Refining the diagnosis of T-cell large granular lymphocytic leukemia by combining distinct patterns of antigen expression with T-cell clonality studies

T-Cell Prolymphocytic Leukemia: Diagnosis, Pathogenesis, and Treatment

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells. Most patients with T-PLL present with lymphocytosis, anemia, thrombocytopenia, and hepatosplenomegaly. Correct identification of T-PLL is essential because treatment for this disease is distinct from that of other T-cell neoplasms. In 2019, the T-PLL International Study Group (TPLL-ISG) established criteria for the diagnosis, staging, and assessment of response to treatment of T-PLL with the goal of harmonizing research efforts and supporting clinical decision-making. T-PLL pathogenesis is commonly driven by T-cell leukemia 1 (TCL1) overexpression and ATM loss, genetic alterations that are incorporated into the TPLL-ISG diagnostic criteria. The cooperativity between TCL1 family members and ATM is seemingly unique to T-PLL across the spectrum of T-cell neoplasms. The role of the T-cell receptor, its downstream kinases, and JAK/STAT signaling are also emerging themes in disease pathogenesis and have obvious therapeutic implications. Despite improved understanding of disease pathogenesis, alemtuzumab remains the frontline therapy in the treatment of naïve patients with indications for treatment given its high response rate. Unfortunately, the responses achieved are rarely durable, and the majority of patients are not candidates for consolidation with hematopoietic stem cell transplantation. Improved understanding of T-PLL pathogenesis has unveiled novel therapeutic vulnerabilities that may change the natural history of this lymphoproliferative neoplasm and will be the focus of this concise review.

Uncovering the significance of expanded CD8+ large granular lymphocytes in inclusion body myositis: Insights into T cell phenotype and functional alterations, and disease severity

Introduction

Inclusion body myositis (IBM) is a progressive inflammatory myopathy characterised by skeletal muscle infiltration and myofibre invasion by CD8+ T lymphocytes. In some cases, IBM has been reported to be associated with a systemic lymphoproliferative disorder of CD8+ T cells exhibiting a highly differentiated effector phenotype known as T cell Large Granular Lymphocytic Leukemia (T-LGLL).

Methods

We investigated the incidence of a CD8+ T-LGL lymphoproliferative disorder in 85 IBM patients and an aged-matched group of 56 Healthy Controls (HC). Further, we analysed the phenotypical characteristics of the expanded T-LGLs and investigated whether their occurrence was associated with any particular HLA alleles or clinical characteristics.

Results

Blood cell analysis by flow cytometry revealed expansion of T-LGLs in 34 of the 85 (40%) IBM patients. The T cell immunophenotype of T-LGLHIGH patients was characterised by increased expression of surface molecules including CD57 and KLRG1, and to a lesser extent of CD94 and CD56 predominantly in CD8+ T cells, although we also observed modest changes in CD4+ T cells and γδ T cells. Analysis of Ki67 in CD57+ KLRG1+ T cells revealed that only a small proportion of these cells was proliferating. Comparative analysis of CD8+ and CD4+ T cells isolated from matched blood and muscle samples donated by three patients indicated a consistent pattern of more pronounced alterations in muscles, although not significant due to small sample size. In the T-LGLHIGH patient group, we found increased frequencies of perforin-producing CD8+ and CD4+ T cells that were moderately correlated to combined CD57 and KLRG1 expression. Investigation of the HLA haplotypes of 75 IBM patients identified that carriage of the HLA-C*14:02:01 allele was significantly higher in T-LGLHIGH compared to T-LGLLOW individuals. Expansion of T-LGL was not significantly associated with seropositivity patient status for anti-cytosolic 5'-nucleotidase 1A autoantibodies. Clinically, the age at disease onset and disease duration were similar in the T-LGLHIGH and T-LGLLOW patient groups. However, metadata analysis of functional alterations indicated that patients with expanded T-LGL more frequently relied on mobility aids than T-LGLLOW patients indicating greater disease severity.

Conclusion

Altogether, these results suggest that T-LGL expansion occurring in IBM patients is correlated with exacerbated immune dysregulation and increased disease burden.

