Adult acute megakaryocytic leukemia: an analysis of 37 patients treated at M.D. Anderson Cancer Center

Immunophenotypic markers for the evaluation of minimal/measurable residual disease in acute megakaryoblastic leukemia

Acute megakaryoblastic leukemia is characterized by heterogeneous biology and clinical behavior. Immunophenotypic characteristics include the expression of megakaryocytic differentiation markers (e.g. CD41, CD42a, CD42b, CD61) associated with immaturity markers (CD34, CD117, HLA-DR) and myeloid markers (e.g. CD13, CD33) and even with lymphoid cross-lineage markers (e.g. CD7, CD56). Although the diagnostic immunophenotype has already been well described, given the rarity of the disease, its immunophenotypic heterogeneity and post-therapeutic instability, there is no consensus on the combination of monoclonal markers to detect minimal/measurable residual disease (MRD). Currently, MRD is an important tool for assessing treatment efficacy and prognostic risk. In this study, we evaluated the immunophenotypic profile of MRD in a retrospective cohort of patients diagnosed with acute megakaryoblastic leukemia, to identify which markers, positive or negative, were more stable after treatment and which could be useful for MRD evaluation. The expression profile of each marker was evaluated in sequential MRD samples. In conclusion, the markers evaluated in this study can be combined in an MRD immunophenotypic panel to investigate for megakaryoblastic leukemia. Although this study is retrospective and some data are missing, the information obtained may contribute to prospective studies to validate more specific strategies in the detection of MRD in acute megakaryoblastic leukemia.

Adult acute megakaryoblastic leukemia with persistent diarrhea and extreme thrombocytosis: A very unusual case

ABSTRACT

Acute megakaryoblastic leukemia (AML-M7) is rarely seen in adult patients and patients usually present with cytopenias. Here we discuss diagnostic challenges and pathologic features in a patient with AML-M7 who presented with thrombocytosis and diarrhea. A 63-year-old male patient presented with persistent diarrhea lasting for 2 months, fatigue, and thrombocytosis. The diagnostic workup included a stool analysis, endoscopy colonoscopy, and imaging studies; however, these studies did not reveal any possible etiology. The hematologic evaluation included peripheral blood smear, bone marrow aspiration and biopsy, flow cytometry, and cytogenetic analysis. Eventually, according to pathologic and flow cytometric findings, a diagnosis of AML-M7 was made. Diagnosis of AML-M7 may be challenging, especially in adult patients with atypical presentation. Patients with megakaryoblastic leukemia respond poorly to standard induction regimens and they should be advised to participate in a clinical trial.

Design and preclinical testing of an anti-CD41 CAR T cell for the treatment of acute megakaryoblastic leukaemia

Acute megakaryoblastic leukaemia (AMkL) is a rare subtype of acute myeloid leukaemia (AML) representing 5% of all reported cases, and frequently diagnosed in children with Down syndrome. Patients diagnosed with AMkL have low overall survival and have poor outcome to treatment, thus novel therapies such as CAR T cell therapy could represent an alternative in treating AMkL. We investigated the effect of a new CAR T cell which targets CD41, a specific surface antigen for M7-AMkL, against an in vitro model for AMkL, DAMI Luc2 cell line. The performed flow cytometry evaluation highlighted a percentage of 93.8% CAR T cells eGFP-positive and a limited acute effect on lowering the target cell population. However, the interaction between effector and target (E:T) cells, at a low ratio, lowered the cell membrane integrity, and reduced the M7-AMkL cell population after 24 h of co-culture, while the cytotoxic effect was not significant in groups with higher E:T ratio. Our findings suggest that the anti-CD41 CAR T cells are efficient for a limited time spawn and the cytotoxic effect is visible in all experimental groups with low E:T ratio.

Myeloblasts transition to megakaryoblastic immunophenotypes over time in some patients with myelodysplastic syndromes

OBJECTIVES

In myelodysplastic syndromes (MDS), neoplastic myeloblast (CD34+CD13+CD33+ cells) numbers often increase over time, leading to secondary acute myeloid leukemia (AML). In recent studies, blasts in some MDS patients have been found to express a megakaryocyte-lineage molecule, CD41, and such patients show extremely poor prognosis. This is the first study to evaluate whether myeloblasts transition to CD41+ blasts over time and to investigate the detailed immunophenotypic features of CD41+ blasts in MDS.

METHODS

We performed a retrospective cohort study, in which time-dependent changes in blast immunophenotypes were analyzed using multidimensional flow cytometry (MDF) in 74 patients with MDS and AML (which progressed from MDS).

