Clonal T-cell Receptor Rearrangements Research Articles

Clinicopathological and molecular genetic alterations in monomorphic–epitheliotropic intestinal T-cell lymphoma of the small intestine

BackgroundSmall intestinal monomorphic–epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare aggressive T-cell lymphoma originating in the gastrointestinal tract. This study aimed to investigate the clinicopathological features, immunophenotypes, and molecular genetic changes of MEITL.MethodsThe clinicopathological data for three patients with surgically resected MEITL of the small intestine were collected. Next, immunohistochemical labeling, Epstein–Barr virus (EBV) in situ hybridization, assessment of clonal rearrangement of T-cell receptor (TCR) genes, and next-generation sequencing (NGS) were performed.ResultsOf the three patients, two were male and one was female, with ages of 61, 67, and 73 years, respectively. Clinical manifestations were predominantly abdominal pain and distension. Histopathology revealed infiltrative growth of small-to-medium-sized lymphocytes with a consistent morphology between the intestinal walls, accompanied by an obvious pro-epithelial phenomenon. The expression of CD3, CD8, CD43, CD56, TIA-1, CD103, H3K36me3, and Bcl-2 was detected, and the Ki-67 proliferation index ranged from 50% to 80%. All three patients tested negative for EBER. However, monoclonal rearrangement of the TCR gene was detected in them. NGS testing showed a JAK3 mutation in all three cases. Further, STAT5B, SETD2, and TP53 mutations were each observed in two cases, and a BCOR mutation was found in one case. All patients were treated with chemotherapy after surgery. Two patients died 7 and 15 month post-operation, and one patient survived for 5 months of follow-up.ConclusionsOur findings demonstrate that mutations in JAK3 and STAT5B of the JAK/STAT pathway and inactivation of the oncogene SETD2 markedly contribute to the lymphomagenesis of MEITL.

Flow Sorting, Whole Genome Amplification and Next-Generation Sequencing as Combined Tools to Study Heterogeneous Acute Lymphoblastic Leukemia.

Next-generation sequencing (NGS) methods have been introduced for immunoglobulin (IG)/T-cell receptor (TR) gene rearrangement analysis in acute lymphoblastic leukemia (ALL) and lymphoma (LBL). These methods likely constitute faster and more sensitive approaches to analyze heterogenous cases of ALL/LBL, yet it is not known whether gene rearrangements constituting low percentages of the total sequence reads represent minor subpopulations of malignant cells or background IG/TR gene rearrangements in normal B-and T-cells. In a comparison of eight cases of B-cell precursor ALL (BCP-ALL) using both the EuroClonality NGS method and the IdentiClone multiplex-PCR/gene-scanning method, the NGS method identified between 29% and 139% more markers than the gene-scanning method, depending on whether the NGS data analysis used a threshold of 5% or 1%, respectively. As an alternative to using low thresholds, we show that IG/TR gene rearrangements in subpopulations of cancer cells can be discriminated from background IG/TR gene rearrangements in normal B-and T-cells through a combination of flow cytometry cell sorting and multiple displacement amplification (MDA)-based whole genome amplification (WGA) prior to the NGS. Using this approach to investigate the clonal evolution in a BCP-ALL patient with double relapse, clonal TR rearrangements were found in sorted leukemic cells at the time of second relapse that could be identified at the time of diagnosis, below 1% of the total sequence reads. These data emphasize that caution should be exerted when interpreting rare sequences in NGS experiments and show the advantage of employing the flow sorting of malignant cell populations in NGS clonality assessments.

Serological and Molecular Characterization of Hepatitis C Virus-Related Cryoglobulinemic Vasculitis in Patients without Cryoprecipitate.

Prolonged B cells stimulation due to the Hepatitis C virus (HCV) can result in autoimmunity, stigmatized by rising levels of cryoglobulins (CGs), the rheumatoid factor (RF), and free light chains (FLC) of immunoglobulins (Ig) associated with a range of symptoms, from their absence to severe cryoglobulinemic vasculitis and lymphoma. Here, we aimed to identify an immunological signature for the earliest stages of vasculitis when cryoprecipitate is still not detectable. We firstly analyzed the IgG subclasses, FLC, and RF in 120 HCV-RNA-positive patients divided into four groups according to the type of cryoprecipitate and symptoms: 30 asymptomatic without cryoprecipitate (No Cryo), 30 with vasculitis symptoms but without CGs that we supposed were circulating but still not detectable (Circulating), 30 type II and 30 type III mixed cryoglobulinemia (Cryo II and Cryo III, respectively). Our results revealed that patients with supposed circulating CGs displayed a pattern of serological parameters that closely resembled Cryo II and Cryo III, with a stronger similarity to Cryo II. Accordingly, we analyzed the groups of Circulating and Cryo II for their immunoglobulin heavy chain (IgH) and T-cell receptor (TCR) gene rearrangements, finding a similar mixed distribution of monoclonal, oligoclonal, and polyclonal responses compared to a control group of ten HCV-RNA-negative patients recovered from infection, who displayed a 100% polyclonal response. Our results strengthened the hypothesis that circulating CGs are the origin of symptoms in HCV-RNA-positive patients without cryoprecipitate and demonstrated that an analysis of clonal IGH and TCR rearrangements is the best option for the early diagnosis of extrahepatic complications.

