Fluorescence in situ hybridization study of chromosome 7 aberrations in hepatosplenic T-cell lymphoma: isochromosome 7q as a common abnormality accumulating in forms with features of cytologic progression

Hepatosplenic T-cell lymphoma in children and adolescents

ABSTRACT

Hepatosplenic T-cell lymphoma (HSTCL) is an aggressive mature T-cell lymphoma characterized by significant hepatosplenomegaly, bone marrow involvement, and minimal or no lymphadenopathy. Primarily affecting young adults, it is exceptionally rare in children and adolescents. This makes diagnosis and treatment particularly challenging for pathologists and pediatric oncologists. Diagnosis typically relies on bone marrow, spleen, or liver biopsy, with histopathologic features including small/medium lymphoid cells with irregular nuclear contours that obstruct the sinuses or sinusoids of the spleen or liver. Immunophenotyping usually reveals CD2/3/7 positivity and CD4/8 negativity, with γδ T-cell receptor rearrangements in most cases. Some genetic distinctions described in pediatric and adolescent patients include chromosome 7 and 8 abnormalities and mutations involving SETD2 and STAT5B. Given the lack of standardized approaches, childhood and adolescent patients with HSTCL are often treated with adult protocols, such as intensive cytotoxic chemotherapy regimens followed by allogeneic hematopoietic stem cell transplantation. Despite these highly intensive treatments, the prognosis for HSTCL remains poor in children and adolescents, with an estimated 5-year overall survival of <15%. HSTCL's rarity in children and adolescents limits accurate epidemiological estimates, clinical experience, data collection, treatment advances, and surveillance recommendations. Data on relapsed/refractory disease are even more limited. This review summarizes known clinical and histopathologic features as well as outcomes specific to children and adolescents with HSTCL, highlighting potential distinctions from adults. We will also discuss future strategies to acquire additional biologic and molecular data, streamline diagnosis, and advance treatment approaches to ultimately improve outcomes for young patients with this deadly disease.

Predictive and prognostic molecular biomarkers in lymphomas

Recent advances in molecular diagnostics have markedly expanded our understanding of the genetic underpinnings of lymphomas and catalysed a transformation in not just how we classify lymphomas, but also how we treat, target, and monitor affected patients. Reflecting these advances, the World Health Organization Classification, International Consensus Classification, and National Comprehensive Cancer Network guidelines were recently updated to better integrate these molecular insights into clinical practice. We summarise here the molecular biomarkers of lymphomas with an emphasis on biomarkers that have well-supported prognostic and predictive utility, as well as emerging biomarkers that show promise for clinical practice. These biomarkers include: (1) diagnostic entity-defining genetic abnormalities [e.g., B-cell acute lymphoblastic leukaemia (B-ALL) with KMT2A rearrangement]; (2) molecular alterations that guide patients' prognoses (e.g., TP53 loss frequently conferring worse prognosis); (3) mutations that serve as the targets of, and often a source of acquired resistance to, small molecular inhibitors (e.g., ABL1 tyrosine kinase inhibitors for B-ALL BCR::ABL1, hindered by ABL1 kinase domain resistance mutations); (4) the growing incorporation of molecular measurable residual disease (MRD) in the management of lymphoma patients (e.g., molecular complete response and sequencing MRD-negative criteria in multiple myeloma). Altogether, our review spans the spectrum of lymphoma types, from the genetically defined subclasses of precursor B-cell lymphomas to the highly heterogeneous categories of small and large cell mature B-cell lymphomas, Hodgkin lymphomas, plasma cell neoplasms, and T/NK-cell lymphomas, and provides an expansive summary of our current understanding of their molecular pathology.

Few and far between: clinical management of rare extranodal subtypes of mature T-cell and NK-cell lymphomas

While all peripheral T-cell lymphomas are uncommon, certain subtypes are truly rare, with less than a few hundred cases per year in the USA. There are often no dedicated clinical trials in these rare subtypes, and data are generally limited to case reports and retrospective case series. Therefore, clinical management is often based on this limited literature and extrapolation of data from the more common, nodal T-cell lymphomas in conjunction with personal experience. Nevertheless, thanks to tremendous pre-clinical efforts to understand these rare diseases, an increasing appreciation of the biological changes that underlie these entities is forming. In this review, we attempt to summarize the relevant literature regarding the initial management of certain rare subtypes, specifically subcutaneous panniculitis-like T-cell lymphoma, hepatosplenic T-cell lymphoma, intestinal T-cell lymphomas, and extranodal NK/T-cell lymphoma. While unequivocally established approaches in these diseases do not exist, we make cautious efforts to provide our approaches to clinical management when possible.

How molecular advances may improve the diagnosis and management of PTCL patients

Peripheral T-cell lymphomas (PTCL) comprised more than 30 rare heterogeneous entities, representing 10 to 15% of adult non-Hodgkin lymphomas. Although their diagnosis is still mainly based on clinical, pathological, and phenotypic features, molecular studies have allowed for a better understanding of the oncogenic mechanisms involved and the refinement of many PTCL entities in the recently updated classifications. The prognosis remains poor for most entities (5-year overall survival < 30%), with current conventional therapies based on anthracyclin-based polychemotherapy regimen, despite many years of clinical trials. The recent use of new targeted therapies appears to be promising for relapsed/refractory patients, such as demethylating agents in T-follicular helper (TFH) PTCL. However further studies are needed to evaluate the proper combination of these drugs in the setting of front-line therapy. In this review, we will summarize the oncogenic events for the main PTCL entities and report the molecular targets that have led to the development of new therapies. We will also discuss the development of innovative high throughput technologies that aid the routine workflow for the histopathological diagnosis and management of PTCL patients.

