Comparison of genetic and clinical aspects in patients with acute myeloid leukemia and myelodysplastic syndromes all with more than 50% of bone marrow erythropoietic cells

NPM1-Mutated Myeloid Neoplasms with <20% Blasts: A Really Distinct Clinico-Pathologic Entity?

Nucleophosmin (NPM1) gene mutations rarely occur in non-acute myeloid neoplasms (MNs) with <20% blasts. Among nearly 10,000 patients investigated so far, molecular analyses documented NPM1 mutations in around 2% of myelodysplastic syndrome (MDS) cases, mainly belonging to MDS with excess of blasts, and 3% of myelodysplastic/myeloproliferative neoplasm (MDS/MPN) cases, prevalently classified as chronic myelomonocytic leukemia. These uncommon malignancies are associated with an aggressive clinical course, relatively rapid progression to overt acute myeloid leukemia (AML) and poor survival outcomes, raising controversies on their classification as distinct clinico-pathologic entities. Furthermore, fit patients with NPM1-mutated MNs with <20% blasts could benefit most from upfront intensive chemotherapy for AML rather than from moderate intensity MDS-directed therapies, although no firm conclusion can currently be drawn on best therapeutic approaches, due to the limited available data, obtained from small and mainly retrospective series. Caution is also suggested in definitely diagnosing NPM1-mutated MNs with blast count <20%, since NPM1-mutated AML cases frequently present dysplastic features and multilineage bone marrow cells showing abnormal cytoplasmic NPM1 protein delocalization by immunohistochemical staining, therefore belonging to NPM1-mutated clone regardless of blast morphology. Further prospective studies are warranted to definitely assess whether NPM1 mutations may become sufficient to diagnose AML, irrespective of blast percentage.

The ParaHox gene Cdx4 induces acute erythroid leukemia in mice

Acute erythroid leukemia (AEL) is a rare and aggressive form of acute leukemia, the biology of which remains poorly understood. Here we demonstrate that the ParaHox gene CDX4 is expressed in patients with acute erythroid leukemia, and that aberrant expression of Cdx4 induced homogenously a transplantable acute erythroid leukemia in mice. Gene expression analyses demonstrated upregulation of genes involved in stemness and leukemogenesis, with parallel downregulation of target genes of Gata1 and Gata2 responsible for erythroid differentiation. Cdx4 induced a proteomic profile that overlapped with a cluster of proteins previously defined to represent the most primitive human erythroid progenitors. Whole-exome sequencing of diseased mice identified recurrent mutations significantly enriched for transcription factors involved in erythroid lineage specification, as well as TP53 target genes partly identical to the ones reported in patients with AEL. In summary, our data indicate that Cdx4 is able to induce stemness and inhibit terminal erythroid differentiation, leading to the development of AEL in association with co-occurring mutations.

Upregulation of Glutamic-Oxaloacetic Transaminase 1 Predicts Poor Prognosis in Acute Myeloid Leukemia

One of the key features of acute myeloid leukemia (AML), a group of very aggressive myeloid malignancies, is their strikingly heterogenous outcomes. Accurate biomarkers are needed to improve prognostic assessment. Glutamate oxaloacetate transaminase 1 (GOT1) is essential for cell proliferation and apoptosis by regulating cell's metabolic dependency on glucose. It is unclear whether the expression level of GOT1 has clinical implications in AML. Therefore, we analyzed the data of 155 AML patients with GOT1 expression information from The Cancer Genome Atlas (TCGA) database. Among them, 84 patients were treated with chemotherapy alone, while 71 received allogeneic hematopoietic stem cell transplantation (allo-HSCT). In both treatment groups, high GOT1 expression was associated with shorter event-free survival (EFS) and overall survival (OS) (all P < 0.05). Multivariate analysis identified several independent risk factors for both EFS and OS in the chemotherapy-only group, including high GOT1 expression, age ≥60 years, white blood cell count ≥15 × 10⁹/L, bone marrow blasts ≥70%, and DNMT3A, RUNX1 or TP53 mutations (all P < 0.05); but in the allo-HSCT group, the only independent risk factor for survival was high GOT1 expression (P < 0.05 for both EFS and OS). Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the genes related to GOT1 expression were mainly concentrated in “hematopoietic cell lineage” and “leukocyte transendothelial migration” signaling pathways. Collectively, GOT1 expression may be a useful prognostic indicator in AML, especially in patients who have undergone allo-HSCT.