Prevalence of STAT3 mutations in patients with rheumatoid arthritis-associated T-cell large granular lymphocytic leukaemia and Felty syndrome.

Neutropenia is a key presentation of Felty syndrome (FS) and rheumatoid arthritis (RA)-associated T-cell large granular lymphocytic (T-LGL) leukaemia. Clonal rearrangement of T-cell receptor (TCR) gene supports the diagnosis of T-LGL leukaemia but not FS. Mutations in the signal transducer and activator of transcription 3 (STAT3) gene are highly specific for T-LGL leukaemia, but their prevalence in FS remains poorly clarified. The study included 100 patients with RA and unexplained neutropenia. TCR rearrangements were examined in blood (100 cases), bone marrow (47 cases), and spleen (12 cases) using the BIOMED-2 protocol. Patients were stratified into RA-associated T-LGL leukaemia cohort if a clonal TCR rearrangement was identified in any of the tested patient samples, and into FS cohort in other cases. Mutations in the STAT3 were examined using next-generation sequencing (NGS) technology in blood (100 cases), bone marrow (37 cases), and spleen (7 cases). STAT3 mutations were identified in 71% (49/69) patients with RA-associated T-LGL leukaemia and in 10% (3/31) patients with FS (p=4.7×10-8). Three samples from the RA-associated T-LGL leukaemia cohort and 5 samples from the FS cohort had STAT3 mutations in the absence of clonal TCR rearrangement. The results suggest that STAT3 mutations are significantly less common in FS than in RA-associated T-LGL leukaemia. Moreover, NGS can detect clones undetectable by fragment analysis. We speculate that in patients with RA and neutropenia, the detection of STAT3 mutations can point to T-LGL leukaemia even in the absence of clonal TCR rearrangement.

STAT3 mutations in "gray-zone" cases of T-cell large granular lymphocytic leukemia associated with autoimmune rheumatic diseases.

A persistently increased T-cell large granular lymphocyte (T-LGL) count in the blood of more than 2 × 109/L for at least 6 months is necessary for a reliable diagnosis of T-LGL leukemia. In cases with LGL counts of approximately 0.5–2 × 109/L, a diagnosis of T-LGL leukemia can be made if clonal rearrangement of T-cell receptor (TCR) genes is present and if the patient shows typical manifestations of T-LGL leukemia, such as cytopenia, splenomegaly, or concomitant autoimmune disease. However, in cases with LGL counts of less than 0.5 × 109/L, the diagnosis of T-LGL leukemia is questionable (termed as “gray-zone” cases). Although mutations in signal transducer and activator of transcription 3 (STAT3) gene are the molecular hallmark of T-LGL leukemia, their diagnostic value in the “gray-zone” cases of T-LGL leukemia has not been evaluated – our study has been aimed to examine the prevalence of STAT3 mutations in these cases. Herein, we describe 25 patients with autoimmune rheumatic diseases, neutropenia, clonal rearrangement of TCR genes, and circulating LGL count of less than 0.5 × 109/L. Splenomegaly was observed in 19 (76%) patients. Mutations in the STAT3 were detected in 56% of patients using next-generation sequencing. Importantly, in 3 patients, no involvement of the blood and bone marrow by malignant LGLs was noted, but examination of splenic tissue revealed infiltration by clonal cytotoxic T-lymphocytes within the red pulp, with greater prominence in the cords. We suggest using the term “splenic variant of T-LGL leukemia” for such cases.

T-cell-derived Hodgkin lymphoma has motility characteristics intermediate between Hodgkin and anaplastic large cell lymphoma.