Extranodal T- and NK-cell lymphomas

Non-cutaneous extranodal NK/T cell lymphoproliferations constitute a heterogenous group of rare neoplasms, occurring primarily in the gastro-intestinal tract, nasal area, spleen, and liver. Their nomenclature refers to their usual clinical presentation and predilection for specific anatomic sites-i.e. extranodal NK/T-cell lymphoma, nasal-type, hepatosplenic T-cell lymphoma, primary intestinal T-cell lymphomas, indolent lymphoproliferative disorders of the gastrointestinal tract, and breast implant-associated anaplastic large cell lymphoma. Extranodal tissues may also be involved by T-cell leukemias, or other entities usually presenting as nodal diseases. Primary extranodal entities range from indolent to highly aggressive diseases. Here, we will review the clinicopathologic features of the pertinent entities including the recent advances in their molecular and genetic characterization, with an emphasis on the changes introduced in the 2022 International Consensus Classification of lymphoid neoplasms, and highlight the diagnostic criteria helpful to sort out the distinction with potential mimickers.

Genomic profiling for clinical decision making in lymphoid neoplasms

With the introduction of large-scale molecular profiling methods and high-throughput sequencing technologies, the genomic features of most lymphoid neoplasms have been characterized at an unprecedented scale. Although the principles for the classification and diagnosis of these disorders, founded on a multidimensional definition of disease entities, have been consolidated over the past 25 years, novel genomic data have markedly enhanced our understanding of lymphomagenesis and enriched the description of disease entities at the molecular level. Yet, the current diagnosis of lymphoid tumors is largely based on morphological assessment and immunophenotyping, with only few entities being defined by genomic criteria. This paper, which accompanies the International Consensus Classification of mature lymphoid neoplasms, will address how established assays and newly developed technologies for molecular testing already complement clinical diagnoses and provide a novel lens on disease classification. More specifically, their contributions to diagnosis refinement, risk stratification, and therapy prediction will be considered for the main categories of lymphoid neoplasms. The potential of whole-genome sequencing, circulating tumor DNA analyses, single-cell analyses, and epigenetic profiling will be discussed because these will likely become important future tools for implementing precision medicine approaches in clinical decision making for patients with lymphoid malignancies.

Update on Pediatric and Young Adult Mature Lymphomas

After acute leukemia and brain and central nervous system tumors, mature lymphomas represent the third most common cancer in pediatric patients. Non-Hodgkin lymphoma accounts for approximately 60% of lymphoma diagnoses in children, with the remainder representing Hodgkin lymphoma. Among non-Hodgkin lymphomas in pediatric patients, aggressive lymphomas, such as Burkitt lymphoma, diffuse large B-cell lymphoma, and anaplastic large cell lymphoma, predominate. This article summarizes the epidemiologic, histopathologic, and molecular features of selected mature systemic B-cell and T-cell lymphomas encountered in this age group.

Pediatric hematolymphoid pathology in the gastrointestinal tract

Hematolymphoid processes involving the gastrointestinal tract in the pediatric and adolescent young adult (AYA) populations include processes occurring primarily within the gastrointestinal tract as well as systemic diseases with predilection for gastrointestinal involvement. Here, we present a focused review of reactive and neoplastic entities occurring in the pediatric and AYA age groups.

Hepatosplenic T-cell lymphoma: a rare but challenging entity

Hepatosplenic T-cell lymphoma (HSTCL) is a rare T-cell neoplasm that most commonly arises from a small subset of γ/δ T-cell receptor-expressing lymphocytes. HSTCL is more common in adolescent and young adults and has a rapidly progressive clinical course and poor outcome due to its refractoriness to conventional chemotherapy regimens. Approximately 20% of the cases arise in the background of chronic immunosuppression or immune dysregulation. Patients commonly present with constitutional symptoms, hepatic and liver enlargement, and cytopenias; hematophagocytic syndrome can also occur. The most frequent chromosomal aberrations associated with HSTCL are isochromosome 7q and trisomy 8, and most cases harbor mutations in genes involved in chromatin modification or the JAK/STAT pathway. The rarity of this disease, along with lack of nodal involvement and presenting symptoms that mimic different entities including infectious etiologies, makes this lymphoma a significant diagnostic challenge. In this review, we highlight the clinical and pathologic features of HSTCL. Moreover, we summarize the results of recent molecular studies suggesting potential targets for novel therapeutics strategies.

NCCN Guidelines Insights: T-Cell Lymphomas, Version 1.2021

Hepatosplenic T-cell lymphoma (HSTCL) is a rare subtype of T-cell lymphoma associated with an aggressive clinical course and a worse prognosis. HSTCL develops in the setting of chronic immune suppression or immune dysregulation in up to 20% of cases and is most often characterized by spleen, liver, and bone marrow involvement. Diagnosis and management of HSTCL pose significant challenges given the rarity of the disease along with the absence of lymphadenopathy and poor outcome with conventional chemotherapy regimens. These Guidelines Insights focus on the diagnosis and treatment of HSTCL as outlined in the NCCN Guidelines for T-Cell Lymphomas.