Prognostic role of SCAMP family in acute myeloid leukemia

Acute myeloid leukemia (AML) is a malignant disease of myeloid hematopoietic stem or progenitor cells characterized by abnormal proliferation of primary and immature myeloid cells in bone marrow and peripheral blood. Gene mutation and expression profiles can be used as prognosis predictors for different prognostic subgroups. Secretory carrier-associated membrane proteins (SCAMPs) are a multigenic family with five members and act as cell surface vectors in the post-Golgi recycling pathways in mammals. Nevertheless, the prognostic and clinical influence of SCAMP family has hardly ever been illustrated in AML. In our study, expression patterns of SCAMP family (SCAMP1-5) were analyzed in 155 AML patients which were extracted from the Cancer Genome Atlas database. In chemotherapy, only subgroup, higher SCAMP1 level was significantly associated with longer EFS and OS (all P = 0.002), and SCAMP1 was confirmed to be an independent favorable factor in un-transplanted patients by Multivariate analysis (all P < 0.05). Nevertheless, in the allogeneic hematopoietic stem cell transplantation (allo-HSCT) treatment subgroup, none of the SCAMP genes had any effect on the clinical survival. Our study found that high expression level of SCAMP1 is a favorable prognostic factor in AML, but allo-HSCT may neutralize its prognostic effect.

Up-regulation of DDIT4 predicts poor prognosis in acute myeloid leukaemia

The mammalian target of rapamycin (mTOR) inhibitor, DNA damage inducible transcript 4 (DDIT4), has inducible expression in response to various cellular stresses. In multiple malignancies, studies have shown that DDIT4 participates in tumorigenesis and impacts patient survival. We aimed to study the prognostic value of DDIT4 in acute myeloid leukaemia (AML), which is currently unclear. Firstly, The Cancer Genome Atlas was screened for AML patients with complete clinical characteristics and DDIT4 expression data. A total of 155 patients were included and stratified according to the treatment modality and the median DDIT4 expression levels. High DDIT4 expressers had shorter overall survival (OS) and event‐free survival (EFS) than the low expressers among the chemotherapy‐only group (all P < .001); EFS and OS were similar in the high and low DDIT4 expressers of the allogeneic haematopoietic stem cell transplantation (allo‐HSCT) group. Furthermore, in the DDIT4^high group, patients treated with allo‐HSCT had longer EFS and OS than those who received chemotherapy alone (all P < .01). In the DDIT4^low group, OS and EFS were similar in different treatment groups. Secondly, we analysed two other cytogenetically normal AML (CN‐AML) cohorts derived from the Gene Expression Omnibus database, which confirmed that high DDIT4 expression was associated with poorer survival. Gene Ontology (GO) enrichment analysis showed that the genes related to DDIT4 expression were mainly concentrated in the acute and chronic myeloid leukaemia signalling pathways. Collectively, our study indicates that high DDIT4 expression may serve as a poor prognostic factor for AML, but its prognostic effects could be outweighed by allo‐HSCT.

Prognostic role of DOK family adapters in acute myeloid leukemia

Acute myeloid leukemia (AML) is a genetically and clinically heterogeneous disease. Gene mutational and expressional profile can aid the identification of different prognostic subgroups. Downstream of tyrosine kinase (DOK) proteins are a multigenic family of adaptors; some of them are key negative regulators of immune cell signaling. However, the expression and clinical implication of DOK family in AML has rarely been investigated. A total of 155 AML patients with DOK family (DOK1-7) expression data from The Cancer Genome Atlas database were enrolled in the study. In patients who only received chemotherapy, those with high expressions of DOK4 or DOK5 had significantly shorter EFS and OS than patients with low expressions (all P < 0.001), whereas high DOK7 expressers had longer EFS and OS than the low expressers (all P < 0.05). In patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), however, all DOK members had no impact on EFS and OS. Multivariate analysis confirmed that high DOK5 expression was an independent risk factor for EFS and OS in untransplanted patients (all P < 0.05). Our study suggests that in AML, high expressions of DOK4 and DOK5 are adverse prognostic factors, high DOK7 expression is a good prognostic factor, but their effects can be overcome by allo-HSCT.

