recent discoveries, their relevance to disease classification, and their management implications from a diagnostical and therapeutical perspective.

Pathology and biology of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of more than 20 neoplastic entities derived from mature T cells and natural killer (NK) cells involved in innate and adaptive immunity. With few exceptions these malignancies, which may present as disseminated, predominantly extranodal or cutaneous, or predominantly nodal diseases, are clinically aggressive and have a dismal prognosis. Their diagnosis and classification is hampered by several difficulties, including a significant morphological and immunophenotypic overlap across different entities, and the lack of characteristic genetic alterations for most of them. Although there is increasing evidence that the cell of origin is a major determinant for the delineation of several PTCL entities, however, the cellular derivation of most entities remains poorly characterized and/or may be heterogeneous. The complexity of the biology and pathophysiology of PTCLs has been only partly deciphered. In recent years, novel insights have been gained from genome-wide profiling analyses. In this review, we will summarize the current knowledge on the pathobiological features of peripheral NK/T-cell neoplasms, with a focus on selected disease entities manifesting as tissue infiltrates primarily in extranodal sites and lymph nodes.

Molecular cytogenetics of lymphoma: where do we stand in 2010?

For the past 20 years most malignant lymphomas have been classified as clinicopathological entities, each with its own combination of clinical, morphological, immunophenotypic and molecular genetic characteristics. Molecular and cytogenetic abnormalities can be detected by a wide range of techniques, ranging from conventional karyotyping to single nucleotide polymorphism analysis. In this review, we consider the common genetic abnormalities found in lymphoma and discuss the advantages and disadvantages of individual techniques used in their detection. Finally, we discuss briefly possible novel developments in the field of lymphoma diagnostics.

Refining tumor-associated aneuploidy through 'genomic recoding' of recurrent DNA copy number aberrations in 150 canine non-Hodgkin lymphomas

Identification of the genomic regions most intimately associated with non-Hodgkin lymphoma (NHL) pathogenesis is confounded by the genetic heterogeneity of human populations. We hypothesize that the restricted genetic variation of purebred dogs, combined with the contrasting architecture of the human and canine karyotypes, will increase the penetrance of fundamental NHL-associated chromosomal aberrations in both species. We surveyed non-random aneuploidy in 150 canine NHL cases, revealing limited genomic instability compared to their human counterparts and no evidence for CDKN2A/B deletion in canine B-cell NHL. 'Genomic recoding' of canine NHL data into a 'virtual human' chromosome format showed remarkably few regions of copy number aberration (CNA) shared between both species, restricted to regions of dog chromosomes 13 and 31, and human chromosomes 8 and 21. Our data suggest that gene discovery in NHL may be enhanced through comparative studies exploiting the less complex association between CNAs and tumor pathogenesis in canine patients.

Pathological and immunohistological findings and genetic aberrations of intestinal enteropathy-associated T cell lymphoma in Japan

AIMS

To elucidate the clinicopathological findings of primary intestinal enteropathy-associated T cell lymphoma (EATL) in Japan, a non-endemic area for coeliac disease.

METHODS AND RESULTS

Of the 24 cases, four (17%) had large-cell lymphoma (type I), and the remaining 20 (83%) had medium-sized lymphoma (type II). Lymphoma cells of the three type I cases were CD56-positive. Only one (4%) case showed typical CD56- and CD8-negative and CD30-positive type I EATL. In type II EATL, lymphoma cells of the 16 (80%) and 11 (55%) cases were positive for CD56 and CD8, respectively. Intramucosal tumour spreading and adjacent enteropathy-like lesions were detected in 15 (71%) and 16 (76%) of 21 cases, with a severe increase of intraepithelial lymphocytes (IELs) in 12 (57%). IELs of enteropathy-like lesions in five (24%) cases expressed T-bet, with no cases of CD30-positive IELs. Characteristic findings from comparative genomic hybridization of 15 cases indicated gains of 8q2 (47%), Xp (53%) and Xq (73%), but no gain of 9q3. Regarding, human leucocyte antigen (HLA) status, six cases examined did not express the DQB1*02 allele.

CONCLUSIONS

Japanese EATL exhibited different histology, cytogenetic findings and HLA status from those of typical type I EATL. The rare incidence of coeliac disease may influence the tumour cell characteristics of EATL and IELs.

High resolution SNP array genomic profiling of peripheral T cell lymphomas, not otherwise specified, identifies a subgroup with chromosomal aberrations affecting theRELlocus

Little is known about genomic aberrations in peripheral T cell lymphoma, not otherwise specified (PTCL NOS). We studied 47 PTCL NOS by 250k GeneChip single nucleotide polymorphism arrays and detected genomic imbalances in 22 of the cases. Recurrent gains and losses were identified, including gains of chromosome regions 1q32-43, 2p15-16, 7, 8q24, 11q14-25, 17q11-21 and 21q11-21 (> or = 5 cases each) as well as losses of chromosome regions 1p35-36, 5q33, 6p22, 6q16, 6q21-22, 8p21-23, 9p21, 10p11-12, 10q11-22, 10q25-26, 13q14, 15q24, 16q22, 16q24, 17p11, 17p13 and Xp22 (> or = 4 cases each). Genomic imbalances affected several regions containing members of nuclear factor-kappaB signalling and genes involved in cell cycle control. Gains of 2p15-16 were confirmed in each of three cases analysed by fluorescence in situ hybridization (FISH) and were associated with breakpoints at the REL locus in two of these cases. Three additional cases with gains of the REL locus were detected by FISH among 18 further PTCL NOS. Five of 27 PTCL NOS investigated showed nuclear expression of the REL protein by immunohistochemistry, partly associated with genomic gains of the REL locus. Therefore, in a subgroup of PTCL NOS gains/rearrangements of REL and expression of REL protein may be of pathogenetic relevance.