Inclusion body myositis: Update on the diagnostic and therapeutic landscape

Inclusion body myositis (IBM) is a progressive muscle disease affecting patients over the age of 40, with distinctive clinical and histopathological features. The typical clinical phenotype is characterized by prominent involvement of deep finger flexors and quadriceps muscles. Less common presentations include isolated dysphagia, asymptomatic hyper-CKemia, and axial or limb weakness beyond the typical pattern. IBM is associated with marked morbidity as majority of patients eventually become wheelchair dependent with limited use of their hands and marked dysphagia. Furthermore, IBM mildly affects longevity with aspiration pneumonia and respiratory complications being the most common cause of death. On muscle biopsy, IBM is characterized by a peculiar combination of endomysial inflammation, rimmed vacuoles, and protein aggregation. These histopathological features are reflective of the complexity of underlying disease mechanisms. No pharmacological treatment is yet available for IBM. Monitoring for swallowing and respiratory complications, exercise, and addressing mobility issues are the mainstay of management. Further research is needed to better understand disease pathogenesis and identify novel therapeutic targets.

Survival and associated comorbidities in inclusion body myositis

OBJECTIVE

To evaluate survival and associated comorbidities in inclusion body myositis (IBM) in a population-based, case-control study.

METHODS

We utilized the expanded Rochester Epidemiology Project medical records-linkage system, including 27 counties in Minnesota and Wisconsin, to identify patients with IBM, other inflammatory myopathies (IIM), and age/sex-matched population-controls. We compared the frequency of various comorbidities and survival among groups.

RESULTS

We identified 50 IBM patients, 65 IIM controls and 294 population controls. Dysphagia was most common in IBM (64%) patients. The frequency of neurodegenerative disorders (dementia/parkinsonism) and solid cancers was not different between groups. Rheumatoid arthritis was the most common rheumatic disease in all groups. A total of 36% of IBM patients had a peripheral neuropathy, 6% had Sjögren's syndrome and 10% had a haematologic malignancy. T-cell large granular lymphocytic leukaemia was only observed in the IBM group. None of the IBM patients had hepatitis B or C, or HIV. IBM patients were 2.7 times more likely to have peripheral neuropathy, 6.2 times more likely to have Sjögren's syndrome and 3.9 times more likely to have a haematologic malignancy than population controls. IBM was associated with increased mortality, with a 10-year survival of 36% from index, compared with 67% in IIM and 59% in population controls. Respiratory failure or pneumonia (44%) was the most common cause of death.

CONCLUSIONS

IBM is associated with lower survival, and higher frequency of peripheral neuropathy, Sjögren's syndrome and haematologic malignancies than the general population. Close monitoring of IBM-related complications is warranted.

STAT3 and STAT5B Mutations in T/NK-Cell Chronic Lymphoproliferative Disorders of Large Granular Lymphocytes (LGL): Association with Disease Features

Simple Summary

STAT3 and STAT5B mutations have been identified in a subset of T and NK large granular lymphocytic leukemia (T/NK-LGLL). The aim of our study was to evaluate the frequency and type of these mutations in all different subtypes of T/NK-LGL expansions (n = 100 patients), as well as to analyze its association with biological and clinical features of the disease. We show for the first time that STAT3/5B mutations were present in all different T/NK-cell LGLL categories here studied; further, STAT3 mutations were associated with overall reduced counts of almost all normal residual populations of immune cells in blood, together with a shorter time-to-therapy vs. wild type T/NK-LGLL. These findings contribute to support the utility of the STAT3 mutation analysis for diagnostic and prognostic purposes in LGLL.

Abstract

STAT3 and STAT5B (STAT3/STAT5B) mutations are the most common mutations in T-cell large granular lymphocytic leukemia (T-LGLL) and chronic lymphoproliferative disorders of NK cells (CLPD-NK), but their clinical impact remains unknown. We investigated the frequency and type of STAT3/STAT5B mutations in FACS-sorted populations of expanded T/NK-LGL from 100 (82 clonal; 6 oligoclonal; 12 polyclonal) patients, and its relationship with disease features. Seventeen non-LGL T-CLPD patients and 628 age-matched healthy donors were analyzed as controls. STAT3 (n = 30) and STAT5B (n = 1) mutations were detected in 28/82 clonal T/NK-LGLL patients (34%), while absent (0/18, 0%) among oligoclonal/polyclonal LGL-lymphocytosis. Mutations were found across all diagnostic subgroups: TCD8⁺-LGLL, 36%; CLPD-NK, 38%; TCD4⁺-LGLL, 7%; Tαβ⁺DP-LGLL, 100%; Tαβ⁺DN-LGLL, 50%; Tγδ⁺-LGLL, 44%. STAT3-mutated T-LGLL/CLPD-NK showed overall reduced (p < 0.05) blood counts of most normal leukocyte subsets, with a higher rate (vs. nonmutated LGLL) of neutropenia (p = 0.04), severe neutropenia (p = 0.02), and cases requiring treatment (p = 0.0001), together with a shorter time-to-therapy (p = 0.0001), particularly in non-Y640F STAT3-mutated patients. These findings confirm and extend on previous observations about the high prevalence of STAT3 mutations across different subtypes of LGLL, and its association with a more marked decrease of all major blood-cell subsets and a shortened time-to-therapy.