Hepatosplenic T-Cell Lymphoma in an Immunocompetent Young Male: A Challenging Diagnosis

Hepatosplenic T-cell lymphoma is a rare but highly aggressive form of T-cell malignancy. As cases are not routinely seen in practice, the malignancy can be confused with other hematologic conditions that have a similar presentation. Here in, we present the challenges faced in diagnosing a 27-year-old-male who initially presented with asymptomatic pancytopenia and then developed massive splenomegaly over the next three months. After an elaborate workup, including a bone marrow biopsy and extensive serological testing, which all turned out to be negative, he eventually underwent a splenectomy with biopsy results confirming hepatosplenic T-cell lymphoma.

Hepatosplenic T-Cell Lymphomas

Hepatosplenic T-cell lymphoma (HSTL) is a rare variant of extranodal peripheral T-cell lymphomas (PTCL), associated with aggressive disease course and a relentless track record for lethal outcomes. HSTL presents commonly in young men in their third or fourth decade. Of the known causes, immune dysregulation and immunosuppression are the key players in the pathogenesis of HSTL. Clinical manifestation includes hepatosplenomegaly, fevers, and weakness. Bone marrow involvement or organomegaly can cause cytopenias. Anthracycline-based regimens provide modest responses with most individuals dying within a year of diagnosis. Hematopoietic stem cell transplant (HSCT) can be offered to fit and eligible patients to prolong remissions. Disease relapse post chemotherapy has an aggressive phenotype, with limited salvage options available in the setting of declining performance status. Understanding the disease biology further to identify mechanistic-driven drug discovery could overcome the current limitations of existing therapeutic armamentarium.

A rare case of hepatosplenic γδ T-cell lymphoma expressing CD19 with ring chromosome 7 and trisomy 8

Hepatosplenic T-cell lymphoma (HSTL) is a rare subtype of peripheral T-cell lymphoma predominantly seen in young males. This disease presents with isolated hepatosplenomegaly and thrombocytopenia with sinusoidal infiltration of liver and sinusal infiltration of spleen. Immunophenotype shows positivity for CD3, CD7, TCRγδ or TCRαβ, CD38 and double negative for CD4, CD8, TdT, CD5, and CD56. Isochromosome 7q with or without trisomy 8 is seen in HSTL. Recently, ring chromosome 7 has also been identified as a new abnormality. We describe the clinical, immunophenotypic and cytogenetic analysis in a 24-year-old woman. We present an unusual case of TCRγδ positive T-cell lymphoma with aberrant expression of CD19, which is a B-cell lymphoid marker, with amplification of 7q region and subsequent formation of ring chromosome 7 and trisomy 8. This is the second case of HSTL, positive for CD19 and first case presenting with ring chromosome 7 and trisomy 8 in a CD19 positive HSTL which is a rare finding in T-cell lymphoma and needs to be explored further.

The Diagnosis, Management, and Role of Hematopoietic Stem Cell Transplantation in Aggressive Peripheral T-Cell Neoplasms

Background

Peripheral T-cell neoplasms (PTCNs) comprise a group of uncommon and heterogeneous lymphoid malignancies. They are more difficult to diagnose and treat and have a worse prognosis than B-cell lymphomas. Although PTCNs initially show a significant degree of chemosensitivity, the outcome of treatment with conventional dose chemotherapy remains poor.

Methods

We reviewed the literature on the diagnosis, treatment, and collective transplant reports regarding PTCNs.

Results

The correct diagnosis of peripheral T-cell lymphoma requires a combination of clinical presentation, morphology, immunophenotype, and molecular study. While no specific treatment other than conventional dose chemotherapy is currently available for aggressive PTCN, histone acetylase inhibitors and monoclonal antibodies such as anti-CD7 and anti-CD52 are being studied in T-cell malignancies. The role of autologous and allogeneic transplantation is being investigated for high-risk, relapsed, and refractory PTCNs with some promising results.

Conclusions

Access to hematopathology expertise in a tertiary care setting may lead to earlier and more accurate diagnoses of these diseases. PTCNs comprise a heterogeneous group of diseases with no widely accepted standard of care, and accurate determination of their histologic subtypes correlates with prognosis. Patients in first complete remission with poor risk features and patients with relapsed and refractory disease should be considered for bone marrow transplant due to the poor outcomes obtained with conventional chemotherapy.

The Genetic Basis of Hepatosplenic T-cell Lymphoma

Hepatosplenic T-cell lymphoma (HSTL) is a rare and lethal lymphoma; the genetic drivers of this disease are unknown. Through whole-exome sequencing of 68 HSTLs, we define recurrently mutated driver genes and copy-number alterations in the disease. Chromatin-modifying genes, including SETD2, INO80, and ARID1B, were commonly mutated in HSTL, affecting 62% of cases. HSTLs manifest frequent mutations in STAT5B (31%), STAT3 (9%), and PIK3CD (9%), for which there currently exist potential targeted therapies. In addition, we noted less frequent events in EZH2, KRAS, and TP53SETD2 was the most frequently silenced gene in HSTL. We experimentally demonstrated that SETD2 acts as a tumor suppressor gene. In addition, we found that mutations in STAT5B and PIK3CD activate critical signaling pathways important to cell survival in HSTL. Our work thus defines the genetic landscape of HSTL and implicates gene mutations linked to HSTL pathogenesis and potential treatment targets.Significance: We report the first systematic application of whole-exome sequencing to define the genetic basis of HSTL, a rare but lethal disease. Our work defines SETD2 as a tumor suppressor gene in HSTL and implicates genes including INO80 and PIK3CD in the disease. Cancer Discov; 7(4); 369-79. ©2017 AACR.See related commentary by Yoshida and Weinstock, p. 352This article is highlighted in the In This Issue feature, p. 339.

