Erythroid proliferations in myeloid neoplasms

Flow Cytometry Analysis Versus E-Cadherin Immunohistochemistry for the Diagnosis of Pure Erythroid Leukemia: A Case Report

Pure erythroid leukemia (PEL) is a rare form of acute myeloid leukemia characterized by the neoplastic proliferation of erythroblasts. PEL is associated with inferior survival outcomes, particularly among patients harboring complex karyotype abnormalities. In this case, we present a 21-year-old Sudanese man who presented to our ER with a two-week history of fever, shortness of breath, fatigue, and exercise intolerance. He had no significant personal medical history or family history of malignancy. A bone marrow biopsy revealed hypercellularity and infiltration by cells with an immature appearance. A flow cytometry (FC) analysis of the bone marrow aspirate revealed that approximately 21% of the total nucleated cells were negative for CD45 and positive for CD71, glycophorin A, and CD36 but negative for myeloperoxidase (MPO), CD33, CD13, CD61, CD41, and other lymphoid and myeloid markers. Consistent with the microscopic analysis, <1% of the total cells were identified as CD34/CD13/CD117-positive myeloblasts. Notably, all stains (CD45, MPO, CD34, CD163, CD61, glycophorin A) were negative except E-cadherin, which positively stained >80% of the cells. Our findings suggested a differential diagnosis that included erythroid leukemia and myelodysplastic syndrome (MDS). The morphological, FC, immunohistochemistry, and cytogenetic findings strongly supported a diagnosis of PEL.

Normal and pathological erythropoiesis in adults: from gene regulation to targeted treatment concepts

Pathological erythropoiesis with consequent anemia is a leading cause of symptomatic morbidity in internal medicine. The etiologies of anemia are complex and include reactive as well as neoplastic conditions. Clonal expansion of erythroid cells in the bone marrow may result in peripheral erythrocytosis and polycythemia but can also result in anemia when clonal cells are dysplastic and have a maturation arrest that leads to apoptosis and hinders migration, a constellation typically seen in the myelodysplastic syndromes. Rarely, clonal expansion of immature erythroid blasts results in a clinical picture resembling erythroid leukemia. Although several mechanisms underlying normal and abnormal erythropoiesis and the pathogenesis of related disorders have been deciphered in recent years, little is known about specific markers and targets through which prognosis and therapy could be improved in anemic or polycythemic patients. In order to discuss new markers, targets and novel therapeutic approaches in erythroid disorders and the related pathologies, a workshop was organized in Vienna in April 2017. The outcomes of this workshop are summarized in this review, which includes a discussion of new diagnostic and prognostic markers, the updated WHO classification, and an overview of new drugs used to stimulate or to interfere with erythropoiesis in various neoplastic and reactive conditions. The use and usefulness of established and novel erythropoiesis-stimulating agents for various indications, including myelodysplastic syndromes and other neoplasms, are also discussed.

De novo pure erythroid leukemia: refining the clinicopathologic and cytogenetic characteristics of a rare entity

Per the revised fourth edition World Health Organization classification of acute myeloid leukemia, pure erythroid leukemia is now the sole type of acute erythroid leukemia. The diagnosis of this rare entity is often challenging and the cytologic overlap with non-neoplastic (eg, megaloblastic anemia) and neoplastic entities (eg, other types of acute leukemia and non-hematopoietic malignancies) warrants a significant degree of clinical, laboratory, immunophenotypic, and genetic investigation. Given the limited number of reports of this rare and diagnostically challenging entity, we report detailed clinicopathologic characteristics from 15 patients, the largest series thus far, of primary de novo pure erythroid leukemia to provide further diagnostic insights into this entity and reveal strategies for making the diagnosis. We found that de novo pure erythroid leukemia is a disease of adults (median age 68 years), exhibits a striking male predominance, is universally associated with an abnormal karyotype and has an exceedingly poor overall median survival of 1.4 months. Given the general inability of immunophenotypic markers to discriminate neoplastic from non-neoplastic erythroid proliferations, key features identified in this study to help establish the diagnosis of pure erythroid leukemia and exclude mimickers include circulating pronormoblasts, clear-cut dysplasia in erythroid, granulocytic, and/or megakaryocytic lineage, utilization of a broad immunophenotypic panel, TP53 immunohistochemical positivity, and identification of a complex, often highly complex, karyotype. Given the gravity of a diagnosis of de novo pure erythroid leukemia, it should be rendered with utmost confidence.

The uniqueness of morphological features of pure erythroid leukemia in myeloid neoplasm with erythroid predominance: A reassessment using criteria revised in the 2016 World Health Organization classification

We reviewed 97 consecutive cases of myeloid neoplasm with erythroid predominance (MN-EP) between 2000 and 2015. Following 2016 WHO classification, MN-EP patients were classified into four groups. Eight pure erythroid leukemia (PEL) (including t-MN and AML-MRC morphologically fulfilled criteria for PEL) patients had dismal outcomes (median OS: 1 month) and showed more bone marrow fibrosis, worse performance status (PS) and higher serum lactate dehydrogenase (LDH) at diagnosis than the other groups. In the univariate analysis, risks of death in MN-EP patients included the morphologic features of PEL, very poor cytogenetic risk by IPSS-R, bone marrow fibrosis, leukocytosis, anemia, hypoalbuminemia, high LDH, and poor PS. In the multivariate analysis, independent predictors of death were morphologic features of PEL (adjusted hazards ratio [HR] 3.48, 95% confidence interval [CI] 1.24–9.74, p = 0.018), very poor cytogenetic risk by IPSS-R (adjusted HR 2.73, 95% CI 1.22–6.10, p = 0.015), hypoalbuminemia (< 3.7 g/dl) (adjusted HR 2.33, 95% CI 1.10–4.91, p = 0.026) and high serum LDH (≥ 250 U/L) (adjusted HR 2.36, 95% CI 1.28–4.36, p = 0.006). Poor or unfavorable risk in different cytogenetic risk systems independently predicted death and UKMRC-R was the best model.