Classic Hodgkin lymphoma (cHL) is usually characterized by a low tumour cell content, derived from crippled germinal centre B cells. Rare cases have been described in which the tumour cells show clonal T‐cell receptor rearrangements. From a clinicopathological perspective, it is unclear if these cases should be classified as cHL or anaplastic large T‐cell lymphoma (ALCL). Since we recently observed differences in the motility of ALCL and cHL tumour cells, here, we aimed to obtain a better understanding of T‐cell‐derived cHL by investigating their global proteomic profiles and their motility. In a proteomics analysis, when only motility‐associated proteins were regarded, T‐cell‐derived cHL cell lines showed the highest similarity to ALK− ALCL cell lines. In contrast, T‐cell‐derived cHL cell lines presented a very low overall motility, similar to that observed in conventional cHL. Whereas all ALCL cell lines, as well as T‐cell‐derived cHL, predominantly presented an amoeboid migration pattern with uropod at the rear, conventional cHL never presented with uropods. The migration of ALCL cell lines was strongly impaired upon application of different inhibitors. This effect was less pronounced in cHL cell lines and almost invisible in T‐cell‐derived cHL. In summary, our cell line‐derived data suggest that based on proteomics and migration behaviour, T‐cell‐derived cHL is a neoplasm that shares features with both cHL and ALCL and is not an ALCL with low tumour cell content. Complementary clinical studies on this lymphoma are warranted.

Tre-P-24 - Aggressive gamma/delta T-cell lymphoma: successful therapy with encapsulated doxorubicin

An 82-year-old female patient initially presented with a prominent, reddish-livid, sharply circumscribed tumor measuring 10×5.5 cm on the left forearm, as well as multiple small-nodular efflorescences on both arms, the trunk, and the dorsum of the feet. The histologic picture was consistent with peripheral T-cell lymphoma. Immunohistochemical workup showed CD3 expression, high proliferative activity at 70%, and staining with gamma and delta showed the impressive picture of a consistently homogeneous reaction product with delta. No clonal T-cell receptor rearrangement was found in the molecular workup. Initial staging showed no systemic involvement (pT3N0M0). We initially treated with twelve doses of gemcitabine 600 mg fix-dose and local radiotherapy of the tumor node on the left forearm. As the cutaneous manifestations progressed, we switched to off-label therapy with pembrolizumab 200 mg every three weeks in combination with radiotherapy of the tumor nodes on the right forearm, legs and feet on both sides. As the cutaneous tumors progressed again after seven doses of pembrolizumab, therapy was switched to liposomal encapsulated doxorubicin, initially 20 mg/m2 on days 1 and 15, then every four weeks. With this therapy, tumor response has been good after six administrations to date, allowing the dose to be KOF to 10 mg/m2. Incidentally, the patient suffered from arterial hypertension and sigmoid diverticulosis. Primary cutaneous gamma/delta T-cell lymphomas are a heterogeneous group of rare and highly aggressive lymphomas. Median survival is 31 months, as they are largely resistant to radiotherapy and chemotherapy. Allogeneic stem cell transplantation offers the only curative therapy. There is no standard therapy due to the low incidence and lack of prospective studies, so that an individual therapy decision must be made for each patient. Encapsulated doxorubicin may be a good therapeutic alternative to control this highly aggressive lymphoma. As an addititional immunohistochemical workup also showed a homogenous BcL2 expression in our case, the BcL2-inhbitor Venetoclax could offer a future therapeutic option.

The Value of Flow Cytometry Clonality in Large Granular Lymphocyte Leukemia.

Simple SummaryLarge granular lymphocyte (LGL) leukemia, a lymphoproliferative disease, is characterized by an increased frequency of large-sized lymphocytes with typical expression of T-cell receptor (TCR) αβ, CD3, CD8, CD16, CD45RA, and CD57, and with the expansion of one to three subfamilies of the TCR variable β chain reflecting gene rearrangements. Molecular analysis remains the gold standard for confirmation of TCR clonality; however, flow cytometry is time and labor saving, and can be associated with simultaneous investigation of other surface markers. Moreover, Vβ usage by flow cytometry can be employed for monitoring clonal kinetics during treatment and follow-up of LGL leukemia patients.Large granular lymphocyte (LGL) leukemia is a lymphoproliferative disorder of mature T or NK cells frequently associated with autoimmune disorders and other hematological conditions, such as myelodysplastic syndromes. Immunophenotype of LGL cells is similar to that of effector memory CD8+ T cells with T-cell receptor (TCR) clonality defined by molecular and/or flow cytometric analysis. Vβ usage by flow cytometry can identify clonal TCR rearrangements at the protein level, and is fast, sensitive, and almost always available in every Hematology Center. Moreover, Vβ usage can be associated with immunophenotypic characterization of LGL clone in a multiparametric staining, and clonal kinetics can be easily monitored during treatment and follow-up. Finally, Vβ usage by flow cytometry might identify LGL clones silently underlying other hematological conditions, and routine characterization of Vβ skewing might identify recurrent TCR rearrangements that might trigger aberrant immune responses during hematological or autoimmune conditions.

Clonal T-cell large granular lymphocyte proliferations in childhood and young adult immune dysregulation conditions.