Recurrent Cytogenetic Abnormalities in Non-Hodgkin's Lymphoma and Chronic Lymphocytic Leukemia

Characteristic chromosomal translocations are found to be associated with subtypes of B-cell non-Hodgkin lymphoma (NHL), for example t(8;14)(q24;q32) and Burkitt lymphoma, t(14;18)(q32;q21) and follicular lymphoma, and t(11;14)(q13;q32) in mantle cell lymphoma. Only few recurrent cytogenetic aberrations have been identified in the T-cell NHL and the best known is the ALK gene translocation t(2;5)(p23;q35) in anaplastic large cell lymphoma. Since lymph node or other tissue is seldom submitted for conventional cytogenetics study, alternative approaches for translocation detection are polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH). FISH is more sensitive than PCR in the detection of lymphoma translocations since directly labeled large FISH probes that span the translocation breakpoints are used. Although the recurrent chromosomal abnormalities in NHL are not completely sensitive and specific for disease entities, unlike the scenario in acute leukemia, cytogenetic and molecular genetic study is commonly used to aid lymphoma diagnosis and classification. Currently, the main clinical utility is in the employment of interphase FISH panels to predict disease aggressiveness to guide therapy, for example identification of double-hit lymphoma, or in prognostication, for example risk-stratification in chronic lymphocytic leukemia. The recent application of high-throughput sequencing to NHL not only advances the understanding of disease pathogenesis and classification, but allows the discovery of new drug targets, such as BRAF gene inhibition in hairy cell leukemia. Coupled with the increasing availability of novel molecular targeted therapeutic agents, the hope for the future is to translate the genetics and genomics information to achieve personalized medicine in NHL.

Hepatosplenic T-cell lymphoma in a young immunocompetent man

Hepatosplenic T-cell lymphoma (HSTCL) is a rare, aggressive type of peripheral T-cell lymphoma that is characterised by extranodal disease, with infiltration and proliferation of malignant T-cells within the liver, spleen and bone marrow. The authors report the case of a young immunocompetent man, who was admitted to the hospital with a history of prolonged, unexplained fever, fatigue and weight loss. Initial blood work showed mild pancytopaenia and imaging studies revealed hepatosplenomegaly. The diagnosis was challenging, initially mimicking infectious disease, and it required an extensive investigation that ultimately revealed the characteristic clinical, histopathological and cytogenetic features of HSTCL. The clinical course was aggressive, and despite multiagent chemotherapy, the patient died 4 months after the diagnosis. This case highlights the difficulty of diagnosing HSTCL and the importance of considering it in a differential diagnosis of hepatosplenomegaly in young men who present with constitutional symptoms and no lymphadenopathy.

Hepatosplenic T-Cell Lymphoma: A Clinicopathologic Review With an Emphasis on Diagnostic Differentiation From Other T-Cell/Natural Killer-Cell Neoplasms

Hepatosplenic T-cell lymphoma is a rare, aggressive T-cell lymphoma, characterized by hepatosplenic sinusoidal infiltration of monotonous, medium-sized, nonactivated cytotoxic T cells, usually of γ/δ T-cell receptor type. Hepatosplenic T-cell lymphoma occurs more frequently in immunocompromised patients, especially in those receiving long-term immunosuppressive therapy. Patients usually manifest hepatosplenomegaly without lymphadenopathy. The bone marrow is also involved in two-thirds of cases and is often accompanied by circulating lymphoma cells, which, along with anemia and thrombocytopenia, may raise suspicion for acute leukemia. The differential diagnosis includes aggressive natural killer-cell leukemia, T-large granular lymphocytic leukemia, T-lymphoblastic leukemia, enteropathy-associated T-cell lymphoma type II, primary cutaneous γ/δ T-cell lymphoma, other peripheral T-cell lymphomas, myelodysplastic syndrome, and infectious mononucleosis. The diagnosis is usually established from the combination of clinical findings, histologic features, and immunophenotype, although cytogenetic/molecular studies are occasionally needed. Hepatosplenic T-cell lymphoma exhibits a dismal clinical course with a poor response to currently available therapies.

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.

Gamma-delta t-cell lymphomas

Gamma-delta T-cell lymphomas are aggressive and rare diseases originating from gamma-delta lymphocytes. These cells, which naturally play a role in the innate, non-specific immune response, develop from thymic precursor in the bone marrow, lack the major histocompatibility complex restrictions and can be divided into two subpopulations: Vdelta1, mostly represented in the intestine, and Vdelta2, prevalently located in the skin, tonsils and lymph nodes. Chronic immunosuppression such as in solid organ transplanted subjects and prolonged antigenic exposure are probably the strongest risk factors for the triggering of lymphomagenesis. Two entities are recognised by the 2008 WHO Classification: hepatosplenic gamma-delta T-cell lymphoma (HSGDTL) and primary cutaneous gamma-delta T-cell lymphoma (PCGDTL). The former is more common among young males, presenting with B symptoms, splenomegaly and thrombocytopenia, usually with the absence of nodal involvement. Natural behaviour of HSGDTL is characterised by low response rates, poor treatment tolerability, common early progression of disease and disappointing survival figures. PCGDTL accounts for <1% of all primary cutaneous lymphomas, occurring in adults with relevant comorbidities. Cutaneous lesions may vary, but its clinical behaviour is usually aggressive and long-term survival is anecdotal. Available literature on gamma-delta T-cell lymphomas is fractioned, mostly consisting of case reports or small cumulative series. Therefore, clinical suspicion and diagnosis are usually delayed, and therapeutic management remains to be established. This review critically analyses available evidence on diagnosis, staging and behaviour of gamma-delta T-cell lymphomas, provides recommendations for therapeutic management in routine practice and discusses relevant unmet clinical needs for future studies.