Prognostic value of the FUT family in acute myeloid leukemia

Genetic abnormalities are more frequently viewed as prognostic markers in acute myeloid leukemia (AML) in recent years. Fucosylation, catalyzed by fucosyltransferases (FUTs), is a post-translational modification that widely exists in cancer cells. However, the expression and clinical implication of the FUT family (FUT1-11) in AML has not been investigated. From the Cancer Genome Atlas database, a total of 155 AML patients with complete clinical characteristics and FUT1-11 expression data were included in our study. In patients who received chemotherapy alone showed that high expression levels of FUT3, FUT6, and FUT7 had adverse effects on event-free survival (EFS) and overall survival (OS) (all P < 0.05), whereas high FUT4 expression had favorable effects on EFS and OS (all P < 0.01). However, in the allogeneic hematopoietic stem cell transplantation (allo-HSCT) group, we only found a significant difference in EFS between the high and low FUT3 expression subgroups (P = 0.047), while other FUT members had no effect on survival. Multivariate analysis confirmed that high FUT4 expression was an independent favorable prognostic factor for both EFS (HR = 0.423, P = 0.001) and OS (HR = 0.398, P < 0.001), whereas high FUT6 expression was an independent risk factor for both EFS (HR = 1.871, P = 0.017) and OS (HR = 1.729, P = 0.028) in patients who received chemotherapy alone. Moreover, we found that patients with low FUT4 and high FUT6 expressions had the shortest EFS and OS (P < 0.05). Our study suggests that high expressions of FUT3/6/7 predict poor prognosis, high FUT4 expression indicates good prognosis in AML; FUT6 and FUT4 have the best prognosticating profile among them, but their effects could be neutralized by allo-HSCT.

High IFITM3 expression predicts adverse prognosis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a malignancy caused by the uncontrolled and dysregulated clonal expansion of abnormal myeloid primordial cells. In general, the prognosis of AML remains poor despite new discoveries in its pathogenesis and treatment. It is crucial to find early and sensitive biomarkers and continue to explore active targeted treatments. Interferon-induced transmembrane protein (IFITM) family is an important part of the interferon signaling pathway and participate in the regulation of immune cell signaling, adhesion, cancer, and liver cell migration. However, the clinical and prognostic value of the IFITM family in AML has rarely been studied. We screened The Cancer Genome Atlas database and found 155 AML patients with IFITM family (IFITM1-5) expression data. In patients who only received chemotherapy, those with high IFITM3 expression had significantly shorter event-free survival (EFS) and overall survival (OS) than patients with low expression (all P < 0.05). Multivariate analysis demonstrated that high IFITM3 expression was an independent risk factor for EFS and OS in patients only received chemotherapy (all P < 0.05). In patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), however, all IFITM members had no impact on either EFS or OS. In conclusion, our study elucidated that high IFITM3 expression could be an adverse prognostic factor for AML, whose effect might be overcome by allo-HSCT.

Enhanced expressions of FHL2 and iASPP predict poor prognosis in acute myeloid leukemia

iASPP is a negative regulator of the apoptotic function of p53, and it can enhance the ability of hematopoietic stem cells to self-renew and resist chemo- and radiation therapy. Recent study showed that iASPP could impact the proliferation and apoptosis of leukemia cells by interacting with FHL2. However, whether they have prognostic significance in acute myeloid leukemia (AML) is unknown. Eighty-four AML patients with FHL2 and iASPP expression data from The Cancer Genome Atlas database were enrolled in the study. Patients with high expressions of FHL2 and iASPP had significantly shorter event-free survival (EFS) and overall survival (OS) than patients with low expressions (P = 0.005, P = 0.003, respectively). Univariate analysis indicated that high expressions of FHL2 or iASPP were unfavorable for EFS and OS (all P < 0.05), while multivariate analysis confirmed that high FHL2 expression was an independent risk factor for EFS and OS (all P < 0.05). In patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), however, EFS and OS were not significantly different between FHL2 or iASPP high- and low-expression groups. Our results suggested that high expressions of FHL2 and iASPP were poor prognostic factors for AML, but the prognostic effect might be overcome by allo-HSCT.