RESULTS

CD41+ blasts (at least 20% of CD34+ blasts expressing CD41) were detected in 12 patients. In five of these 12 patients, blasts were CD41+ from the first MDF analysis. In the other seven patients, myeloblasts (CD34+CD33+CD41- cells) transitioned to megakaryoblasts (CD34+CD41+ cells) over time, which was often accompanied by disease progression (including leukemic transformation). These CD41+ patients were more frequently observed among patients with monosomal and complex karyotypes. CD41+ blasts were negative for the erythroid antigen, CD235a, and positive for CD33 in all cases, but CD33 expression levels were lower in three cases when compared with CD34+CD41- blasts. Among the five CD41+ patients who underwent extensive immunophenotyping, CD41+ blasts all expressed CD61, but two cases had reduced CD42b expression, three had reduced/absent CD13 expression, and three also expressed CD7.

CONCLUSIONS

Myeloblasts become megakaryoblastic over time in some MDS patients, and examining the megakaryocyte lineage (not only as a diagnostic work-up but also as follow-up) is needed to detect CD41+ MDS. The immunophenotypic features revealed in this study may have diagnostic relevance for CD41+ MDS patients.

Erythroid/megakaryocytic differentiation confers BCL-XL dependency and venetoclax resistance in acute myeloid leukemia

Myeloid neoplasms with erythroid or megakaryocytic differentiation include pure erythroid leukemia, myelodysplastic syndrome with erythroid features, and acute megakaryoblastic leukemia (FAB M7) and are characterized by poor prognosis and limited treatment options. Here, we investigate the drug sensitivity landscape of these rare malignancies. We show that acute myeloid leukemia (AML) cells with erythroid or megakaryocytic differentiation depend on the antiapoptotic protein B-cell lymphoma (BCL)-XL, rather than BCL-2, using combined ex vivo drug sensitivity testing, genetic perturbation, and transcriptomic profiling. High-throughput screening of >500 compounds identified the BCL-XL-selective inhibitor A-1331852 and navitoclax as highly effective against erythroid/megakaryoblastic leukemia cell lines. In contrast, these AML subtypes were resistant to the BCL-2 inhibitor venetoclax, which is used clinically in the treatment of AML. Consistently, genome-scale CRISPR-Cas9 and RNAi screening data demonstrated the striking essentiality of BCL-XL-encoding BCL2L1 but not BCL2 or MCL1, for the survival of erythroid/megakaryoblastic leukemia cell lines. Single-cell and bulk transcriptomics of patient samples with erythroid and megakaryoblastic leukemias identified high BCL2L1 expression compared with other subtypes of AML and other hematological malignancies, where BCL2 and MCL1 were more prominent. BCL-XL inhibition effectively killed blasts in samples from patients with AML with erythroid or megakaryocytic differentiation ex vivo and reduced tumor burden in a mouse erythroleukemia xenograft model. Combining the BCL-XL inhibitor with the JAK inhibitor ruxolitinib showed synergistic and durable responses in cell lines. Our results suggest targeting BCL-XL as a potential therapy option in erythroid/megakaryoblastic leukemias and highlight an AML subgroup with potentially reduced sensitivity to venetoclax-based treatments.

Clinical, immunophenotypic, and cytogenetic characteristics of high-grade myelodysplastic syndromes with CD41-positive progenitor cells

BACKGROUND

Patients with myelodysplastic syndromes (MDS) with progenitors expressing CD41 (CD41+ MDS) showed a poor prognosis in a previous study but their detailed characteristics remain unclear.

METHODS

One hundred thirty-seven subjects at our institution were diagnosed with excess blasts (EB)-1, EB-2, and acute myeloid leukemia with a low blast count (20%-30%). The immunophenotypes of progenitor cells in their bone marrow (BM) were determined by CD45-gating flow cytometry. A false-positive reaction to CD41 was eliminated by examining the flow cytometry data of lymphocytes and monocytes in addition to progenitors and by examining CD42b in histological sections. The characteristics were compared between CD41+ and CD41- MDS patients.

RESULTS

Forty-three patients (31%) were CD41+. Additionally, 91% of the CD41+ MDS patients were very high-risk defined by the Revised International Prognostic Score System, which was higher than in patients with CD41- MDS (p = 0.015). Approximately 60% of the CD41+ MDS patients had a monosomal karyotype and very poor cytogenetics, which was higher than in CD41- MDS patients (p < 0.001). Normal cytogenetics was less common in CD41+ patients (p = 0.0016). Blasts with bleb formation were more abundant in CD41+ MDS patients (p = 0.026). All CD41+ MDS patients were positive for CD13 and were mostly positive for CD33. The frequency of aberrant expression of other antigens on progenitors was similar between CD41+ and CD41- MDS patients.

