Morice, William G.

Abstract Objectives Large granular lymphocytic leukemia (LGLL) represents a rare neoplasm of mature T cells or natural killer (NK) cells, with an indolent clinical course. Diagnosing LGLL can be challenging because of overlapping features with reactive processes and other mimickers. Methods By presenting 2 challenging cases, we elucidate the differentiation of LGLL from its mimics and highlight potential diagnostic pitfalls. A comprehensive review of the clinicopathologic features of LGLL was conducted. Results Large granular lymphocytic leukemia displays a diverse spectrum of clinical presentations, morphologies, flow cytometric immunophenotypes, and molecular profiles. These features are also encountered in reactive conditions, T-cell clones of uncertain significance, and NK cell clones of uncertain significance. Conclusions In light of the intricate diagnostic landscape, LGLL workup must encompass clinical, morphologic, immunophenotypic, clonal, and molecular findings. Meeting major and minor diagnostic criteria is imperative for the accurate diagnosis of LGLL.

Abstract Tγδ large granular lymphocyte leukemia (LGLL) is a rare variant of T-cell LGLL (T-LGLL) that has been less investigated as compared with the more frequent Tαβ LGLL, particularly in terms of frequency of STAT3 and STAT5b mutations. In this study, we characterized the clinical and biological features of 137 patients affected by Tγδ LGLL; data were retrospectively collected from 1997 to 2020 at 8 referral centers. Neutropenia and anemia were the most relevant clinical features, being present in 54.2% and 49.6% of cases, respectively, including severe neutropenia and anemia in ∼20% of cases each. Among the various treatments, cyclosporine A was shown to provide the best response rates. DNA samples of 97 and 94 cases were available for STAT3 and STAT5b mutation analysis, with 38.1% and 4.2% of cases being mutated, respectively. Clinical and biological features of our series of Tγδ cases were also compared with a recently published Tαβ cohort including 129 cases. Though no differences in STAT3 and STAT5b mutational frequency were found, Tγδ cases more frequently presented with neutropenia (P = .0161), anemia (P < .0001), severe anemia (P = .0065), and thrombocytopenia (P = .0187). Moreover, Vδ2− cases displayed higher frequency of symptomatic disease. Overall, Tγδ cases displayed reduced survival with respect to Tαβ cases (P = .0017). Although there was no difference in STAT3 mutation frequency, our results showed that Tγδ LGLL represents a subset of T-LGLL characterized by more frequent symptoms and reduced survival as compared with Tαβ LGLL.

Abstract 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.

Durable T cell responses to SARS-CoV-2 antigens after infection or vaccination improve immune-mediated viral clearance. To date, population-based surveys of COVID-19 adaptive immunity have focused on testing for IgG antibodies that bind spike protein and/or neutralize the virus. Deployment of existing methods for measuring T cell immunity could provide a more complete profile of immune status, informing public health policies and interventions.

Abstract Context. —In comparison to αβ T cells, little is known about the immunophenotype of healthy peripheral blood γδ T cells or about conditions associated with expansion of this usually minor T-cell subset. Objective. —To study the immunophenotype of increased nonneoplastic peripheral blood γδ T cells and to determine clinical conditions associated with this laboratory finding. Design. —Flow cytometric T-cell phenotyping studies performed on 352 consecutive peripheral blood specimens were reviewed, and 62 cases (18%) in which γδ T cells comprised either more than 5% of the total lymphocytes or had an absolute count of more than 200 cells per μL or both, were studied further. Clinical data were available from 36 cases. Results. —The γδ T cells often had an immunophenotype distinct from the αβ T cells, with differences in CD5 expression as the most common (n = 17), followed by differences in CD3 (n = 6) and CD7 (n = 3). CD16 coexpression by the γδ T cells was also frequent (n = 20). In 28 (78%) of 36 cases, there were one or more associated conditions: infection/inflammatory disease (n = 18), autoimmune disease (n = 9), lymphoproliferative disorder (n = 6), and splenectomy (n = 3). Conclusions. —Circulating γδ T cells are immunophenotypically distinct from αβ T cells, and mild increases in these cells are not uncommon and may be associated with immune system activation and splenectomy. Recognition of this phenomenon is important because reactive γδ T cells can exhibit distinctive immunophenotypic features that are also encountered in neoplastic conditions, such as T-cell large granular lymphocytic leukemia.

Abstract Objectives The diagnosis of T-cell large granular lymphocytic leukemia (T-LGLL) is challenging because of overlapping immunophenotypic features with reactive T cells and limitations of T-cell clonality assays. We studied whether adding an antibody against T-cell receptor β constant region 1 (TRBC1) to a comprehensive flow cytometry panel could facilitate the diagnosis of T-LGLL. Methods We added TRBC1 antibody to the standard T-cell and natural killer (NK) cell panel to assess T-cell clonality in 56 T-LGLLs and 34 reactive lymphocytoses. In addition, 20 chronic lymphoproliferative disorder of NK cells (CLPD-NKs) and 10 reactive NK-cell lymphocytoses were analyzed. Results Clonal T cells were detected in all available T-LGLLs by monotypic TRBC1 expression and clonal/equivocal T-cell receptor gene rearrangement (TCGR) studies, compared with only 27% of T-LGLLs by killer-cell immunoglobulin-like receptor (KIR) restriction. Overall, 85% of T-LGLLs had a blood tumor burden greater than 500 cells/µL. Thirty-four reactive cases showed polytypic TRBC1 expression, except for 5 that revealed small T-cell clones of uncertain significance. All CLPD-NKs showed expected clonal KIR expression and negative TRBC1 expression. Conclusions Addition of TRBC1 antibody to the routine flow cytometry assay could replace the TCGR molecular study and KIR flow cytometric analysis to assess clonality, simplifying the diagnosis of T-LGLL.

Temporal inference from laboratory testing results and triangulation with clinical outcomes extracted from unstructured electronic health record (EHR) provider notes is integral to advancing precision medicine. Here, we studied 246 SARS-CoV-2 PCR-positive (COVID pos ) patients and propensity-matched 2460 SARS-CoV-2 PCR-negative (COVID neg ) patients subjected to around 700,000 lab tests cumulatively across 194 assays. Compared to COVID neg patients at the time of diagnostic testing, COVID pos patients tended to have higher plasma fibrinogen levels and lower platelet counts. However, as the infection evolves, COVID pos patients distinctively show declining fibrinogen, increasing platelet counts, and lower white blood cell counts. Augmented curation of EHRs suggests that only a minority of COVID pos patients develop thromboembolism, and rarely, disseminated intravascular coagulopathy (DIC), with patients generally not displaying platelet reductions typical of consumptive coagulopathies. These temporal trends provide fine-grained resolution into COVID-19 associated coagulopathy (CAC) and set the stage for personalizing thromboprophylaxis.