A reevaluation of erythroid predominance in Acute Myeloid Leukemia using the updated WHO 2016 Criteria

The 2016 WHO update changed the diagnostic criteria for myeloid neoplasms with erythroid predominance, limiting the diagnosis of acute myeloid leukemia to cases with ≥20% blasts in the bone marrow or peripheral blood. Although acute myeloid leukemia with ≥50% erythroid cells has historically been presumed to represent acute myeloid leukemia with myelodysplasia-related changes, this hypothesis has never been systematically examined. We sought to investigate the clinicopathologic, cytogenetic, and molecular features of acute myeloid leukemia with erythroid predominance to subclassify cases as defined by the 2016 WHO. We retrospectively identified patients with ≥50% erythroid precursors and either ≥20% bone marrow blasts or ≥20% peripheral blood blasts at the time of initial diagnosis at seven major academic centers. Laboratory and clinical data were obtained. Patients were then reclassified according to 2016 WHO guidelines. A matched control group was also obtained. We identified 146 patients with acute myeloid leukemia with erythroid predominance (62% M, average age: 62 y, range: 5-93 y). Of these, 91 were acute myeloid leukemia with myelodysplasia-related changes, 20 (14%) were therapy-related myeloid neoplasm, 23 (16%) acute myeloid leukemia, not otherwise specified, and ten acute myeloid leukemia with recurrent cytogenetic/molecular abnormalities. The bone marrow blast count ranged from 9-41%. There was no difference in survival for patients with erythroid predominance compared to patients with acute myeloid leukemia without erythroid proliferations. In a multivariable analysis, cytogenetic risk was the only significant predictor of survival. We find a significantly lower rate of FLT3 and RAS pathway alterations in acute myeloid leukemia with erythroid predominance compared to controls. Our study is one of the first to apply the 2016 WHO guidelines for classification of acute myeloid leukemia. We find acute myeloid leukemia with erythroid predominance is a heterogeneous group and that erythroid richness has no impact on overall survival.

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.

Changes in the World Health Organization 2016 classification of myeloid neoplasms everyone should know

PURPOSE OF REVIEW

This review highlights the main changes in the revised 2016 WHO classification of myeloid neoplasms (published in 2017) that impact diagnosis and ultimately impact management of patients with these diseases.

RECENT FINDINGS

The revision was based on data accumulated since the 2008 WHO classification, much of which relate to new molecular genetic information about these neoplasms. This massive recent influx of data concerning the significance of pathogenic mutations has affected all myeloid neoplasm categories. The new information has been incorporated as part of the diagnostic criteria of many diseases and has led to the creation of new provisional entities defined by genetic features. Germline mutations that predispose to myeloid neoplasms are also emerging as important findings that impact disease classification.

SUMMARY

The growing body of genetic data have not only altered the classification of myeloid neoplasms, but are also impacting patient management. Genetically-defined disease categories have characteristic prognoses and predicted clinical behavior. Some mutations are associated with responsiveness to certain therapies, including those that target relevant oncogenes. The disease categories in the new classification facilitate the application of risk-adapted therapy based on the most recently available data.

Erythroleukemia-historical perspectives and recent advances in diagnosis and management

Acute erythroleukemia is a rare form of acute myeloid leukemia recognized by its distinct phenotypic attribute of erythroblastic proliferation. After a century of its descriptive history, many diagnostic, prognostic, and therapeutic implications relating to this unique leukemia subset remain uncertain. The rarity of the disease and the simultaneous involvement of its associated myeloid compartment have complicated in vitro studies of human erythroleukemia cell lines. Although murine and cell line erythroleukemia models have provided valuable insights into pathophysiology, translation of these concepts into treatment are not forthcoming. Integration of knowledge gained through a careful study of these models with more recent data emerging from molecular characterization will help elucidate key mechanistic pathways and provide a much needed framework that accounts for erythroid lineage-specific attributes. In this article, we discuss the evolving diagnostic concept of erythroleukemia, translational aspects of its pathophysiology, and promising therapeutic targets through an appraisal of the current literature.