CONCLUSIONS

We determined clinical, immunophenotypic, and cytogenetic characteristics of CD41+ MDS patients. Further studies are needed to improve the survival of these patients.

c-Mpl-del, a c-Mpl alternative splicing isoform, promotes AMKL progression and chemoresistance

Acute megakaryocytic leukemia (AMKL) is a clinically heterogeneous subtype of acute myeloid leukemia characterized by unrestricted megakaryoblast proliferation and poor prognosis. Thrombopoietin receptor c-Mpl is a primary regulator of megakaryopoeisis and a potent mitogenic receptor. Aberrant c-Mpl signaling has been implicated in a myriad of myeloid proliferative disorders, some of which can lead to AMKL, however, the role of c-Mpl in AMKL progression remains largely unexplored. Here, we identified increased expression of a c-Mpl alternative splicing isoform, c-Mpl-del, in AMKL patients. We found that c-Mpl-del expression was associated with enhanced AMKL cell proliferation and chemoresistance, and decreased survival in xenografted mice, while c-Mpl-del knockdown attenuated proliferation and restored apoptosis. Interestingly, we observed that c-Mpl-del exhibits preferential utilization of phosphorylated c-Mpl-del C-terminus Y607 and biased activation of PI3K/AKT pathway, which culminated in upregulation of GATA1 and downregulation of DDIT3-related apoptotic responses conducive to AMKL chemoresistance and proliferation. Thus, this study elucidates the critical roles of c-Mpl alternative splicing in AMKL progression and drug resistance, which may have important diagnostic and therapeutic implications for leukemia accelerated by c-Mpl-del overexpression.

Significance of bone marrow fibrosis in acute myeloid leukemia for survival in the real-world

Acute myeloid leukemia (AML) is a highly heterogeneous hematologic malignancy characterized by the proliferation of myeloid blasts. Bone marrow fibrosis (BMF), characterized by increased deposition of reticulin or collagen fibers, can occur in AML. International authoritative guidelines do not mention AML patients with BMF and the reported studies are inconsistent. Therefore, we retrospectively analyzed the clinical data of newly diagnosed AML patients in our hospital and compared the clinical characteristics, gene mutations and prognosis of AML patients with or without BMF. We found AML patients with BMF tended to be older, were more prone to hepatosplenomegaly, their level of β2-MG was higher and they often had karyotypes associated with a poor prognosis. The proportion of AML patients without BMF was high in the intermediate-risk group and low in the high-risk group. The mutation rates of ASXL1 and TET2 genes were higher and that of CEBPA was lower in the BMF group. Multivariate analysis showed BMF had independent prognostic significance. AML patients without BMF had higher CR/CRi rate, and the time of hematopoietic recovery in patients achieving CR/CRi was longer in BMF group. The degree of BMF, prognostic level and blasts in peripheral blood were independent risk factors for CR/CRi in newly diagnosed AML. AML patients in the BMF group, especially those with BMF ≥ 2, had a lower OS rate. In age<60 years old group, the higher the degree of BMF was, the shorter the median survival time and the lower the OS rate. In age ≥ 60 years old group, the median survival time in the BMF-1 and the BMF-2/3 groups was shorter. For AML with low, intermediate and high risk, there was always a lower OS rate in patients with BMF. The median survival of AML patients decreased with an increasing degree of BMF in different risk stratifications. BMF had no effect on OS of AML patients with HSCT. In conclusion, AML patients with BMF have a poor prognosis, and BMF was an independent prognostic factor for OS. The assessment of BMF was of great significance for the treatment efficacy and prognosis of newly diagnosed AML.

Diagnostic challenge in mixed phenotype acute leukemia with T/megakaryocyte or T/myeloid lineages accompanied by t(3;3)

Background

The diagnosis of mixed phenotype acute leukemia (MPAL) with T/megakaryocyte or T/myeloid lineages accompanied by t(3;3) is always a challenge. Therefore, multiple experimental methods are usually required to avoid misdiagnosis. In this report, we presented a rare case of MPAL with T/myeloid lineages accompanied by t(3;3) and discussed the experience of differential diagnosis and our appreciation of the MPAL with T/megakaryocyte and T/myeloid lineages accompanied by t(3;3).