Integrative genomic and transcriptomic analysis identified candidate genes implicated in the pathogenesis of hepatosplenic T-cell lymphoma

Hepatosplenic T-cell lymphoma (HSTL) is an aggressive lymphoma cytogenetically characterized by isochromosome 7q [i(7)(q10)], of which the molecular consequences remain unknown. We report here results of an integrative genomic and transcriptomic (expression microarray and RNA-sequencing) study of six i(7)(q10)-positive HSTL cases, including HSTL-derived cell line (DERL-2), and three cases with ring 7 [r(7)], the recently identified rare variant aberration. Using high resolution array CGH, we profiled all cases and mapped the common deleted region (CDR) at 7p22.1p14.1 (34.88 Mb; 3506316-38406226 bp) and the common gained region (CGR) at 7q22.11q31.1 (38.77 Mb; 86259620–124892276 bp). Interestingly, CDR spans a smaller region of 13 Mb (86259620–99271246 bp) constantly amplified in cases with r(7). In addition, we found that TCRG (7p14.1) and TCRB (7q32) are involved in formation of r(7), which seems to be a byproduct of illegitimate somatic rearrangement of both loci. Further transcriptomic analysis has not identified any CDR-related candidate tumor suppressor gene. Instead, loss of 7p22.1p14.1 correlated with an enhanced expression of CHN2 (7p14.1) and the encoded β2-chimerin. Gain and amplification of 7q22.11q31.1 are associated with an increased expression of several genes postulated to be implicated in cancer, including RUNDC3B, PPP1R9A and ABCB1, a known multidrug resistance gene. RNA-sequencing did not identify any disease-defining mutation or gene fusion. Thus, chromosome 7 imbalances remain the only driver events detected in this tumor. We hypothesize that the Δ7p22.1p14.1-associated enhanced expression of CHN2/β2-chimerin leads to downmodulation of the NFAT pathway and a proliferative response, while upregulation of the CGR-related genes provides growth advantage for neoplastic δγT-cells and underlies their intrinsic chemoresistance. Finally, our study confirms the previously described gene expression profile of HSTL and identifies a set of 24 genes, including three located on chromosome 7 (CHN2, ABCB1 and PPP1R9A), distinguishing HSTL from other malignancies.

Hepatosplenic γδ T-cell lymphoma: an overview

Peripheral T-cell lymphomas are a heterogeneous group of lymphoid malignancies. Among these, hepatosplenic γδ T-cell lymphoma (HTCL) represents an aggressive and treatment-resistant subgroup for which new avenues of treatment are critically needed. HTCL is characterized by primary extranodal distribution of the malignant cells with typical intrasinusoidal infiltration of the liver, spleen, and bone marrow, which results in hepatosplenomegaly and peripheral blood cytopenias. Another characteristic feature is the expression of γδ T-cell receptors. HTCL exhibits a rapid progressive course and an extremely poor response to currently known therapeutic strategies, with a 5-year overall survival rate of only 7%. In this review, we discuss the clinical, pathologic, and molecular characteristics of this disease, along with the challenges that are associated with its diagnosis and treatment.

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.

Detailed clinicopathological characteristics and possible lymphomagenesis of type II intestinal enteropathy-associated T-cell lymphoma in Japan

Twenty-six Japanese cases of type II enteropathy-associated T-cell lymphoma (EATL) were examined. Multiple tumors throughout the small intestine were found in 15 patients (58%) and duodenal and colonic mucosal lesions in 8 and 6 cases, respectively. Histologically, intramucosal tumor spread and a zone of neoplastic intraepithelial lymphocytes (IELs) neighboring the main transmural tumors were detected in 20 (91%) and 17 (77%) of the 22 cases examined, respectively. Inside and outside the IEL zone, some degree of enteropathy with many reactive small IELs and villous atrophy was detected in 11 cases (50%). Immunohistologically, many CD56/CD8-positive small IELs were found in the enteropathic lesions of 4 (36%) and 7 (64%) of these 11 cases. Lymphoma cells expressed tyrosine kinase receptor c-Met, serial phosphorylated (p)-mitogen-activated protein kinase/extracellular signal-regulated kinase, c-Myc, and Bcl2 in 18 (78%), 21 (91%), 11 (42%), and 19 (73%) of the total cases, respectively. By fluorescence in situ hybridization, chromosomal loci 7q31 (c-Met) and 8q24 (c-Myc) were amplified in 11 (65%) and 12 (71%) of the 17 cases analyzed. Gain of 7q31 and c-Met expression were significantly (P < .01) higher than in peripheral CD8-positive T-cell or CD56-positive natural killer-cell lymphomas. Enteropathy was seen near the IEL zone in type II EATL, and activation of the c-Met, mitogen-activated protein kinase/extracellular signal-regulated kinase-mitogen-activated protein kinase pathway, and c-Myc-Bcl2-mediated cell survival may play important roles in lymphomagenesis, converting enteropathy to type II EATL. Seven cases in the early clinical stages I and II-1 showed significantly (P < .01) better prognoses than did those in the advanced stages. Early detection of the mucosal lesions and tumors may improve patient prognosis.