An analysis of 97 previously diagnosed de novo adult acute erythroid leukemia patients following the 2016 revision to World Health Organization classification

Background

The incidence of acute erythroid leukemia subtype (AEL) is rare, accounting for 5% of cases of acute myeloid leukemia (AML), and the outcome is dismal. However, in 2016 revision to the WHO classification, the subcategory of AEL has been removed. Myeloblasts are redefined as the percentage of total marrow cells, not non-erythroid cells. Therefore, the previously diagnosed AEL cases are currently diagnosed as AML or myelodyspalstic syndrome (MDS) according to new criteria.

Methods

We respectively reviewed cases of 97 de novo previously diagnosed AEL and all the patients were diagnosed as AML or MDS according to the new classification scheme, and then the clinical characteristics of these two subtypes were compared. Statistical analyses were performed by SPSS software version 18.0.

Results

The median age was 37 years-old, the two-thirds of previous AEL cases were diagnosed as MDS, and there was no obvious difference between two subtypes except for male/female ratio and age. Cytogenetic, rather than MDS/AML subtypes, can better represent the prognostic factor of previously diagnosed AEL patients. When the cytogenetic risk of patients belonged to MRC intermediate category and age were below 40 years-old in previous AEL cases, the patients who received induction chemotherapy without transplantation had a similar survival compared with the patients who underwent transplantation (3-year OS: 67.2% vs 68.5%).

Conclusions

Cytogenetic, rather than MDS/AML subtypes, can better represent the prognostic factor of previously diagnosed AEL patients. Transplantation was a better choice for those whose cytogenetic category was unfavorable.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3528-6) contains supplementary material, which is available to authorized users.

Pure erythroid leukemia

The category of acute erythroid leukemia was significantly revised in the recently published 2016 revision to the World Health Organization (WHO) classification of myeloid neoplasms. In the previous 2008 WHO classification, acute erythroid leukemia was categorized into two subtypes: erythroleukemia and pure erythroid leukemia (PEL), whereas in the 2016 WHO update, erythroleukemia was merged into myelodysplastic syndrome, and PEL becomes the only type of acute erythroid leukemia. PEL is a rare and aggressive form of acute leukemia whose biology remains poorly characterized. In this review, we discuss the clinicopathologic features, diagnosis, putative pathogenesis, and molecular biology of PEL, with an overview of novel concepts and future directions in this area.

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.

Erythroleukemia shares biological features and outcome with myelodysplastic syndromes with excess blasts: a rationale for its inclusion into future classifications of myelodysplastic syndromes

Erythroleukemia was considered an acute myeloid leukemia in the 2008 World Health Organization (WHO) classification and is defined by the presence of ≥50% bone marrow erythroblasts, having <20% bone marrow blasts from total nucleated cells but ≥20% bone marrow myeloblasts from nonerythroid cells. Erythroleukemia shares clinicopathologic features with myelodysplastic syndromes, especially with erythroid-predominant myelodysplastic syndromes (≥50% bone marrow erythroblasts). The upcoming WHO revision proposes to eliminate the nonerythroid blast cell count rule and to move erythroleukemia patients into the appropriate myelodysplastic syndrome category on the basis of the absolute blast cell count. We conducted a retrospective study of patients with de novo erythroleukemia and compared their clinico-biological features and outcome with those of de novo myelodysplastic syndromes, focusing on erythroid-predominant myelodysplastic syndromes. Median overall survival of 405 erythroid-predominant myelodysplastic syndromes without excess blasts was significantly longer than that observed in 57 erythroid-predominant refractory anemias with excess blasts-1 and in 59 erythroleukemias, but no significant difference was observed between erythroid-predominant refractory anemias with excess blasts-1 and erythroleukemias. In this subset of patients with ≥50% bone marrow erythroblasts and excess blasts, the presence of a high-risk karyotype defined by the International Prognostic Scoring System or by the Revised International Prognostic Scoring System was the main prognostic factor. In the same way, the survival of 459 refractory anemias with excess blasts-2, independently of having ≥20% bone marrow blasts from nonerythroid cells or not, was almost identical to the observed in 59 erythroleukemias. Interestingly, 11 low-blast count erythroleukemias with 5 to <10% bone marrow blasts from total nucleated cells showed similar survival than the rest of erythroleukemias. Our data suggest that de novo erythroleukemia is in the spectrum of myelodysplastic syndromes with excess blasts and support its inclusion into future classifications of myelodysplastic syndromes.