Case presentation:

A 31-year-old woman was admitted to our hospital due to recurrent fever for 20 days. Two distinct blast populations were detected by flow cytometry analysis: one population fulfills the immunophenotypic criteria for T-lymphoblastic leukemia, while the other population is highly suggestive of megakaryoblasts. These immunophenotypic features support the diagnosis of MPAL (T/megakaryocyte), which is rarely reported​. Interestingly, a complex karyotype was detected afterward by cytogenetics with t(3;3)(q21;q26.2), indicating a diagnosis of AML with t(3;3), a subset of which is also characterized by megakaryocytic markers such as CD41 and CD61. It seems that the second blast population detected by flow cytometry could not be classified into either diagnosis based on the morphology, immunophenotyping, and even cytogenetic findings, posing a real diagnostic problem because of the lack of clear-cut cytogenetic morphological defined criteria to distinguish between acute megakaryocytic leukemia and AML with t(3;3). Combining all of the examination data, this case was ultimately diagnosed as MPAL (T + My)-NOS with t(3;3) through differential diagnosis. Before the cytogenetic results were available, the patient received an acute lymphoblastic leukemia (ALL) regimen for MPAL treatment, but the effect was unsatisfactory. After the diagnosis was clear, she received an AML-like regimen with azacitidine for 7 days and venetoclax for 14 days, and achieved complete morphological remission.

Conclusion

MPAL with either T/megakaryocyte or T/myeloid lineages accompanied by t(3;3) is rare, and it is difficult to make a clear diagnosis. Thus, comprehensive examinations, including bone marrow cell morphology, flow cytometry analysis, cytogenetics, and molecular analysis are recommended to avoid misdiagnosis. AML-like regimen including azacitidine and venetoclax may be effective for treating MPAL (T + My)-NOS with t(3;3).

Pediatric non–Down’s syndrome acute megakaryoblastic leukemia patients in China: A single center's real-world analysis

Non-Down’s syndrome acute megakaryocytic leukemia (non-DS-AMKL) is a subtype of childhood acute myeloid leukemia (AML), whose prognosis, prognostic factors and treatment recommendations have not yet to be defined in children. We conducted a retrospective study with 65 newly diagnosed non-DS-AMKL children from August 2003 to June 2020 to investigate the clinical impact of factors and clinical outcome. Among all 65 patients, 47 of them were treated at our center who received three different regimens due to time point of admission (CAMS-another, CAMS-2009 and CAMS-2016 protocol), and the efficacy were compared. Patients with newly diagnosed non-DS-AMKL accounted for 7.4% of pediatric AML cases. The median age of the patients was 18 months at diagnosis, and over 90% of them were under three-years-old. The overall survival (OS) rates were 33.3% ± 1.7%, 66.7% ± 24.4% and 74.2% ± 4.0% for three groups (CAMS-another, CAMS-2009 and CAMS-2016 regimen), respectively. In CAMS-2016 group, the complete remission (CR) rate after induction was 67.7% (21/31), while the total CR rate after all phases of chemotherapy was 80.6% (25/31). The 2-year survival probability did not significantly improve in patients underwent HSCT when compared with non-HSCT group (75.0% ± 4.7% vs. 73.9% ± 4.6%, p=0.680). Those who had a “dry tap” during BM aspiration at admission had significantly worse OS than those without “dry tap” (33.3% ± 8.6% vs. 84.0% ± 3.6%, p=0.006). Moreover, the results also revealed that patients with CD34+ had significantly lower OS (50.0% ± 6.7% vs. 89.5% ± 3.5%, p=0.021), whereas patients with CD36+ had significantly higher OS than those who were negative (85.0% ± 4.0% vs. 54.5% ± 6.6%, p=0.048). In conclusion, intensive chemotherapy resulted in improved prognosis of non-DS-AMKL children and subclassification may base on “dry tap” and immunophenotypic. Although some progress has been made, outcomes of non-DS-AMKL children remain unsatisfactory, especially in HSCT group, when compared with other AML types.

Immunophenotypic Analysis of Acute Megakaryoblastic Leukemia: A EuroFlow Study

Simple Summary

Acute megakaryoblastic leukemia (AMKL) is a rare and heterogeneous subtype of acute myeloid leukemia (AML). We show that such patients can be identified by flowcytometric immunophenotyping using the standardized EuroFlow panel. AMKL patients show a unique immunophenotypic profile, and among AMKL patients, various subgroups can be distinguished.