Proliferation of large granular lymphocytes (LGL) and T-cell LGL (T-LGL) in peripheral blood along with demonstration of clonality are the hallmarks of a heterogeneous group of disorders, including T-LGL leukemia or T-LGL lymphocytosis. They are often associated with neutropenia and responsive to immunosuppression. The true nature of this entity is not well understood. Some cases are reported as reactive phenomena with very limited experience in pediatric population. Hematology/Oncology Flow Cytometry Laboratory database has been reviewed retrospectively. Patients with identifiable distinct CD5-dim T-cell population and positive clonal T-cell receptor rearrangement were included in the analysis. Clinical and laboratory data were then reviewed. Sixteen cases of children and young adults with increased peripheral blood clonal T-LGL population characterized by dim CD5 expression with wide range of underlying immune dysregulation/stimulation disorders were reviewed. Extended follow up with repeat testing suggested the reactive nature of persistent clonal T-LGL proliferations in this group. Our observations indicate that clonal T-LGL proliferations in children and young adults are reactive in nature and some can be persistent with an indolent course with unknown consequentiality. Clonal T-LGL cells could be targeting the most prominent immunogenic stressor(s) involved as a control mechanism.

Blockade of IL-15 Utilizing Bnz-1, a Selective γ-Chain Inhibiting Peptide, Is Safe and Has Clinical Activity in Patients with T-Cell Large Granular Lymphocytic Leukemia (T-LGLL): Results of a Phase I/II Multi-Center Clinical Trial

T-cell large granular lymphocytic leukemia (T-LGLL) is an incurable, and likely under-diagnosed leukemia characterized by abnormal clonal proliferation of CD8+ memory T-cells. The clonal outgrowth of T-LGLL cells can lead to the development of profound neutropenia and anemia which results in frequent infections, transfusion dependence, and impairment in quality of life and lifespan. There have been few prospective clinical trials in this disease, and no drugs have been FDA approved for its treatment. The primary driver of leukemogenesis in T-LGLL is known to be interleukin-15 (IL-15), a gamma-chain cytokine that induces proliferation of T-LGLL cells. BNZ-1 is a novel pegylated peptide antagonist that inhibits IL-15 by binding to the common γ-chain receptor for cytokines IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. Studies utilizing BNZ-1 in vitro on T-LGLL cell lines, and ex vivo on clinical patient samples demonstrated significant inhibition of downstream signaling and increased LGLL cell apoptosis (Wang et al., Leukemia 2018). Given these results, we conducted a phase I/II dose escalation study to evaluate the safety, maximum tolerated dose (MTD), and preliminary efficacy of BNZ-1 in T-LGLL (NCT03239393). Patients with T-LGLL were eligible if they had one or more of the following: absolute neutrophil count (ANC) <500 cells/m3, neutropenia with recurrent infections, or symptomatic or transfusion-dependent anemia. Diagnosis of T-LGLL required: >400/mm3 CD3+CD57+ cells or >650 mm3 CD8+ cells, with a clonal T-cell receptor rearrangement. No prior therapy within 30 days or 5 half-lives was permitted. MTD was evaluated using a standard 3+3 design; with a dose escalation strategy using four doses of BNZ-1: 0.5 mg/kg, 1 mg/kg, 2 mg/kg, and 4 mg/kg. BNZ-1 was administered by infusion on Days 1, 8, 15, and 22 of a 4-week cycle. Patients then had the option to enter the 3-month extension period, at the same weekly dose. Efficacy was determined utilizing criteria from the ECOG5998 study in T-LGLL. CR was defined as complete normalization of blood counts. Partial response (PR) in neutropenic patients was determined by 4 weeks or greater response with ANC >500 cells/mm3 if >/=50% improvement from baseline. For transfusion-dependent anemia patients, a >/=50% decrease in monthly transfusions for at least 2 months was required for a PR. For patients with symptomatic anemia, improvement in hemoglobin >/=1 g/dL with improvement in symptoms constituted a PR. Patients with a response were permitted to remain on a long-term extension (LTE). Eighteen patients, at 3 US centers were enrolled on study including: 3 patients at 0.5 mg/kg, 4 at 1 mg/kg, 5 at 2 mg/kg, and 6 at 4 mg/kg. 10 patients were enrolled for neutropenia, 4 for transfusion dependent anemia, 2 for symptomatic anemia, and 2 with anemia and neutropenia. 15 patients (83%) completed all 16 weeks of treatment, 2 patients declined to enter the extension phase, and one patient on the 2 mg/kg dosage was taken off study at 4 weeks due to neutropenia <100 thought secondary to T-LGLL. One patient developed grade 2 hyperbilirubinemia, which was thought possibly due to study drug though was grade 1 at baseline.The MTD was not reached. Four patients attained a PR: 3 patients with transfusion-dependent anemia became transfusion independent, while one patient with neutropenia had significant resolution of her neutropenia (Table). These three patients remain on the LTE, though one patient is under observation. Correlative studies demonstrated apoptosis of T-LGLL cells on flow cytometry utilizing CD3 T-cell gating within 24 hours of the first dosage of BNZ-1 (a representative example is shown in the Figure), confirming in patients that inhibition of IL-15 induces apoptosis of T-LGLL cells. In this Phase I/II clinical trial, IL-15 blockade utilizing BNZ-1 demonstrated increased apoptosis in patients with T-LGLL, with early evidence of clinical response, particularly amongst patients with transfusion-dependent anemia. Remarkably, these patients remained transfusion-independent while on BNZ-1. The MTD was not reached in this cohort of patients, and there were minimal AEs associated with BNZ-1. Further analysis of responding patients is underway to determine the most effective approach utilizing BNZ-1 in this rare disease. Table Disclosures Brammer: Celgene: Research Funding; Seatlle Genetics: Honoraria, Speakers Bureau. Sokol:EUSA: Consultancy. Tagaya:Bioniz: Membership on an entity's Board of Directors or advisory committees; Bioniz: Research Funding. Rogers:AbbVie: Research Funding; Acerta Pharma: Consultancy; Genentech: Research Funding; Janssen: Research Funding. Waldmann:Bioniz: Membership on an entity's Board of Directors or advisory committees. Azimi:Bioniz: Employment. Frohna:Bioniz: Employment. Ratnayake:Bioniz: Employment. Loughran:Bioniz: Membership on an entity's Board of Directors or advisory committees; Keystone Nano: Membership on an entity's Board of Directors or advisory committees.