The effects of azacitidine on the response and prognosis of myelodysplastic syndrome and acute myeloid leukemia involving a bone marrow erythroblast frequency of >50

We reviewed the cases of 68 consecutive patients who were diagnosed with myelodysplastic syndrome (MDS, n=61) or acute erythroleukemia (AEL, n=7) according to the World Health Organization (WHO) 2008 criteria and had previously been treated with azacitidine, a hypomethylating agent. Fifteen MDS patients had bone marrow erythroblast frequencies of ≥50%, and 6 out of the 7 AEL patients were reclassified as MDS (refractory anemia with excess blasts [RAEB]-1: 1, RAEB-2: 5) according to the revised WHO 2016 criteria. There was no difference between the overall response ratio (41%), as determined by a hematological improvement in at least one of 3 lineages, of these erythroid rich patients and that of the control group, which comprised 46 MDS patients with bone marrow erythroblast frequencies of <50%. Three MDS patients that exhibited erythroid predominance achieved complete remission. The overall survival period (median: 15 months) of the erythroblast-predominant group was not inferior to that of the control group (median: 16 months). These results indicate that azacitidine is a promising treatment option for MDS/AEL irrespective of the numbers of erythroid cells in the patient's bone marrow.

Acute erythroid leukemia with <20% bone marrow blasts is clinically and biologically similar to myelodysplastic syndrome with excess blasts

In acute erythroleukemia, erythroid/myeloid subtype, blasts usually comprise 5-19% of total bone marrow cells, similar to the myelodysplastic syndrome subtype refractory anemia with excess blasts; recent studies have raised the question if acute erythroleukemia should be considered as a myelodysplastic syndrome subtype. We reviewed 77 de novo acute erythroleukemia and 279 de novo refractory anemia with excess blasts from three large medical centers. Compared to refractory anemia with excess blasts, acute erythroleukemia patients had higher total bone marrow blasts, lower platelets, hemoglobin, and absolute neutrophil counts, with more patients being assigned a very-poor-karyotype risk and very-high Revised International Prognostic Scoring System score. Induction chemotherapy was administered to 55% of acute erythroleukemia patients, but was not associated with longer overall survival compared to acute erythroleukemia patients treated with lower-intensity therapies or supportive care (P=0.44). In multivariable analysis of all patients, Revised International Prognostic Scoring System very high (P<0.0001) or high (P=0.005) risk, but not a diagnosis of acute erythroleukemia (P=0.30), were independent risk factors for shorter overall survival. Our data show that acute erythroleukemia patients have similar risk-adjusted outcome to refractory anemia with excess blasts patients and do not appear to gain survival advantage with acute myeloid leukemia-type induction chemotherapy. These data suggest that acute erythroleukemia, erythroid/myeloid subtype with <20% blasts may be more appropriately classified as refractory anemia with excess blasts rather than as an acute myeloid leukemia subtype.

Considering Bone Marrow Blasts From Nonerythroid Cellularity Improves the Prognostic Evaluation of Myelodysplastic Syndromes

PURPOSE

WHO classification of myeloid malignancies is based mainly on the percentage of bone marrow (BM) blasts. This is considered from total nucleated cells (TNCs), unless there is erythroid-hyperplasia (erythroblasts ≥ 50%), calculated from nonerythroid cells (NECs). In these instances, when BM blasts are ≥ 20%, the disorder is classified as erythroleukemia, and when BM blasts are < 20%, as myelodysplastic syndrome (MDS). In the latter, the percentage of blasts is considered from TNCs.

PATIENTS AND METHODS

We assessed the percentage of BM blasts from TNCs and NECs in 3,692 patients with MDS from the Grupo Español de Síndromes Mielodisplásicos, 465 patients with erythroid hyperplasia (MDS-E) and 3,227 patients without erythroid hyperplasia. We evaluated the relevance of both quantifications on classification and prognostication.