Abstract

Acute megakaryoblastic leukemia (AMKL) is a rare and heterogeneous subtype of acute myeloid leukemia (AML). We evaluated the immunophenotypic profile of 72 AMKL and 114 non-AMKL AML patients using the EuroFlow AML panel. Univariate and multivariate/multidimensional analyses were performed to identify most relevant markers contributing to the diagnosis of AMKL. AMKL patients were subdivided into transient abnormal myelopoiesis (TAM), myeloid leukemia associated with Down syndrome (ML-DS), AML—not otherwise specified with megakaryocytic differentiation (NOS-AMKL), and AMKL—other patients (AML patients with other WHO classification but with flowcytometric features of megakaryocytic differentiation). Flowcytometric analysis showed good discrimination between AMKL and non-AMKL patients based on differential expression of, in particular, CD42a.CD61, CD41, CD42b, HLADR, CD15 and CD13. Combining CD42a.CD61 (positive) and CD13 (negative) resulted in a sensitivity of 71% and a specificity of 99%. Within AMKL patients, TAM and ML-DS patients showed higher frequencies of immature CD34+/CD117+ leukemic cells as compared to NOS-AMKL and AMKL-Other patients. In addition, ML-DS patients showed a significantly higher expression of CD33, CD11b, CD38 and CD7 as compared to the other three subgroups, allowing for good distinction of these patients. Overall, our data show that the EuroFlow AML panel allows for straightforward diagnosis of AMKL and that ML-DS is associated with a unique immunophenotypic profile.

Clinicopathological analysis of myeloid sarcoma with megakaryocytic differentiation

Myeloid sarcoma (MS) is defined as a tumour mass consisting of myeloid blasts that occurs at an anatomical site other than bone marrow. MS with megakaryocytic differentiation (MSmgk) is extremely rare and its clinicopathological features have not been well described. We reviewed 11 cases in 11 patients of extramedullary mass-forming malignant tumours composed of immature non-lymphoid haematopoietic cells expressing CD41 with or without concurrent bone marrow lesions. The patients consisted of seven men and four women (1.75:1 male-to-female ratio). The mean and median ages at diagnosis were 50 and 62 years, respectively, ranging from 2 to 78 years. Extramedullary mass lesions were solitary in three cases (27%) and multiple in eight cases (73%). Tumour locations were lymph nodes (6 cases), subcutaneous tissue (3 cases), intramuscular (1 case), and bone (1 case). Seven of the 11 patients (64%) had a history of myelodysplastic syndrome (MDS) or myeloproliferative neoplasm (MPN). Three patients (27%) developed MS during remissions of acute myelogenous leukaemia, and one patient had a recurrence of MS at other sites. Follow-up data were available for four cases. Tumour cells were positive for CD41, CD33, CD34, MPO, and CD68 in 11 (100%), three (27%), seven (64%), four (36%), and seven (64%) cases, respectively. Cytogenetic analysis was successfully performed in two cases. Complex but inconsistent abnormalities were evident. When compared with cases of MS without megakaryocytic differentiation, the survival of MSmgk was significantly shorter (p=0.0033). Compared to MS without megakaryocytic differentiation, MSmgk is more likely to follow MDS/MPN, to involve multiple sites, and to be associated with poorer outcomes. More detailed studies, including genomic or gene expression analyses, could confirm the characteristics of MSmgk.

Salvage Cord Blood Transplantation for Sustained Remission of Acute Megakaryoblastic Leukemia That Relapsed Early after Myeloablative Transplantation

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia accompanied by an aggressive clinical course and dismal prognosis. We herein report a case of AMKL preceded by mediastinal germ cell tumor that relapsed early after allogeneic hematopoietic stem cell transplantation with myeloablative conditioning but was successfully treated using salvage cord blood transplantation (CBT) with reduced-intensity conditioning. Although several serious complications developed, sustained remission with a favorable general condition was ultimately achieved. Although an optimal therapeutic strategy remains to be established, the graft-versus-leukemia effect of CBT may be promising, even for the treatment of refractory AMKL.

Pathological and immunohistochemical aspects of acute megakaryoblastic leukaemia in a cat - Short communication

An adult, mixed-breed, feline leukaemia virus (FeLV-) positive female cat was presented with mucosal jaundice and a history of anorexia and constipation for three days. Physical examination revealed splenomegaly, cachexia, and dehydration. Humane euthanasia was conducted, followed by postmortem examination. Grossly, the cat was icteric, and presented hepatomegaly with multifocal white spots and splenomegaly. Histologically, the bone marrow was nearly completely replaced by a proliferation of megakaryocytes and megakaryoblasts, and there was a proliferation of fibrous connective tissue. Similar neoplastic proliferation was observed infiltrating the liver, lymph nodes, spleen, kidney, skeletal muscle, and lungs. Immunohistochemistry was performed for von Willebrand Factor (VWF), CD79α, CD3, feline immunodeficiency virus, FeLV, and CD61. Marked cytoplasmic labelling was observed in the neoplastic cells for FeLV, VWF and CD61, corroborating the diagnosis of acute megakaryoblastic leukaemia.

Coexistence of myelodysplastic syndrome and acute megakaryoblastic leukemia: An aggressive disease

Coexistent myelodysplastic syndrome and acute megakaryoblastic leukemia is an aggressive disease which often do not respond to standard chemotherapy due to the various molecular and cytogenetic abnormalities. Understanding of the molecular pathogenesis may lead to better therapeutic modalities as current conventional therapies are largely ineffective.