T-cell clones of uncertain significance are highly prevalent and show close resemblance to T-cell large granular lymphocytic leukemia. Implications for laboratory diagnostics

Benign clonal T-cell expansions in reactive immune responses often complicate the laboratory diagnosis T-cell neoplasia. We recently introduced a novel flow cytometry assay to detect T-cell clones in blood and bone marrow, based on the identification of a monophasic T-cell receptor (TCR) β chain constant region-1 (TRBC1) expression pattern within a phenotypically distinct TCRαβ T-cell subset. In routine laboratory practice, T-cell clones of uncertain significance (T-CUS) were detected in 42 of 159 (26%) patients without T-cell malignancy, and in 3 of 24 (13%) healthy donors. Their phenotype (CD8⁺/CD4^-: 78%, CD4^-/CD8^-: 12%, CD4⁺/CD8⁺: 9%, or CD4⁺/CD8^-: 2%) closely resembled that of 26 cases of T-cell large granular lymphocytic leukemia (T-LGLL) studied similarly, except for a much smaller clone size (p < 0.0001), slightly brighter CD2 and CD7, and slightly dimmer CD3 expression (p < 0.05). T-CUS was not associated with age, gender, comorbidities, or peripheral blood counts. TCR-Vβ repertoire analysis confirmed the clonality of T-CUS, and identified additional clonotypic CD8-positive subsets when combined with TRBC1 analysis. We hereby report the phenotypic features and incidence of clonal T-cell subsets in patients with no demonstrable T-cell neoplasia, providing a framework for the differential interpretation of T-cell clones based on their size and phenotypic properties.

Flow Cytometry Applications in the Diagnosis of T/NK-Cell Lymphoproliferative Disorders

This article provides an overview of the role of flow cytometry in the diagnosis, prognosis, and follow-up of T and NK-cell lymphoproliferative disorders. For each category, we will briefly discuss the immunophenotypic features of normal T and NK cells, and address technical issues in flow cytometry, the approach to diagnosis in various contexts, pitfalls in interpretation, and its use in follow-up and post-therapy management. In addition to reviewing the diagnostic, prognostic, and therapeutic utility of flow cytometric immunophenotyping in several of specific T and NK cell entities, we will also cover some of the new immunophenotypic markers. Furthermore, we will touch upon incorporation of flow cytometry in the final diagnosis, including correlation with other ancillary tests. © 2019 International Clinical Cytometry Society.

Mutations in the signal transducer and activator of transcription family of genes in cancer

In recent years, it has become clear that members of the signal transducer and activator of transcription (STAT) family of genes play an important role in cancer. The STAT family consists of seven genes, STAT1‐4,STAT5A, STAT5B and STAT6, that are involved in regulating cellular proliferation, apoptosis, angiogenesis and the immune system response. Constitutive activation of STAT3, via mutational changes, is important in oncogenesis in both solid and hematopoietic cancers. In the case of hematopoietic neoplasms, STAT3 driver mutations have been described in T‐cell large granular lymphocytic (T‐LGL) leukemia and chronic natural killer lymphoproliferative disorders (CLPD‐NK) and are seen in 30%‐40% of T‐LGL leukemia patients. STAT5B is also mutated in T‐LGL leukemia and CLPD‐NK, but in a much smaller proportion. Here we review past and current research on STAT genes in hematopoietic and solid cancers with emphasis on STAT3 and STAT5B and their roles in the pathogenesis of hematopoietic malignancies, particularly T‐LGL leukemia and CLPD‐NK.

Diagnosis of chronic lymphoproliferative disorders by flow cytometry using four-color combinations for immunophenotyping: A proposal of the brazilian group of flow cytometry (GBCFLUX)

BACKGROUND

Multiparametric flow cytometry (MFC) is a powerful tool for the diagnosis of hematological malignancies and has been useful for the classification of chronic lymphoproliferative disorders (CLPD) according to the WHO criteria. Following the purposes of the Brazilian Group of Flow Cytometry (GBCFLUX), the aim of this report was to standardize the minimum requirements to achieve an accurate diagnosis in CLPDs, considering the different economic possibilities of the laboratories in our country. Most laboratories in Brazil work with 4-fluorescence flow cytometers, which is why the GBCFLUX CLPD Committee has proposed 4-color monoclonal antibody (MoAb) panels.