Molecular diagnostics of T-cell lymphoproliferative disorders

T-cell neoplasms include both mature T-cell leukemias and lymphomas and immature proliferations of precursor T cells. Molecular laboratories routinely assay suspected T-cell proliferations for evidence of clonality. In addition, some T-cell neoplasms are characterized by recurrent structural abnormalities that can be readily identified by such techniques as fluorescence in situ hybridization. New massively parallel sequencing technologies have led to the identification of numerous recurrent gene mutations in T-cell neoplasms. These findings are reviewed. As new technologies become implemented in molecular diagnostic laboratories and as targeted therapies are developed, it is anticipated that more extensive genomic characterization of T-cell neoplasms will be routinely performed in the future.

Combating the epigenome: epigenetic drugs against non-Hodgkin's lymphoma

Non-Hodgkin's lymphomas (NHLs) comprise a large and diverse group of neoplasms of lymphocyte origin with heterogeneous molecular features and clinical manifestations. Current therapies are based on standard chemotherapy, immunotherapy, radiation or stem cell transplantation. The discovery of recurrent mutations in epigenetic enzymes, such as chromatin modifiers and DNA methyltransferases, has provided researchers with a rationale to develop novel inhibitors targeting these enzymes. Several clinical and preclinical studies have demonstrated the efficacy of epigenetic drugs in NHL therapy and a few specific inhibitors have already been approved for clinical use. Here, we provide an overview of current NHL classification and a review of the present literature describing epigenetic alterations in NHL, including a summary of different epigenetic drugs, and their use in preclinical and clinical studies.

Mycosis fungoides and Sézary syndrome

The development of array comparative genomic hybridization (aCGH) techniques has allowed to characterize more precisely several human neoplasms with the aim of providing prognostic markers and targets for directed therapeutic intervention. Recently, several studies applying aCGH technique have been reported in which an exhaustive genetic characterization of mycosis fungoides (MF) and Sézary syndrome (SS) has been performed. Regarding MF, a genomic profile characterized by the gains of 7q, 17q, and 8q and losses in 9p, 13q, 17p, and 10q has been described. In SS, the most common abnormalities are gains in 8q and 17q and losses at 17p and 10q. One of the main contributions of the aCGH studies in MF and SS has been the description of genetic markers associated with a poor prognosis. In MF, three specific chromosomal regions, 9p21.3 (CDKN2A, CDKN2B, and MTAP), 8q24.21 (MYC), and 10q26qter (MGMT and EBF3) have been defined as prognostic markers exhibiting a significant correlation with overall survival (P = 0.042, P = 0.017, and P = 0.022, respectively). Moreover, two MF genomic subgroups have been described, distinguishing a stable group (0-5 DNA aberrations) and an unstable group (>5 DNA aberrations), showing that the genomic unstable group had a shorter overall survival (P = 0.05).

A novel cytogenetic abnormality t(7;8)(p11.2:q11.2) and a four-way Philadelphia translocation in an imatinib mesylate-resistant chronic myeloid leukemia patient

Chronic myelogenous leukemia (CML) is characterized by the Philadelphia (Ph) chromosome, created by a reciprocal translocation t(9:22)(q34;q11) which forms the chimeric gene, BCR-ABL. Variant Ph chromosome translocations involving chromosomes other than 9 and 22 have been identified in 5–10% of CML cases. Four-way Ph chromosome translocations are an extremely rare event in myeloid malignancies and the phenotypic consequences of such rearrangements have not been investigated. Deletions in chromosome 9 are known to be associated with a poor prognosis. In the present study, a novel case of Ph chromosome-positive CML in blast crisis is reported. A four-way Ph translocation was identified, involving five chromosomal regions, 9p21, 9q34, 12p13.3, 20q11.2 and 22q11.2, as well as an unbalanced translocation, der(7)t(7;8)(p11.2;q11.2). Since the majority of CML cases are currently treated with imatinib, variant rearrangements in general have no specific prognostic significance, although the mechanisms involved in resistance to therapy have yet to be investigated. In the present case, multiple partial deletions, including ABL and ASS genes on chromosome 9, the region 7p11.2 to 7pter, 8q11.2 to 8pter and two regions on chromosome 12, were identified. An additional Ph chromosome was also detected. Immunophenotyping indicated that the patient had biphenotypic leukemia. The patient did not respond positively to imatinib chemotherapy and died for unknown reasons, one month after diagnosis. The underlying mechanisms and prognostic implications of these cytogenetic abnormalities are discussed.

Intensive induction chemotherapy followed by early high-dose therapy and hematopoietic stem cell transplantation results in improved outcome for patients with hepatosplenic T-cell lymphoma: a single institution experience

INTRODUCTION

Hepatosplenic T-cell lymphoma is a rare form of extranodal non-Hodgkin lymphoma, first recognized as a distinct entity in the Revised European-American Lymphoma classification. Typical presentation includes lymphomatous infiltration of spleen and liver, and peripheral lymphadenopathy is rarely seen. The prognosis is almost uniformly poor, and there are no prospective studies of treatment of HSTCL.