T-Cell Clonal Expansion and Activation Associated with Durable Clinical Response to Dual BTK and CDK4/6 Inhibitor Therapy in Mantle Cell Lymphoma

T-Cell Clonal Expansion and Activation Associated with Durable Clinical Response to Dual BTK and CDK4/6 Inhibitor Therapy in Mantle Cell Lymphoma

Decitabine-containing G-CSF priming regimen overcomes resistance of primary mediastinal neoplasm from early T-cell precursors to conventional chemotherapy: a case report.

Early T-cell precursor (ETP) leukemia represents a new subtype of T-lymphoblastic leukemia/lymphoma with unique immunophenotypes expressing T-cell and one or more of the myeloid/stem cell markers. Here, we report a young patient who had primary mediastinal mass and pleural effusion without bone marrow involvement. A CT-guided mediastinal biopsy and flow cytometry analysis of the pleural effusion revealed the blast cells to have complicated immunophenotypes: strongly expressed T-cell antigen CD7, myeloid-lineage antigens CD33 and CD13 and stem cell markers cTdT, CD34, and HLA-DR; dimly expressed myeloid-lineage specific antigen cMPO and B-cell antigen cCD79a; but did not express T-cell specific antigen cytoplasmic CD3 and B-cell specific antigen CD19. Clonal T-cell receptor rearrangement eventually determined the cell of origin from ETPs, not myeloblasts. The patient showed primary resistance to lymphoid and myeloid-directed induction therapy. Finally, low-dose decitabine combined with modified-CAG regimen induced a complete remission and allogeneic stem cell transplantation was performed as consolidation. The case indicates a primary mediastinal neoplasm from ETP with distinctive immunophenotype from leukemia type. Low-dose decitabine and modified-CAG regimen in combination with allogeneic stem cell transplantation may improve the outcome of patient.

Clonal T-Large Granular Lymphocyte Proliferations in Childhood: Friend or Foe?