RESULTS

By enumerating blasts systematically from NECs, 22% of patients with MDS-E and 12% with MDS from the whole series diagnosed within WHO categories with < 5% BM blasts, were reclassified into higher-risk categories and showed a poorer overall survival than did those who remained in initial categories (P = .006 and P = .001, respectively). Following WHO recommendations, refractory anemia with excess blasts (RAEB)-2 diagnosis is not possible in MDS-E, as patients with 10% to < 20% BM blasts from TNCs fulfill erythroleukemia criteria; however, by considering blasts from NECs, 72 patients were recoded as RAEB-2 and showed an inferior overall survival than did patients with RAEB-1 without erythroid hyperplasia. Recalculating the International Prognostic Scoring System by enumerating blasts from NECs in MDS-E and in the overall MDS population reclassified approximately 9% of lower-risk patients into higher-risk categories, which indicated the survival expected for higher-risk patients.

CONCLUSION

Regardless of the presence of erythroid hyperplasia, calculating the percentage of BM blasts from NECs improves prognostic assessment of MDS. This fact should be considered in future WHO classification reviews.

Myelodysplastic syndromes following therapy with hypomethylating agents (HMAs): development of acute erythroleukemia may not influence assessment of treatment response

This study followed 28 patients with myelodysplastic syndromes (MDS) who showed a rise of bone marrow (BM) erythroids to ≥ 50% following three cycles (1-60) of hypomethylating agent (HMA) therapy. If BM blasts were calculated as a percentage of non-erythroids, 12 (42.9%) patients met the diagnostic criteria for acute erythroleukemia, erythroid/myeloid (AEL). However, none of the patients showed clonal cytogenetic evolution or new mutations. When compared to 47 de novo AEL patients, these 12 patients were less anemic and thrombocytopenic, had less complex karyotypes (p = 0.044) and showed a longer survival, either calculated from diagnosis (p < 0.001) or from the time of AEL (p = 0.005). These findings illustrate that ≥ 50% erythroids may appear in BM post-HMA therapy, likely a combination of reduction of BM granulocytes (p < 0.001) and promotion of normal or abnormal erythroid proliferation. Enumeration of blasts as a percentage of non-erythroid cells may lead to a diagnosis of AEL and mis-interpretation as disease progression.

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.

How unique is pure erythroid leukaemia? A retrospective analysis of seven cases and review of the literature

AIMS

Pure erythroid leukaemia (PEL) is a rare subtype of acute myeloid leukaemia (AML) and its clinicopathological features are not well-defined. The aim of this study was to describe the immunophenotypic, cytogenetic and clinical features of PEL and to compare these with cases of AML with ≥ 50% erythroblasts.

METHODS

Cases of PEL according to WHO morphological criteria diagnosed at three institutions from 1997 to 2013 were included. A comparison cohort comprised of AML with ≥ 50% erythroblasts. The clinical, histopathology, immunophenotypic and cytogenetic features of cases were analysed. We also reviewed the existing literature on PEL, and combined our cohort with previously reported cases of PEL in a pooled analysis.

RESULTS

There were seven cases of PEL diagnosed at our institutions. There was a high incidence of either prior chemoradiotherapy exposure or evolution from pre-existing myelodysplastic syndrome (MDS) (71%). The leukaemic blasts frequently expressed glycophorin C (100%), CD117 (83%) and were myeloperoxidase negative (83%). Complex karyotypes were present in 83% of cases. Median overall survival was 2.9 months. Compared with AML with ≥ 50% erythroblasts, cases of PEL demonstrated a higher incidence of adverse-risk cytogenetics (p=0.01) and prior exposure to chemoradiotherapy (p=0.01).

CONCLUSIONS

PEL appears to be a unique entity that is often secondary or therapy related, commonly features a complex karyotype and has a poor prognosis. It is morphologically and immunophenotypically distinct from other cases of AML with erythroid hyperplasia.

Reclassifying myelodysplastic syndromes: what's where in the new WHO and why

A revision to the 4th edition of the WHO Classification of myelodysplastic syndromes (MDSs), originally published in 2008, is expected in mid-2016. Based on recommendations of a Clinical Advisory Committee, the revision will aim to incorporate new discoveries in MDS that impact existing disease categories. Although the basic diagnostic principles of the WHO classification remain unchanged, several changes to the classification are proposed. All revisions are considered preliminary until the actual publication of the monograph and online document. Proposals for change include abandoning the routine use of "refractory anemia/cytopenia" in the various disease names, including the prognostic significance of gene mutations in MDS, revising the diagnostic criteria for MDS entities with ring sideroblasts based on the detection of SF3B1 mutations, modifying the cytogenetic criteria for MDS with isolated del(5q), reclassifying most cases of the erythroid/myeloid type of acute erythroleukemia, and recognizing the familial link in some cases of MDS. This review will provide details of the major proposed changes as well as rationale for the revisions.