METHODS/RESULTS

Panels for screening and diagnosis in B, T and NK lymphoproliferative disorders were developed based on the normal differentiation pathways of these cells and the most frequent phenotypic aberrations. Important markers for prognosis and for minimal residual disease (MRD) evaluation were also included. The MoAb panels presented here were designed based on the diagnostic expertise of the participating laboratories and an extensive literature review.

CONCLUSION

The 4-color panels presented to aid in the diagnosis of lymphoproliferative neoplasms by GBCFLUX aim to provide clinical laboratories with a systematic, step-wise, cost-effective, and reproducible approach to obtain an accurate immunophenotypic diagnosis of the most frequent of these disorders. © 2016 International Clinical Cytometry Society.

Next-generation sequencing of acute myeloid leukemia identifies the significance of TP53, U2AF1, ASXL1, and TET2 mutations

We assessed the frequency and clinicopathologic significance of 19 genes currently identified as significantly mutated in myeloid neoplasms, RUNX1, ASXL1, TET2, CEBPA, IDH1, IDH2, DNMT3A, FLT3, NPM1, TP53, NRAS, EZH2, CBL, U2AF1, SF3B1, SRSF2, JAK2, CSF3R, and SETBP1, across 93 cases of acute myeloid leukemia (AML) using capture target enrichment and next-generation sequencing. Of these cases, 79% showed at least one nonsynonymous mutation, and cases of AML with recurrent genetic abnormalities showed a lower frequency of mutations versus AML with myelodysplasia-related changes (P<0.001). Mutational analysis further demonstrated that TP53 mutations are associated with complex karyotype AML, whereas ASXL1 and U2AF1 mutations are associated with AML with myelodysplasia-related changes. Furthermore, U2AF1 mutations were specifically associated with trilineage morphologic dysplasia. Univariate analysis demonstrated that U2AF1 and TP53 mutations are associated with absence of clinical remission, poor overall survival (OS), and poor disease-free survival (DFS; P<0.0001), whereas TET2 and ASXL1 mutations are associated with poor OS (P<0.03). In multivariate analysis, U2AF1 and TP53 mutations retained independent prognostic significance in OS and DFS, respectively. Our results demonstrate unique relationships between mutations in AML, clinicopathologic prognosis, subtype categorization, and morphologic dysplasia.

Indolent T-lymphoblastic proliferation with disseminated multinodal involvement and partial CD33 expression

Although indolent T-lymphoblastic proliferations (iT-LBP) are rare, this diagnosis should be excluded in any patient with an extrathymic proliferation of immature TdT+T cells. Unlike T-lymphoblastic leukemia/lymphoma, patients with iT-LBP do not require chemotherapy. We report a case of iT-LBP with disseminated multinodal involvement in an otherwise healthy 49-year-old woman. Multiple lymph node biopsies were performed over the course of several months demonstrating persistent and anatomically diffuse involvement. Over 18 months, and without therapy, she has remained healthy, and her lymphadenopathy significantly improved. No bone marrow or peripheral blood involvement was ever identified. Atypical T cells showed an immunophenotypic spectrum of T-cell antigen expression with partial CD33 on a subset of T cells detected by both flow cytometry and immunohistochemistry. Both T-cell clonality and Human Androgen Receptor Assay (HUMARA) studies, performed on lymph node biopsy specimens, were negative. This case represents the first detailed clinical, morphologic, molecular, and immunophenotypic description of disseminated multinodal involvement by nonclonal iT-LBP with partial CD33 expression on T cells.

Large B-cell lymphomas poor in B cells and rich in PD-1+ T cells can mimic T-cell lymphomas

OBJECTIVES

To characterize the clinicopathologic features of cases of large B-cell lymphomas, poor in B cells and densely rich in programmed cell death-1 (PD-1)+ reactive T cells, which can mimic T-cell lymphomas.

METHODS

A single-institute retrospective review of cases between 2010 and 2013 was performed.