Background: The pathophysiology of clonal T-large granular lymphocyte (T-LGL) proliferations is not well understood; the distinction between reactive and malignant entities is not very clear given the fact that acquired STAT3 mutations can be seen with clonal T-LGL proliferations in non-malignant Felty syndrome and with frequent use of immunosuppression for the treatment of T-LGL leukemia. Historically, determination of clonality has been often seen as an indicator of T-LGL leukemia. We reviewed our experience on clonal T-LGL proliferations in children.Material and Methods: T-LGLs were identified by CD3 and dim CD5 staining on flow cytometric analysis and observation of lymphocytes with large granular cytoplasm appearance in peripheral blood. Cases with peripheral blood lymphocyte T-LGL population greater than 10% were reviewed in patients whom had flow cytometry studies performed for different indications. Among them, ones with available T cell receptor (TCR) gene rearrangement studies were selected and 16 cases with clonal TCR rearrangement patterns were included in this study. Fifty-seven peripheral blood flow cytometric tests using 15 surface markers were analyzed in those 16 cases. Patients have been followed for up to 7 years.Results: Sixteen cases of clonal T-LGL proliferation associated with different diseases were included in this analysis. Three patients had chronic graft versus host disease, 2 Evans syndrome, and one case each with the following conditions: common variable immunodeficiency disorder, severe combined immunodeficiency who developed CMV infection following umbilical cord blood transplantation (UCBT) and later acute EBV infection, co-existing Langerhans cell histiocytosis and primary hemophagocytic lymphohistiocytosis, autoimmune hemolytic anemia, chronic idiopathic thrombocytopenic thrombocytopenia, Hodgkin lymphoma, X-linked lymphoproliferative disorder, Rosai Dorfman disease (RDD), acute EBV infection, acute parvovirus B19 infection and paroxysmal nocturnal hemoglobinuria with history of treated severe aplastic anemia. Pathophysiological processes involved in these cases included various combinations of inherited immune deficiency in 4, acquired immune deficiency in 5, lymphoproliferation in 6, alloimmune reaction in 3, autoimmune reaction in 5, infection in 4, inflammation in 3 and malignancy in 1. One patient had three different clonal populations at different times due to maternal engraftment, CMV infection following UCBT and during an acute EBV infection after immune suppression withdrawal, respectively. The patient with RDD developed clonal T-LGL expansion when his disease flared. In some cases, clonal T-LGL proliferations disappeared with the resolution of the underlying pathological process. However, the T-LGL clone persisted and was frequently associated with relative increase over time, if the disease process continued to be active and/or progressed, even despite use of therapeutic approaches often including immunosuppression. Four clonal T-LGL proliferations in 2 patients have resolved, remaining 10 were persistent and have not been reevaluated in 4 cases. None of the cases showed a purely monoclonal pattern. The size of the clonal T-LGL population was variable with a median value of 18.6%, as high as 58.7% of the lymphocyte population. T-LGL population has positively correlated with CD3, CD8, CD57 (p<0.001) and inversely with CD19 (p=0.001) expression. There was also an overall positive correlation between the percent of T-LGL cells and absolute T-LGL count (p<0.001).Discussion: Clonal T-LGL proliferations in childhood is a reactive process reflecting the activity of the underlying disease process, including immunodeficiency, autoimmunity, alloimmunity, infection, inflammation, lymphoproliferation and malignancy. Use of immunosuppression has been associated with relative increase in the clone size despite decrease in peripheral blood absolute lymphocyte count along with relative reduction in T and B lymphocyte compartments in patients with active disease. Presence of clonal T-LGL proliferations in a polyclonal background is not an indicator of malignant process. It is very possible that such proliferations are an effort of the immune system to control the most prominently involved immunogenic stressors. DisclosuresNo relevant conflicts of interest to declare.

Clinicopathologic features of adult EBV-associated B-cell lymphoproliferative disease

In the present study, 21 cases of adult/late-onset EBV-associated lymphoproliferative disease (AELPD) with an uncertain malignant potential were investigated with regard to their histomorphology, immunophenotype, clonal rearrangement of the heavy chain (IgH) and T-cell receptor (TCR) genes and clinical course.The cases were histomorphologically reevaluated and assigned to one of three morphological groups: mononucleosis-like, Hodgkin-like, or polymorphous. In addition, cases with or without detectable necrosis were investigated for differences in clinical outcome.Overall survival was highest in the group with Hodgkin-like morphology (4/4 patients), followed by patients with mononucleosis-like phenotype (4/5 patients surviving). Cases with polymorphous morphology showed the poorest survival rates with 7/12 patients dead of disease (58%). 4/6 patients with histologically detectable necrosis died (66%), but only 4/15 patients without necrosis (27%). 11/21 cases with AELPD showed clonal rearrangement for IgH (n = 4), TCR (n = 5) or IgH + TCR (n = 2). 5/11 patients with clonal rearrangement died (45%), and this percentage was similar in all of the three subgroups.In conclusion, the present study shows that polymorphous morphology and detection of necrosis in AELPD are frequently linked to a fatal clinical course, whereas Hodgkin-like morphology seems to be associated with a more favourable prognosis. Clonal rearrangement of IgH or TCR is frequent in AELPD, but prognosis is unpredictable from this feature.

Idiopathic hypereosinophilia is clonal disorder? Clonality identified by targeted sequencing.