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.

Serial assessment of suspected myelodysplastic syndromes: significance of flow cytometric findings validated by cytomorphology, cytogenetics, and molecular genetics

The significance of flow cytometry indicating myelodysplasia without proof of myelodysplasia by cytomorphology remains to be clarified. We evaluated follow-up analyses in 142 patients analyzed in parallel by flow cytometry, cytomorphology and cytogenetics for suspected myelodysplasia without proof of myelodysplasia by cytomorphology. At initial assessment, flow cytometry indicated myelodysplasia in 64 of 142 (45.1%) patients. In 9 of 142 (6.3%) patients, cytogenetics revealed aberrant karyotypes at first evaluation that were found in 5 of 64 (7.8%) patients rated with myelodysplasia by flow cytometry. The remaining 133 patients without proof of myelodysplasia by cytomorphology and with normal karyotype underwent follow-up analyses that confirmed myelodysplasia by cytomorphology, cytogenetics or molecular genetics in 47 (35.3%) after a median interval of nine months (range 1-53 months). As far as initial flow cytometry results are concerned, this applied to 30 of 59 (50.1%) with myelodysplasia, 10 of 42 (23.8%) with "possible myelodysplasia" (minor antigen aberrancies only) and 7 of 32 (21.9%) without myelodysplasia (P=0.004). Notably, in these latter 7 patients, flow cytometry results changed at follow up to "possible myelodysplasia" (n=4) and "myelodysplasia" (n=2). These data argue in favor of including flow cytometry along with cytomorphology, cytogenetics and molecular genetics to diagnose myelodysplasia, and suggest a closer monitoring of patients with myelodysplasia-typical aberrant antigen expression found by flow cytometry.

Acute myeloid leukemia (AML) with erythroid predominance exhibits clinical and molecular characteristics that differ from other types of AML

The clinical importance of erythroid predominance in bone marrow of patients with acute myeloid leukemia (AML) is controversial. These cases represent a heterogeneous group of diseases that historically have been classified into different categories. We studied 313 AML patients and specifically compared the clinical, cytogenetic, and molecular features of cases of AML with erythroid predominance, arbitrarily defined as ≥50% erythroid precursors, to AML cases without erythroid predominance. We also assessed 51 patients with a high-grade myelodysplastic syndrome (MDS), refractory anemia with excess blasts (RAEB). All neoplasms were classified according to the World Health Organization classification. With the exception of therapy-related AML/MDS, the presence of erythroid predominance in variously classified categories of AML was associated with a survival advantage. In addition, AML with erythroid predominance had a lower frequency of cytogenetic abnormalities as well as a lower frequency of mutations involving NPM1, NRAS and FLT3 as compared with AML without erythroid predominance. We conclude that the clinical, cytogenetic, and molecular features of AML with erythroid predominance in the non-therapy-related setting are much closer to those of a high-grade myelodysplastic syndrome than they are to other types of AML.

Erythroid proliferations in myeloid neoplasms

Prominent erythroid proliferations (in which erythroid elements comprise ≥50% of total bone marrow cells) can be seen in various hematopoietic stem cell neoplasms. The myeloproliferative neoplasm polycythemia vera exhibits effective, overexuberant erythropoiesis resulting in an increased red blood cell mass; in contrast, most other diseases characterized by erythroid predominance exhibit ineffective hemopoiesis. The latter include acute erythroid leukemia (erythroid-myeloid and pure erythroid leukemia subtypes) as well as some cases of myelodysplastic syndromes, acute myeloid leukemia with myelodysplasia-related changes, and therapy-related myeloid neoplasms. Some nonneoplastic reactive conditions may also manifest a striking bone marrow erythroid predominance. In this article, we review the literature relevant to this group of diseases for a better understanding of their clinicopathologic features and surrounding controversies. We also examine the position of neoplastic erythroid proliferations in the current 2008 World Health Organization Classification of Myeloid Neoplasms and provide recommendations as to how to approach the differential diagnosis of this group of diseases.