RESULTS

Of 178 cases of large B-cell lymphomas, eight cases of large B-cell lymphomas poor in B cells and diffusely rich in sheets of PD-1+ T cells were identified. These cases either were initially misdiagnosed as a T-cell lymphoma or substantiated a broader differential diagnosis including a T-cell lymphoma. Five cases were T-cell histiocyte-rich large B-cell lymphomas, and three cases were diagnosed as large B-cell lymphomas rich in T cells. In three of these cases, a subset of the PD-1+ T cells showed either morphologic nuclear atypia or atypical expression of T-cell antigens on flow cytometry and/or immunohistochemistry.

CONCLUSIONS

Large B-cell lymphomas poor in B cells and rich in T cells can have diffuse sheets of reactive PD-1+ T cells, some with atypical morphologic and immunophenotypic features mimicking a T-cell lymphoma. Careful assessment of the immunoarchitecture and background inflammatory and stromal cells can prevent erroneous diagnoses in such cases.

E-cadherin is a specific marker for erythroid differentiation and has utility, in combination with CD117 and CD34, for enumerating myeloblasts in hematopoietic neoplasms

OBJECTIVES

E-cadherin, epithelial calcium-dependent cell adhesion protein, has been identified as a marker of immature erythroid precursors in recent years. However, the specificity of E-cadherin in bone marrow specimens for erythroblasts vs myeloblasts or other early hematopoietic precursors in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) has not been fully elucidated.

METHODS

We analyzed 105 cases of AML and MDS to evaluate the specificity of E-cadherin.

RESULTS

Of 84 cases of AML, including cases with megakaryocytic, erythroid, monocytic, and granulocytic differentiation, all five acute erythroleukemia cases were positive, as well as one case of megakaryoblastic leukemia that showed coexpression of glycophorin A. In addition, we demonstrate that a panel of three markers, E-cadherin, CD117, and CD34, is effective in identifying lineage-specific myeloblasts in cases of MDS where left-shifted erythroid hyperplasia may complicate morphologic assessment of myeloblasts.

CONCLUSIONS

In marrow specimens, E-cadherin is a useful marker for erythroid differentation.

Distinguishing T-cell Large Granular Lymphocytic Leukemia from Reactive Conditions: Laboratory Tools and Challenges in Their Use

This article focuses on the challenges of diagnosing T-cell large granular leukemia and distinguishing it from benign reactive conditions, as well as more aggressive neoplasms of cytotoxic lymphocytes. No single laboratory method is sufficient to make the diagnosis, but instead a combination of flow cytometry, genetic studies, and bone marrow immunohistochemistry must be used.

Expansion of a clonal CD8+CD57+ large granular lymphocyte population after autologous stem cell transplant in multiple myeloma

Clonal expansions of large granular lymphocytes (LGLs) have been identified in patients following stem cell transplants and may represent posttransplant LGL leukemias or reactive immune responses. To differentiate between these 2 possibilities, we assessed peripheral blood and bone marrow of patients with myeloma after autologous stem cell transplant. All patients examined shortly after autologous stem cell transplant had significant increases in the LGLs in the peripheral blood and bone marrow (71% of lymphocytes) as compared with controls (39%). This increase was detectable years after transplant. The LGLs had a reproducible immunophenotype of CD8+CD57+ T cells without phenotypic abnormalities in 19 of 20 patients. Sixty-five percent of the post-autologous stem cell transplant patients had clonal T-cell receptor gene rearrangements in the bone marrow, yet no patients had neutropenia or splenomegaly. Although the LGL expansions were clonal and persistent, the lack of clinical sequelae suggests the clonal LGL expansion is a reactive, potentially beneficial, immune response to autologous stem cell transplant.

The differential diagnosis and bone marrow evaluation of new-onset pancytopenia

New-onset pancytopenia can be caused by a wide variety of etiologies, leading to a diagnostic dilemma. These etiologies range from congenital bone marrow failure to marrow space-occupying lesions, infection, and peripheral destruction, to name a few. Bone marrow examination, in addition to a detailed clinical history, is often required for an accurate diagnosis. The purpose of this review is to provide a brief overview of many of the causes of new-onset pancytopenia in adults and children, with emphasis on bone marrow findings and recommendations of additional testing and clinical evaluation when needed, with the overall aim of aiding the pathologist's role as a consultant to the patient's treating physician.

Molecular Pathology of Malignant Lymphoma

This review focuses on practical uses of molecular testing in mature B-cell and T-cell lymphomas with a focus on those lymphomas in which molecular testing is common. Clinical findings, histology, and biomarkers, as well as diagnostic and prognostic predictive value and practical applications of molecular testing for mature B- and T-cell lymphomas are presented.