Pure Erythroid Leukemia Mimicking Ewing Sarcoma/Primitive Neuroectodermal Tumor in an Infant

Pure erythroid leukemia (PEL) is a rare type of acute myeloid leukemia (AML) with a very aggressive clinical course. Presentation as a myeloid/erythroid sarcoma is exceedingly rare. We describe an infantile PEL presenting as a multifocal myeloid sarcoma, clinically and pathologically mimicking Ewing sarcoma/PNET family of tumors. The patient died 8 weeks after the initial presentation due to widespread disease. Our case shows that PEL needs to be considered in the differential diagnosis of small round blue cell tumors in infancy. A meticulous workup including immunohistochemistry, flow cytometry, molecular, and cytogenetic studies was required to reach the diagnosis.

Acute Erythroleukemias, Acute Megakaryoblastic Leukemias, and Reactive Mimics: A Guide to a Number of Perplexing Entities

OBJECTIVES

At the 2013 Society for Hematopathology/European Association for Hematopathology Workshop, 36 cases were submitted to the session that covered acute erythroid leukemia (AEL), acute megakaryoblastic leukemia (AMKL), and reactive mimics.

METHODS

Cases were reviewed by the session chairs and workshop panel to reach a consensus diagnosis.

RESULTS

For acute erythroleukemia, erythroid/myeloid type, discussion acknowledged overlapping features between AEL and myelodysplastic syndromes. Cases submitted as pure erythroid leukemia had distinctive morphology and immunophenotype, complex karyotypes, and aggressive clinical behavior, illustrating certain diagnostic features not currently captured by the current World Health Organization (WHO) definition. In Down syndrome, there were striking similarities between transient abnormal myelopoiesis and AMKL. Most cases of AMKL in adults would be classified as acute myeloid leukemia with myelodysplasia-related changes according to the WHO classification, but this approach deemphasizes their unique clinical, morphologic, and immunophenotypic features.

CONCLUSIONS

The broad spectrum of cases illustrated the difficulties and complex issues involved in establishing a diagnosis of these entities and the need for better disease definitions.

Global transcriptome analyses of human and murine terminal erythroid differentiation

We recently developed fluorescence-activated cell sorting (FACS)-based methods to purify morphologically and functionally discrete populations of cells, each representing specific stages of terminal erythroid differentiation. We used these techniques to obtain pure populations of both human and murine erythroblasts at distinct developmental stages. RNA was prepared from these cells and subjected to RNA sequencing analyses, creating unbiased, stage-specific transcriptomes. Tight clustering of transcriptomes from differing stages, even between biologically different replicates, validated the utility of the FACS-based assays. Bioinformatic analyses revealed that there were marked differences between differentiation stages, with both shared and dissimilar gene expression profiles defining each stage within transcriptional space. There were vast temporal changes in gene expression across the differentiation stages, with each stage exhibiting unique transcriptomes. Clustering and network analyses revealed that varying stage-specific patterns of expression observed across differentiation were enriched for genes of differing function. Numerous differences were present between human and murine transcriptomes, with significant variation in the global patterns of gene expression. These data provide a significant resource for studies of normal and perturbed erythropoiesis, allowing a deeper understanding of mechanisms of erythroid development in various inherited and acquired erythroid disorders.

Erythroleukemia and Its Differential Diagnosis

Acute erythroid leukemias encompass 2 main subtypes: acute erythroleukemia (erythroid/myeloid subtype) and pure erythroid leukemia. This article reviews the main clinicopathologic features of the acute erythroid leukemias and the criteria used to diagnose them. In this article, the differential diagnosis between acute erythroid leukemias and their mimics is discussed and helpful morphologic clues and diagnostic tests that help arrive at the correct diagnosis are provided. The appropriate application of diagnostic criteria, including ancillary testing, such as immunophenotyping, cytogenetics, and molecular genetic testing, is essential to categorize bone marrow erythroid proliferations.

The potential role of cell penetrating peptides in the intracellular delivery of proteins for therapy of erythroid related disorders

The erythroid related disorders (ERDs) represent a large group of hematological diseases, which in most cases are attributed either to the deficiency or malfunction of biosynthetic enzymes or oxygen transport proteins. Current treatments for these disorders include histo-compatible erythrocyte transfusions or allogeneic hematopoietic stem cell (HSC) transplantation. Gene therapy delivered via suitable viral vectors or genetically modified HSCs have been under way. Protein Transduction Domain (PTD) technology has allowed the production and intracellular delivery of recombinant therapeutic proteins, bearing Cell Penetrating Peptides (CPPs), into a variety of mammalian cells. Remarkable progress in the field of protein transduction leads to the development of novel protein therapeutics (CPP-mediated PTs) for the treatment of monogenetic and/or metabolic disorders. The “concept” developed in this paper is the intracellular protein delivery made possible via the PTD technology as a novel therapeutic intervention for treatment of ERDs. This can be achieved via four stages including: (i) the production of genetically engineered human CPP-mediated PT of interest, since the corresponding native protein either is missing or is mutated in the erythroid progenitor cell (ErPCs) or mature erythrocytes of patients; (ii) isolation of target cells from the peripheral blood of the selected patients; (iii) ex vivo transduction of cells with the CPP-mediated PT of interest; and (iv) re-administration of the successfully transduced cells back into the same patients.