Combined exposure to formaldehyde and PM2.5: Hematopoietic toxicity and molecular mechanism in mice

PM2.5 and formaldehyde (FA) are major outdoor and indoor air pollutants in China, respectively, and both are known to be harmful to human health and to be carcinogenic. Of all the known chronic health effects, leukaemia is one of the most serious health risks associated with these two pollutants. To explore the influence and underlying mechanisms of exposure to formaldehyde and PM2.5 on hematopoietic toxicity, we systematically studied the toxicity induced in hematopoietic organs: bone marrow (BM); spleen; and myeloid progenitor cells (MPCs). Male Balb/c mice were exposed to: PM2.5 (20, 160 μg/kg·d) at a dose of 40 μL per mouse or formaldehyde (0.5, 3.0 mg/m3) for 8 h per day for 2 weeks or co-exposed to formaldehyde and PM2.5 (20 μg/kg·d PM2.5 + 0.5 mg/m3 FA, 20 μg/kg·d PM2.5 + 3 mg/m3 FA, 160 μg/kg·d PM2.5 + 0.5 mg/m3 FA, 160 μg/kg·d PM2.5 + 3 mg/m3 FA) for 2 weeks. Similar toxic effects were found in the formaldehyde-only and PM2.5-only groups, including significant decrease of blood cells and MPCs, along with decreased expression of hematopoietic growth factors. In addition, individual exposure of formaldehyde or PM2.5 increased oxidative stress, DNA damage and immune system disorder by destroying the balance of Th1/Th2, and Treg/Th17. DNA repair was markedly inhibited by deregulating the mammalian target of rapamycin (mTOR) pathway. Combined exposure to PM2.5 and formaldehyde led to more severe effects. Administration of Vitamin E (VE) was shown to attenuate these effects. In conclusion, our findings suggested that PM2.5 and formaldehyde may induce hematopoietic toxicity by reducing the expression of hematopoietic growth factors, increasing oxidative stress and DNA damage, activating the 'immune imbalance' pathway and suppressing the DNA-repair related mTOR pathway. The hematopoietic toxicity induced by combined exposure of PM2.5 and formaldehyde might provide further insights into the increased incidence of hematological diseases, including human myeloid leukaemia.

Acute Coronary Syndrome in Acute Myeloid Leukemia with Maturation Accompanying Megakaryocytic Differentiation

An autopsy case (85-year-old Japanese male) of myeloperoxidase- (MPO-) positive acute myeloid leukemia with maturation (M1) accompanying megakaryocytic differentiation is presented. The patient manifested acute coronary syndrome. Even after emergent percutaneous coronary intervention, his performance status remained poor, so no chemotherapy against leukemia was given. The final white blood cell count reached 291,700/μL, and the platelet count was elevated to 510,000/μL. No cytogenetic studies were performed. He died at the 25^th day of hospitalization. Autopsy revealed marked leukemic infiltration to the endocardium and subendocardial myocardium. Subendocardial myonecrosis was surrounded or replaced by the leukemic blasts, and neither granulation tissue reaction nor fibrosis was observed. In the cardiovascular lumen, lard-like blood clots were formed and microscopically consisted of leukemic blasts and platelets (leukemic thrombi). Infiltration of leukemic blasts was seen in the body cavities and systemic organs including the lung. The MPO-positive blasts lacked azurophilic granules and expressed the stem cell markers, CD34 and CD117 (c-kit). No features of myelofibrosis were seen in the 100% cellular marrow. In the endocardium, liver, lymph nodes, and bone marrow, megakaryocytic cells (CD42b/CD61+, MPO-) were distributed, while the small-sized blastic cells in the blood and tissues predominantly expressed MPO. The blasts lacked expression of CD42b/CD61. Megakaryocytic differentiation might be stimulated by certain tissue factors. AML accompanying megakaryocytic differentiation in certain tissues and organs should be distinguished from acute megakaryoblastic leukemia. The mechanisms provoking acute coronary syndrome in acute myeloid leukemia are discussed.

Clinical Characteristics and Prognosis of 27 Patients with Childhood Acute Megakaryoblastic Leukemia

Background

The aim of this study was to investigate the clinical features and prognostic factors of childhood acute megakaryoblastic leukemia (AMKL).

Material/Methods

The data of 27 cases of childhood AMKL admitted from November 2009 to July 2018 were retrospectively analyzed. The survival analysis and prognostic factors were analyzed by Kaplan-Meier method.

