Reporting blast percentage for response assessment in acute leukemias: recommendations from an EHA/ELN expert panel.

Evaluation of bone marrow blast percentage is paramount to response criteria in acute leukemias. There is an identified need within the framework of updated laboratory practices to reduce inconsistencies in methodologies used by clinical laboratories to report blast values and clarify aspects of reporting. Representatives from international specialised working groups including the European Hematology Association (EHA) Diagnosis in Hematological Diseases Specialised Working Group and the European LeukemiaNet (ELN) produced consensus guidance for harmonised blast assessment to define response categories in acute leukemic patients.

Immunophenotypic, cytogenetic, and mutational features of chronic lymphocytic leukemia/small lymphocytic lymphoma with atypical immunophenotype.

Flow cytometric analysis plays an important role in the diagnosis of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Most CLL cases show a typical immunophenotype characterized by the expression of CD5, CD23, CD43, ROR1, and CD200, along with dim expression of B-cell markers. However, some show an atypical immunophenotype.

Optical Genome Mapping in Myelodysplastic Syndromes: Clinical Value and Limitations Derived from a Cohort of 236 Patients.

Identification of cytogenetic abnormalities is critical for the classification and risk stratification of myelodysplastic syndromes (MDS). Optical genome mapping (OGM) is an emerging cytogenomic platform that enables high-resolution genome-wide cytogenetic analysis. We analyzed bone marrow specimens of 236 MDS patients, 149 newly diagnosed and 87 with relapsed/refractory disease, using OGM, conventional karyotyping and next-generation sequencing analysis.

Erythroid-predominant myelodysplastic neoplasms exhibit a distinct genomic landscape with poor outcomes after venetoclax-based therapy.

Erythroid differentiation confers BCL-XL dependence and venetoclax resistance in acute myeloid leukemia (AML). However, whether myelodysplastic neoplasms (MDS) with erythroid predominance (EP), defined by ≥50% erythroid bone marrow elements, have distinct biology and drug sensitivities remains unknown. To study this, we evaluated an MDS patient cohort (n = 371) and showed that EP MDS (n = 67, 18%) are characterized by higher TP53 (multihit TP53: 36% vs 17%, p = 0.

Blood- and bone marrow-based mature T-cell and natural killer cell leukemias and lymphomas: a summary in the series of the 2023 SH/EAHP Workshop.

This session included 51 cases submitted to the workshop "Progress in T- and NK-cell Lymphomas and Leukemias" by the Society for Hematopathology and European Association for Haematopathology under "Blood/Bone Marrow-Based Mature T- and NK-Cell Leukemias/Lymphomas" or "T/NK-cell neoplasms with a Leukemic Presentation." Entities encompassed T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia (LGLL), natural killer (NK)-LGLL/chronic lymphoproliferative disorder of NK cells, adult T-cell leukemia/lymphoma, aggressive NK-cell leukemia, and their mimics. Submitted cases illustrated classic and variant morphology, immunophenotype, and clinical features; the overlaps with reactive T-cell /NK-cell lymphoproliferations; and challenges in differentiating these entities from other T-cell/NK-cell neoplasms with a leukemic presentation.

Technical and Clinical Validity of Assessing Measurable Residual Disease by Multicolor Flow Cytometry in an Unselected Acute Myeloid Leukemia Patient Cohort.

Context.—: Following the validation of a multicolor flow cytometry (MFC) assay for measurable residual disease (MRD) in acute myeloid leukemia (AML), this study examines its clinical applicability.

Objective.

Low CD25 in ALK+ Anaplastic Large Cell Lymphoma Is Associated with Older Age, Thrombocytopenia, and Increased Expression of Surface CD3 and CD8.

Background/objectives: Anaplastic lymphoma kinase (ALK)-positive (+) anaplastic large cell lymphoma (ALCL) is known to express CD25, but its significance has not been well studied.

Methods: In the present study, we identified 54 ALK+ ALCL patients with CD25 results available and investigated the significance of CD25 expression levels.

Results: Forty-two (78%) cases had high CD25 expressions, whereas low CD25 expressions were found in 12 (22%) cases.

A Case of Cryptic CBFB::MYH11 Acute Myeloid Leukemia With Noncanonical Breakpoints Detected by Optical Genome Mapping.

Accurate and timely detection of clinically relevant genetic abnormalities, such as CBFB::MYH11 or inversion(16) [inv(16)], is critical for the diagnosis and management of patients with acute myeloid leukemia (AML). Notably, CBFB::MYH11 is a disease-defining mutation in AML and is associated with a favorable prognosis. The current standard-of-care workup, which includes a combination of conventional G-banding karyotyping, fluorescence in situ hybridization (FISH), and/or reverse-transcriptase PCR, poses challenges in detecting variant CBFB::MYH11 translocations.

Acute lymphoblastic leukaemia with T- and B-lineage defining markers.

In acute lymphoblastic leukaemia (ALL), cytoplasmic CD3 (cCD3) is a defining marker for T-lineage, and CD19 plus additional B-cell marker(s) for B-lineage. We identified 23 ALL cases in which the lymphoblasts expressed both cCD3 and CD19, making lineage assignment challenging. These cases represented approximately 10% of cCD3+ ALL and expressed a median of two additional B-cell markers other than CD19, including CD79a (76%), CD22 (22%), PAX5 (57%) and CD10 (44%).

BCL11B helps to define T-lineage in lymphomas/leukaemias with a mixed/ambiguous immunophenotype.

BCL11B is a pan-T-cell transcription factor that plays a pivotal role in guiding T-cell differentiation and maturation. BCL11B is lineage specific, and its expression is confined to T cells; B, NK ​and myeloid cells are usually negative. In this study, we aim to explore the value of BCL11B in the diagnosis and differential diagnosis of lymphomas/leukaemias exhibiting an ambiguous immunophenotype or which simultaneously express both T- and B-cell markers.