PATIENTS AND METHODS

For this report, we conducted a retrospective review of all pts who underwent treatment for HSTCL at our institution. Individual chart review was performed to report clinical presentation, management, and outcome.

RESULTS

We identified 14 pts with HSTCL managed at our center, 7 of which remain alive with median follow-up of 65.6 months. Six of 7 received alternative induction chemotherapy regimens such as ICE (ifosfamide, carboplatin, etoposide) or IVAC (ifosfamide, etoposide, high-dose cytarabine) as opposed to CHOP and all surviving pts had proceeded to undergo either autologous or allogeneic SCT.

CONCLUSION

Our results suggest that use of non-CHOP induction regimen and early use of high dose therapy and SCT consolidation may translate to improved survival for pts with HSTCL.

Molecular features of hepatosplenic T-cell lymphoma unravels potential novel therapeutic targets

The pathogenesis of hepatosplenic T-cell lymphoma (HSTL), a rare entity mostly derived from γδ T cells and usually with a fatal outcome, remains largely unknown. In this study, HSTL samples (7γδ and 2αβ) and the DERL2 HSTL cell line were subjected to combined gene-expression profiling and array-based comparative genomic hybridization. Compared with other T-cell lymphomas, HSTL had a distinct molecular signature irrespective of TCR cell lineage. Compared with peripheral T-cell lymphoma, not otherwise specified and normal γδ T cells, HSTL overexpressed genes encoding NK-cell-associated molecules, oncogenes (FOS and VAV3), the sphingosine-1-phosphatase receptor 5 involved in cell trafficking, and the tyrosine kinase SYK, whereas the tumor-suppressor gene AIM1 (absent in melanoma 1) was among the most down-expressed. We found highly methylated CpG islands of AIM1 in DERL2 cells, and decitabine treatment induced a significant increase in AIM1 transcripts. Syk was present in HSTL cells and DERL2 cells contained phosphorylated Syk and were sensitive to a Syk inhibitor in vitro. Genomic profiles confirmed recurrent isochromosome 7q (n = 6/9) without alterations at the SYK and AIM1 loci. Our results identify a distinct molecular signature for HSTL and highlight oncogenic pathways that offer rationale for exploring new therapeutic options such as Syk inhibitors and demethylating agents.

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.

Hepatosplenic gamma-delta T-cell lymphoma

Hepatosplenic T-cell lymphoma (HSTL) is a rare and aggressive extranodal lymphoma derived mostly from cytotoxic γδ T-cells. The peak incidence is in adolescents and young adults, and is more common in males. Up to 20% of HSTL arise in the setting of chronic immune suppression, most commonly solid organ transplantation or prolonged antigenic stimulation. Patients present with systemic symptoms (fever), abdominal pain, weakness, and marked hepatosplenomegaly in the absence of lymphadenopathy. Patients usually manifest marked thrombocytopenia, often with anaemia and leucopenia, a leukemic phase, and bone marrow involvement in 80% of cases. Lactate dehydrogenase levels are usually markedly elevated. HSTL exhibits a marked chemoresistance to currently used regimens, a rapidly progressive behavior, and dismal prognosis. Patients with post-transplant HSTL exhibit an especially poor outcome. Standard treatment has yet to be established. Anthracycline-based chemotherapy is associated with a satisfactory response in two thirds of patients, but poor long-term results. Complete remission is extremely uncommon, and most patients die from lymphoma within two years of diagnosis. A prognostic correlation between outcome and degree of thrombocytopenia has been reported. Relapsing disease is usually chemorefractory and fast growing, and patients' performance status and clinical conditions are poor. These aspects, as well as the lack of drugs with proven activity against HSTL, render salvage treatment almost impossible. A few cases of HSTL successfully treated with autologous or allogeneic stem-cell transplantation have been reported. The use of 2'-deoxycoformycin and other targeted therapies, such as alemtuzumab, anti-γδ TCR monoclonal antibodies, and anti-CD44 therapy, have shown promising results in anecdotal reports.

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.

Cytogenetic and molecular characterization of a hepatosplenic T-cell lymphoma: report of a novel chromosomal aberration

Hepatosplenic T-cell lymphomas (HSTCL) are rare cancers and comprise 5% of peripheral T-cell lymphomas. These well-characterized extranodal lymphomas have a disguised onset, secondary to intrasinusoidal infiltration of the spleen, liver, and bone marrow, with a rapidly progressive course that is poorly responsive to chemotherapy and often ensues in the setting of immune system suppression. We describe the clinical, immunophenotypic, cytogenetic, fluorescence in situ hybridization, and molecular analyses for T cell receptor gene rearrangement in a 21-year-old man diagnosed with HSTCL. Immunophenotypic analysis revealed negativity for CD5 as well as double negativity for CD4/CD8 mature T-cell immunophenotype, which suggested the diagnosis of hepatosplenic T-cell lymphoma. Molecular analysis confirmed a TCR gene rearrangement, thereby verifying the common T-cell origin of the present HSTCL case. Furthermore, cytogenetic analysis revealed a novel chromosomal rearrangement, t(7;15)(p22;q21). Metaphase fluorescence in situ hybridization analysis confirmed the translocation of a chromosomal segment from 15q21 to 7p22.