Results

The median follow-up time was 26.4 months in 27 cases, and the complete response rate was 92.31% after 2 chemotherapy courses. Eight patients underwent bone marrow transplantation after 3–6 courses. Five patients died after transplantation, 4 of whom died due to recurrence after transplantation. Of the 27 patients, 10 developed recurrence (37.04%), and 8/10 had recurrence within 1 year. The 3-year overall survival rate and disease-free survival rates were (47±12)% and (36±14)%, respectively. Of the 27 AMKL cases, the 3 with Down syndrome (DS-AMKL) all survived after treatment, and the 3-year overall survival rate was 100%. However, of the other 24 AMKL patients without Down syndrome (non-DS-AMKL), 6 died and 6 abandoned treatment, and the 3-year overall survival rate was only 50%. Univariate analysis showed that 3-year overall survival rate was not correlated to gender, age, number of newly diagnosed white blood cells, karyotype, remission after 2 courses of treatment, and transplant after 3 courses of treatment of childhood AMKL cases. Nevertheless, recurrence and remission after 2 courses of treatment were significantly correlated with 3-year overall survival rate.

Conclusions

Children with non-DS-AMKL have a high degree of malignancy and are prone to early recurrence with a poor prognosis, whereas the prognosis of DS-AMKL is relatively good. Recurrence after treatment and remission after 2 courses of treatment are important factors influencing the prognosis of childhood AMKL. Recurrence after transplantation is the leading cause of death in transplantation patients.

The Comparative Sensitivity of Immunohistochemical Markers of Megakaryocytic Differentiation in Acute Megakaryoblastic Leukemia

OBJECTIVES

Immunohistochemistry (IHC) staining of core biopsy sections often plays an essential role in the diagnosis of acute megakaryoblastic leukemia (AMKL). The goal of this study was to define the relative sensitivities of commonly used stains for markers of megakaryocytic differentiation.

METHODS

The sensitivities of IHC stains for CD42b, CD61, and von Willebrand factor (vWF) were compared in 32 cases of pediatric AMKL.

RESULTS

The sensitivities of CD42b, CD61, and vWF were 90.6%, 78.1% and 62.5%, respectively. When CD42b and CD61 were used together, the combined sensitivity increased to 93.6%. There were no cases in which vWF was positive when both CD42b and CD61 were negative.

CONCLUSIONS

CD42b can reliably be used as a solitary first-line marker for blasts of megakaryocytic lineage, whereas CD61 may be reserved for infrequent cases that are CD42b negative. There is no role for the routine use of vWF when CD42b and CD61 are available.

Clinical diagnosis of adult patients with acute megakaryocytic leukemia

Acute megakaryocytic leukemia (AMKL) is a rare subtype of acute myeloid leukemia (AML), which is challenging to diagnose due to frequent myelofibrosis (MF) and a low percentage of blast cells. In the present study, clinical characteristics and experimental observations in 9 adult patients diagnosed with AMKL, who were recruited by the Sino-U.S. Shanghai Leukemia Co-operative Group, were analyzed in order to summarize the diagnostic experience and provide recommendations on diagnosing AMKL. All the patients were diagnosed according to the 2008 World Health Organization diagnostic criteria. The mean age of the patients with AMKL was 59 years (range, 53–68 years). A total of 8 patients had different degrees of anemia, and 2 patients had <5% marrow blasts present in the bone marrow; however, the percentage of positive cells with cluster of differentiation (CD)41 and CD61 expression was >20%, as demonstrated by flow cytometry. A total of 6 patients were positive for platelet-specific antigens, as indicated by immunocytochemistry. Furthermore, 7 patients presented with moderate or marked MF, as demonstrated by a bone marrow biopsy. Karyotypic analysis indicated that 6 patients had abnormal karyotypes. Only 1 patient exhibited the Janus kinase 2V617F mutation. Treatment efficiency was notably poor, with a median survival time of 6.0 months (range, 1.1–24.0 months). In conclusion, the diagnosis of AMKL requires a combination of the results of bone marrow smears and bone marrow biopsy, immunophenotype or immunohistochemistry. We recommend that routine immunophenotypic analysis should include the CD41 and CD61 markers for diagnosing acute leukemia when bone marrow morphology does not indicate the diagnosis.

Acute Megakaryoblastic Leukemia Developing as Donor Cell Leukemia after Umbilical Cord Blood Transplantation

A 64-year-old man with acute myeloid leukemia underwent umbilical cord blood transplantation (UCBT). After 11 months of complete remission (CR) following UCBT, the bone marrow showed 7.5% myeloblasts. CR was obtained after a single course of azacitidine monotherapy, but the myeloblasts gradually increased in the blood. We made a diagnosis of acute megakaryoblastic leukemia derived from donor cell with a fluorescence in situ hybridization (FISH) analysis of the sex chromosomes and an immunophenotypic analysis. Azacitidine was administered again and produced a therapeutic effect of stable disease. This case suggests that azacitidine may be a useful therapy for patients with acute megakaryoblastic leukemia in situations in which intensive chemotherapy and transplantation are not indicated.