Idiopathic hypereosinophilia (IHE)/idiopathic hypereosinophilic syndrome (IHES) has been defined by a persistent elevation of the blood eosinophil count exceeding 1.5×103/μL, without evidence of reactive or clonal causes. While T-cell clonality assessment has been recommended for unexplained hypereosinophilia, this approach is not often applied to routine practice in the clinic. We hypothesized that the clonality would exist in a subset of IHE/IHES patients. We aimed to investigate the candidate mutations and T-cell clonality in IHE/IHES and to explore the role of mutations in eosinophil proliferation. We performed targeted capture sequencing for 88 genes using next-generation sequencing, T-cell receptor (TCR) gene rearrangement assays, and pathway network analysis in relation to eosinophil proliferation. By targeted sequencing, 140 variants in 59 genes were identified. Sixteen out of 30 patients (53.3%) harbored at least one candidate mutation. The most frequently affected genes were NOTCH1 (26.7%), SCRIB and STAG2 (16.7%), and SH2B3 (13.3%). Network analysis revealed that our 21 candidate genes (BIRC3, BRD4, CSF3R, DNMT3A, EGR2, EZH2, FAT4, FLT3, GATA2, IKZF, JAK2, MAPK1, MPL, NF1, NOTCH1, PTEN, RB1, RUNX1, TET2, TP53 and WT1) are functionally linked to the eosinophilopoietic pathway. Among the 21 candidate genes, five genes (MAPK1, RUNX1, GATA2, NOTCH1 and TP53) with the highest number of linkages were considered major genes. A TCR assay revealed that four patients (13.3%) had a clonal TCR rearrangement. NOTCH1 was the most frequently mutated gene and was shown to be a common node for eosinophilopoiesis in our network analysis, while the possibility of hidden T cell malignancy was indwelling in the presence of NOTCH1 mutation, though not revealed by aberrant T cell study. Collectively, these results provide new evidence that mutations affecting eosinophilopoiesis underlie a subset of IHE/IHES, and the candidate genes are inferred to act their potential roles in the eosinophilopoietic pathway.

Staring inside of Idiopathic Hypereosinophilia: Identification of Clonality Using Targeted Exome Sequencing

Idiopathic hypereosinophilia (IHE) has been a disorder of uncertain etiology, characterized by persistent elevation of blood eosinophil count exceeding 1.5x103/μL without evidence of reactive and clonal causes. When end-organ damage due to eosinophilic infiltration is present, idiopathic hypereosinophilic syndrome (IHES) is diagnosed. As the name 'idiopathic' implies the uncertain etiology, the nature of eosinophilic proliferation is unclear whether benign or clonal. While T cell clonality assessment has been recommended for unexplained hypereosinophilia, this approach is not often applied to the routine practice in clinic. We hypothesized that the clonality would exist in patients classified into IHE/IHES. The bone marrow cells of 30 IHE patients were retrospectively evaluated.The T cell receptor (TCR) assay and the targeted sequencing for 88 genes related to hematologic malignancies were performed. After being analyzed, the candidate mutations were subjected to pathway analysis.Through the targeted sequencing, 140 variants in 59 genes were identified. Sixteen out of 30 patients (53.3%) harbored at least 1 candidate mutation. The most frequently affected genes were NOTCH (n=8); SCRIB and STAG2 (n=5); SH2B3 (n=4). Remarkably, we identified recurrent somatic mutations in 4 genes with 5 patients (16.7%); MPLY521X (n=2), SCRIBE795X (n=2), ASXL1G646f (n=3) and STAG2E249X (n=2). A known mutation TP53V216M was confirmed in an IHE patient. Interestingly, the TCR assay revealed that 4 of 30 patients (13.3%) had a clonal TCR rearrangement. Skin involvement was described in patients with clonal T cell population. Through the pathway analysis, the role of these genes in eosinophilia was identified. These results highly suggest that these genes are likely related to clonality of hypereosinophilia.This study revealed that somatic mutations affecting hematopoiesis and monoclonal T cell clones underlie idiopathic hypereosinophilia. It would be valuable to extend our findings on the molecular profiling of hypereosinophilia to the further study discovering the clonality of IHE. DisclosuresNo relevant conflicts of interest to declare.

Intralymphatic Proliferation of T-cell Lymphoid Blasts in the Setting of Hidradenitis Suppurativa

Intralymphatic proliferation of T-cell lymphoid blasts (IPTCLBs) is a rare, recently described entity, associated with cutaneous inflammatory conditions and characterized by intralymphatic proliferation of highly proliferating, blastoid T lymphocytes expressing CD30, thus mimicking an intravascular lymphoma. In all reported cases, the intralymphatic proliferation was associated with an underlying inflammatory condition, with no clonal T-cell receptor rearrangement, no signs of systemic or cutaneous lymphoma, and excellent prognosis. The authors present a new case of IPTCLB arising in a patient with hidradenitis suppurativa. Histological examination revealed a dilated follicle embedded within a fibrotic stroma surrounded by a dense lymphoid infiltrate characterized by the presence of dilated small vessels filled with atypical medium-to-large sized blastoid lymphocytes expressing a CD4 T phenotype. There was also expression of CD30, but negativity for cytotoxic markers and Epstein-Barr virus. The proliferation index was high and the vessels showed expression of D2-40, confirming their lymphatic nature. No signs of systemic lymphoma could be detected after routine investigations, and the patient is alive and in good general health. IPTCLB is a rare benign entity that presents with worrying, potentially misleading histopathological features that mimic those observed in intravascular lymphoma. Careful histological and phenotypic investigations and correlation with the clinical features are necessary for a proper diagnosis.