Hepatosplenic T-cell lymphoma and inflammatory bowel disease

OBJECTIVE

This article reviews the current literature and knowledge about hepatosplenic T-cell lymphoma (HSTCL), providing an overview of the clinical features, a description of its pathology and immunophenotypic traits in relation to other lymphomas. In addition, we explore the history of reported cases of hepatosplenic T-cell lymphoma in relation to the possible existence of a causal relationship between infliximab use and HSTCL. The treatments for HSTCL will be briefly addressed.

METHODS

A comprehensive literature search using multiple databases was performed. Keyword search phrases including "lymphoma," "hepatosplenic T-cell lymphoma," "Inflammatory bowel disease," "6-mercaptopurine," and "infliximab" were used in various combinations. In addition references from published papers were reviewed as well.

RESULTS

There are over 200 reported cases of HSTCL. Only 22 cases of hepatosplenic T-cell lymphoma are associated with IBD treatment. Clinicians usually reserve immunomodulators and biologics for moderate to severe IBD cases. The ultimate goal of therapy is to control inflammation and therefore allow mucosal healing. IBD patients demonstrating mucosal healing are less likely to undergo surgery and experience complications related to their disease. We manipulate the immune system with corticosteroids, immunomodulators, and biologics, therefore causing bone marrow suppression. With bone marrow suppression, malignant degeneration may begin through selective uncontrolled cell proliferation, initiating HSTCL development in the genetically susceptible.

CONCLUSION

Hepatosplenic T-cell lymphoma is a rare disease, often with a poor outcome. With the increasing number of reported cases of HSTCL linked to the use of infliximab, adalimumab, and AZA/6-MP, there appears to be an undeniable association of HSTCL development with the use of these agents. This risk is unquantifiable. When considering the rarity of cases and the multiple complications with uncontrolled disease, however, the benefit of treatment far outweighs the risk.

Gamma-delta T-cell lymphomas

Peripheral T-cell lymphomas (TCLs) are uncommon neoplasms, accounting for about 12% of all lymphoid tumors worldwide. TCLs in which gammadelta T-cell receptors are expressed (gammadelta TCLs) are extremely aggressive and rare (<1% of lymphoid neoplasms). gammadelta TCLs originate from gammadelta T cells, a small subset of peripheral T cells with direct antigen recognition capability acting at the interface between innate and adaptive immunity. Two distinct gammadelta TCL entities are recognized: hepatosplenic T-cell lymphoma (HSTL) and primary cutaneous gammadelta T-cell lymphoma (PCGD-TCL). HSTL is a well-characterized extranodal lymphoma that has a disguised onset, secondary to intrasinusoidal infiltration of the spleen, liver and bone marrow, has a rapidly progressive course that is poorly responsive to chemotherapy, and often ensues in the setting of immune system suppression. PCGD-TCL can present with prominent epidermal involvement or with a panniculitis-like clinical picture that can be complicated by a concurrent hemophagocytic syndrome; the disease shows biological and phenotypic overlap with other extranodal gammadelta TCLs that involve the respiratory or gastrointestinal tract mucosa. The regular application of phenotypic and molecular techniques is crucial for the diagnosis of gammadelta TCLs. In this Review, we discuss the clinical and biological features, the diagnostic challenges and the therapeutic perspectives of HSTL and PCGD-TCL.

Hepatosplenic gammadelta T-cell lymphoma after liver transplantation: report of the first 2 cases and review of the literature

Hepatosplenic gammadelta T-cell lymphoma is a rare lymphoproliferative disorder originating from natural killer-like Vdelta1-lymphocytes. This subtype has been described after different types of solid organ transplants. In this article, we describe the first 2 cases after liver transplantation. Both patients had thrombocytopenia with (hepato)splenomegaly but without peripheral lymphadenopathies and sinusoidal infiltration of the liver and spleen by monomorphic gammadelta-lymphocytes on pathological examination. The clinical and pathological findings, immunophenotypical profile, prognosis, and treatment are highlighted. In order to make an early diagnosis, physicians who take care of liver transplant recipients should be aware of the characteristic features of this posttransplant lymphoproliferative disorder. Therefore, a diagnostic algorithm is proposed.

Hepatosplenic gamma-delta T-cell lymphoma: clinicopathological features and treatment

BACKGROUND

Hepatosplenic T-cell lymphoma (HSTCL) is a rare peripheral T-cell lymphoma; treatment with standard anthracycline-containing chemotherapy regimens has been disappointing, and an optimal treatment strategy for this patient population has not yet been determined.

METHODS

We identified 15 cases of pathologically confirmed HSTCL in the institution's database. Clinical characteristics and treatment results were reviewed.

RESULTS

Complete responses (CRs) were achieved in 7 of 14 patients who received chemotherapy. Achievement of CR was followed by hematopoietic stem-cell transplantation in three patients. Median duration of CR was 8 months (range 2 to 32+ months) with four patients currently alive and in CR at 5, 8, 12, and 32 months, respectively. Median overall survival (OS) was 11 months (range 2 to 36+ months). Patients who achieved a CR had a median OS of 13 months, compared with 7.5 months in patients who did not achieve a CR. Risk factors associated with worse outcome included male gender, failure to achieve a CR, history of immunocompromise, and absence of a T-cell receptor gene rearrangement in the gamma chain.

CONCLUSION

A better understanding of the pathophysiology of HSTCL and new therapeutic strategies are needed.

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.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.