Concurrent Bone Marrow Acute Undifferentiated Leukemia and Mediastinal T-Lymphoblastic Lymphoma With Identical Fusion and and Mutations.

Acute undifferentiated leukemia (AUL) is a rare hematologic malignancy lacking lineage-specific markers. Concurrent, clonally related AUL and T-lymphoblastic lymphoma (T-LBL) has not been reported previously. Here we describe a patient who was diagnosed with AUL in the bone marrow and T-LBL in the mediastinum after a thorough immunophenotyping by flow cytometry and immunohistochemistry.

Cryptic Fusion Due to Insertion into in a Patient with Acute Monoblastic Leukemia.

Background: rearrangements occur in ~10% of acute myeloid leukemia (AML) cases and are critical for classification, risk stratification, and use of targeted therapy. However, insertions involving the gene can evade detection using chromosomal analysis and/or fluorescence in situ hybridization (FISH).

Methods: We present a case of a 22-year-old woman with acute monoblastic leukemia harboring a cryptic fusion identified by RNA sequencing.

Long term results of venetoclax combined with FLAG-IDA induction and consolidation for newly diagnosed and relapsed or refractory acute myeloid leukemia.

Intensive chemotherapy remains the standard for newly diagnosed (ND) acute myeloid leukemia (AML); however, relapse risk remains high. Additionally, most patients with relapsed/refractory (RR) AML have poor outcomes. We report the long-term experience of 138 patients, 77 ND and 61 RR, treated with FLAG-IDA in combination with venetoclax.

Clinical, immunophenotypic, and genomic findings of acute myeloid leukemia with RAM immunophenotype: Comparison with other CD56-positive acute leukemias.

Background: Acute myeloid leukemia (AML) with RAM immunophenotype is a newly recognized high-risk AML immunophenotypic subcategory characterized by blasts with bright expression of CD56 and weak to absent expression of CD45, HLA-DR, and CD38, as first described by the Children's Oncology Group (COG). The relationship between AML-RAM and other CD56-positive acute leukemias is unclear. The goal of this study is to characterize the clinicopathological characteristics of AML with RAM phenotype and compare them with other CD56 co-expressing acute leukemias.

Diffuse Large B-Cell Lymphoma/High-Grade B-Cell Lymphoma With MYC and BCL6 Rearrangements: A Study of 60 Cases.

Classification of cases of diffuse large B-cell lymphoma (DLBCL)/high-grade B-cell lymphoma (HGBL) with MYC and BCL6 rearrangements, referred to here as BCL6 double-hit lymphoma (DHL), is controversial. We assessed 60 cases of BCL6-DHL and compared this cohort to 224 cases of DHL with MYC and BCL2 rearrangements (BCL2-DHL) and 217 cases of DLBCL not otherwise specified. Compared with the DLBCL cohort, patients with BCL6-DHL had more aggressive clinical features such as frequent extranodal involvement, high-stage disease, a high International Prognostic Index score, and an elevated serum lactate dehydrogenase level (P < .

The Significance of Detecting an Unusual Myeloblast Immunophenotype in a Presumptive Clinical Diagnosis of Myelodysplastic Syndromes.

Context.—: Blasts in myelodysplastic syndromes (MDSs) typically have a primitive myeloid immunophenotype (CD34+CD117+CD13+CD33+HLA-DR+). On rare occasions, blasts were found to be CD34 negative or minimally expressed in a presumptive MDS.

Application of flow cytometry immunophenotypic analysis for the diagnosis of mature B-cell lymphomas/leukemias.

Flow cytometry immunophenotyping (FCI) is an important and indispensable tool in the diagnosis of mature B-cell lymphomas/leukemias, particularly for small fine needle aspiration and needle core biopsy specimens which are becoming increasingly popular for diagnostic purposes. FCI has several advantages. Given its multiparametric nature, FCI can analyze the expression of multiple antigens simultaneously on the same cell of interest, qualitatively and quantitively.

Impact of measurable residual disease clearance kinetics in patients with AML undergoing intensive chemotherapy.

The prognostic impact of measurable residual disease (MRD) in acute myeloid leukemia (AML) is unequivocal; however, the optimal time point for achieving undetectable MRD is unclear. We retrospectively studied patients with newly diagnosed (ND) AML who achieved remission with frontline intensive chemotherapy and had MRD assessed by flow cytometry after induction (time point 1 [TP1]) and after cycles 2 or 3 (TP2). Cases were grouped into MRD negative (Neg)/Neg, positive (Pos)/Neg, or Pos/Pos at TP1 and TP2, respectively.

Case Report: Multidisciplinary management of a patient with indolent systemic mastocytosis and refractory symptoms.

Systemic mastocytosis (SM) is a rare hematologic condition characterized by the proliferation and accumulation in tissue of clonal mast cells in multiple organ systems. The release of mast cell mediators in the indolent disease type and the predominant mast cell infiltration of tissues in advanced disease contribute to the heterogeneous clinical presentation. The disease driver in >90% of adult cases is an activating mutation, with D816V being the most frequent.

Flow cytometric immunophenotypic features of acute myeloid leukemia with mast cell differentiation.

Objectives: Acute myeloid leukemia (AML) with mast cell (MC) differentiation was recently described as an aggressive subgroup of AML cases. The objectives of this study were to assess the flow cytometric immunophenotypic features of AML-MC cases.

Methods: We characterized the immunophenotypic features of 21 AML-MC cases by flow cytometry and compared them to 20 reactive/regenerating bone marrow specimens.