Anaplastic large cell lymphoma arises in thymocytes and requires transient TCR expression for thymic egress.

Anaplastic large cell lymphoma (ALCL) is a peripheral T-cell lymphoma presenting mostly in children and young adults. The natural progression of this disease is largely unknown as is the identity of its true cell of origin. Here we present a model of peripheral ALCL pathogenesis where the malignancy is initiated in early thymocytes, before T-cell receptor (TCR) β-rearrangement, which is bypassed in CD4/NPM–ALK transgenic mice following Notch1 expression. However, we find that a TCR is required for thymic egress and development of peripheral murine tumours, yet this TCR must be downregulated for T-cell lymphomagenesis. In keeping with this, clonal TCR rearrangements in human ALCL are predominantly in-frame, but often aberrant, with clonal TCRα but no comparable clonal TCRβ rearrangement, yielding events that would not normally be permissive for survival during thymic development. Children affected by ALCL may thus harbour thymic lymphoma-initiating cells capable of seeding relapse after chemotherapy.

Immunophenotypic shift of CD4 and CD8 antigen expression in primary cutaneous T‐cell lymphomas: a clinicopathologic study of three cases

Primary cutaneous T-cell lymphomas (CTCL) comprise a heterogeneous group of neoplasms with diverse clinical behavior. Mycosis fungoides (MF) is the most common type of CTCL. Immunophenotypical shift during progression of the disease is a rare event and its significance is unknown. We present three primary CTCL cases that showed an immunophenotypical shift and poor prognosis. Conventional hematoxylin/eosin and immunohistochemical-stained sections were examined in all the cases. Molecular analysis for rearrangement of the T-cell receptor (TCR) gene was performed in two cases. One case was classified as MF, while the other two lacked epidermotropism, and were considered primary cutaneous peripheral T-cell lymphoma (PTCL), NOS. Two cases were CD3+/CD4+ and one case was CD3+/CD8+ at diagnosis. The first two patients suffered many relapses and eventually, new CTCL lesions with a CD3+/CD8+ phenotype were observed. Both cases revealed identical clonal TCR rearrangements on the initial and late lesions, supporting the interpretation of a single clonal proliferation with different phenotypes. The third case progressed with skin recurrences and pulmonary lesions with a predominant CD3+/CD4+/CD8- phenotype. All cases manifested poor prognosis and two patients died of lymphoma. Immunophenotypical shift between CD4 and CD8 in CTCL seems to be a rare phenomenon that may be associated with disease progression.

Apoptotic cells and clonally expanded cytotoxic T cells in bone marrow trephines of patients with myelodysplastic syndrome

There is increasing evidence that autoimmunity is involved in the pathogenesis of myelodysplastic syndromes (MDS). We examined the number of apoptotic cells, and analysed the T cells and the T cell receptor gene rearrangements in bone marrow trephines of patients with low-grade MDS [refractory anaemia (RA), refractory anaemia with ringed sideroblasts (RAS) and refractory cytopenia with multilineage dysplasia (RCMD)] to investigate the correlation between T cells and apoptosis. Bone marrow trephines from 30 patients with RA, seven patients with RCMD, four patients with RAS and 11 normal bone marrow donors were stained for CD3 and for apoptotic cells using immunohistochemistry and terminal deoxynucleotidyl transferase 2'-deoxyuridine, 5'-triphosphate (dUTP) nick end labelling (TUNEL) technique, respectively. The positive cells were quantified by computer-assisted image analysis. In addition, CD 8 and T cell-restricted intracellular antigen-1 (TIA-1)-positive cells were analysed by single staining and evaluated semiquantitatively by light microscopy. Junctional diversity of the T cell receptor (TCR) α-, β- and γ-chains were analysed in 24 cases of RA and RCMD by reverse transcription-polymerase chain reaction (RT-PCR). In all cases of RA, RCMD and RAS an increase of apoptotic cells was accompanied by an increase of T cells, when compared to normal donors (P < 0.001). Expression of TIA-1 was found in 33 of 41 patients with low-grade MDS. In contrast, normal controls showed either no or only very weak expression. Furthermore, 14 of 24 cases with low-grade MDS showed clonal TCR gene rearrangement. These findings provide evidence that increased apoptosis in low-grade MDS correlates with increased numbers of cytotoxic T cells. A considerable proportion of the MDS cases showed clonal TCR rearrangement suggesting an antigen-driven selection of the T cells. We therefore speculate that cases of MDS can be accompanied by a presumably autoreactive T cell-mediated apoptosis induction in bone marrow cells.