Array comparative genomic hybridization analysis of PTCL-U reveals a distinct subgroup with genetic alterations similar to lymphoma-type adult T-cell leukemia/lymphoma

PURPOSE

Peripheral T-cell lymphoma, unspecified (PTCL-U) comprises histopathologically and clinically heterogeneous groups. The purpose of this study was to identify subgroups with distinct genetic, histopathologic, and prognostic features.

EXPERIMENTAL DESIGN

We used array comparative genomic hybridization (CGH) for high-resolution analysis of 51 PTCL-U patients and the array data for examining possible correlations of histopathologic and clinical features. Moreover, we compared the genetic, histopathologic, and prognostic features of the PTCL-U cases with those of 59 cases of lymphoma-type adult T-cell leukemia/lymphoma (ATLL).

RESULTS

We identified 32 regions with frequent genomic imbalance, 1 region with high copy number gain at 14q32.2, and 1 region with homozygous loss at 9p21.3. Gains of 7p and 7q and loss of 9p21.3 showed a significant association with poor prognosis. PTCL-U cases with genomic imbalance showed distinct histopathologic and prognostic features compared with such cases without alteration and a marked genetic, histopathologic, and prognostic resemblance to lymphoma-type ATLL.

CONCLUSIONS

The array CGH enabled us to identify the frequently altered genomic regions with strong prognostic power among PTCL-U cases. A correlative analysis using the array CGH data disclosed a subgroup in PTCL-U with genomic alterations and with histopathologic and clinical relevance. In addition to histopathologic similarity, the strong genetic and prognostic resemblance between PTCL-U cases with genomic imbalance detected by array CGH and lymphoma-type ATLL seems to support the notion that the former may constitute a distinct PTCL-U subgroup.

High-resolution analysis of chromosome copy number alterations in angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, unspecified, with single nucleotide polymorphism-typing microarrays

Angioimmunoblastic T-cell lymphoma (AILT) and peripheral T-cell lymphoma, unspecified (PTCL-u) are relatively frequent subtypes of T- or natural killer cell lymphoma. To characterize the structural anomalies of chromosomes associated with these disorders, we here determined chromosome copy number alterations (CNAs) and loss of heterozygosity (LOH) at >55,000 single nucleotide polymorphism loci for clinical specimens of AILT (n=40) or PTCL-u (n=33). Recurrent copy number gain common to both conditions was detected on chromosomes 8, 9 and 19, whereas common LOH was most frequent for a region of chromosome 2. AILT- or PTCL-u-specific CNAs or LOH were also identified at 21 regions, some spanning only a few hundred base pairs. We also identified prognosis-related CNAs or LOH by several approaches, including Cox's proportional hazard analysis. Among the genes that mapped to such loci, a poor prognosis was linked to overexpression of CARMA1 at 7p22 and of MYCBP2 at 13q22, with both genes being localized within regions of frequent copy number gain. For a frequent LOH region at 2q34, we also identified IKAROS family zinc-finger 2 cDNAs encoding truncated proteins. Our data indicate that AILT and PTCL-u consist of heterogeneous subgroups with distinct transforming genetic alterations.

Pathobiology and molecular profiling of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of rare diseases, usually manifesting clinical aggressiveness. Although important novel insights into the pathobiology of nodal PTCL have been gained recently from molecular profiling studies and clinico-pathological analyses, the pathogenetic molecular lesions remain to be deciphered for most entities. Angioimmunoblastic T-cell lymphoma (AITL) comprises CD4+ CXCL13+ neoplastic cells displaying overlapping immunophenotypical and molecular features with normal follicular helper T cells. This derivation might account for the presence of a prominent non-neoplastic component in AITL tissues and the clinical manifestations of the disease reflective of an immunological dysfunction. ALK+ anaplastic large cell lymphoma (ALCL), defined by ALK gene translocation with various gene partners, is composed of CD30+ ALK+ cells with a cytotoxic phenotype and usually carries a good prognosis. ALK- ALCL, now considered as a distinct disease entity, is morphologically and immunophenotypically similar to ALK+ ALCL, except for ALK expression, but has distinctive molecular features. PTCL, not otherwise specified (PTCL, NOS), the largest PTCL category, which is derived from activated CD4+ (or CD8+) T cells, is markedly heterogeneous, including at the molecular level. Gene expression profiling approaches have identified novel biomarkers of potential therapeutic interest, and suggest the existence of molecularly distinct PTCL, NOS subgroups.