Tetrandrine antagonizes acute megakaryoblastic leukaemia growth by forcing autophagy-mediated differentiation

BACKGROUND AND PURPOSE

The poor prognosis of acute megakaryoblastic leukaemia (AMKL) means there is a need to develop novel therapeutic methods to treat this condition. It was recently shown that inducing megakaryoblasts to undergo terminal differentiation is effective as a treatment for AMKL. This encouraged us to identify a compound that induces megakaryocyte differentiation, which could then act as a potent anti-leukaemia agent.

EXPERIMENTAL APPROACH

The effects of tetrandrine on the expression of CD41 and cell morphology were investigated in AMKL cells. We used CRISPR/Cas9 knockout system to knock out ATG7 and verify the role of autophagy in tetrandrine-induced megakaryocyte differentiation. shNotch1 and CA-Akt were transfected into K562 cells to examine the downstream pathways of ROS signalling and the mechanistic basis of the tetrandrine-induced megakaryocyte differentiation. The anti-leukaemia effects of tetrandrine were analysed both in vitro and in vivo.

KEY RESULTS

A low dose of tetrandrine induced cell cycle arrest and megakaryocyte differentiation in AMKL cells via activation of autophagy. Molecularly, we demonstrated that this effect is mediated by activation of Notch1 and Akt and subsequent accumulation of ROS. In contrast, in normal mouse fetal liver cells, although tetrandrine induced autophagy, it did not affect cell proliferation or promote megakaryocyte differentiation, suggesting a specific effect of tetrandrine in malignant megakaryoblasts. Finally, tetrandrine also showed in vivo efficacy in an AMKL xenograft mouse model.

CONCLUSIONS AND IMPLICATIONS

Modulating autophagy-mediated differentiation may be a novel strategy for treating AMKL, and tetrandrine has the potential to be developed as a differentiation-inducing agent for AMKL chemotherapy.

Adult acute megakaryoblastic leukemia: rare association with cytopenias of undetermined significance and p210 and p190 BCR-ABL transcripts

Acute megakaryocytic leukemia (M7-AML) is a rare form of acute myeloid leukemia (AML), which is associated with poor prognosis. The case presented in the current report is a statement for the difficult diagnosis and clinical management of M7-AML in the context of a previous hematologic disorder of undetermined significance and associated genetic abnormalities. Probably, following the complete hematologic remission and further with induction chemotherapy plus tyrosine kinase inhibitor therapy, the clinical management of this case will be followed by a allogeneic bone marrow transplantation, the only proven therapy to improve overall survival.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology

CONTEXT

- A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia.

OBJECTIVE

- To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage.

DESIGN

- The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus.

RESULTS

- Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported.

CONCLUSIONS

- The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

A novel LSD1 inhibitor NCD38 ameliorates MDS-related leukemia with complex karyotype by attenuating leukemia programs via activating super-enhancers

Lysine-specific demethylase 1 (LSD1) regulates gene expression by affecting histone modifications and is a promising target for acute myeloid leukemia (AML) with specific genetic abnormalities. Novel LSD1 inhibitors, NCD25 and NCD38, inhibited growth of MLL-AF9 leukemia as well as erythroleukemia, megakaryoblastic leukemia and myelodysplastic syndromes (MDSs) overt leukemia cells in the concentration range that normal hematopoiesis was spared. NCD25 and NCD38 invoked the myeloid development programs, hindered the MDS and AML oncogenic programs, and commonly upregulated 62 genes in several leukemia cells. NCD38 elevated H3K27ac level on enhancers of these LSD1 signature genes and newly activated ~500 super-enhancers. Upregulated genes with super-enhancer activation in erythroleukemia cells were enriched in leukocyte differentiation. Eleven genes including GFI1 and ERG, but not CEBPA, were identified as the LSD1 signature with super-enhancer activation. Super-enhancers of these genes were activated prior to induction of the transcripts and myeloid differentiation. Depletion of GFI1 attenuated myeloid differentiation by NCD38. Finally, a single administration of NCD38 causes the in vivo eradication of primary MDS-related leukemia cells with a complex karyotype. Together, NCD38 derepresses super-enhancers of hematopoietic regulators that are silenced abnormally by LSD1, attenuates leukemogenic programs and consequently exerts anti-leukemic effect against MDS-related leukemia with adverse outcome.

A Novel LSD1 Inhibitor T-3775440 Disrupts GFI1B-Containing Complex Leading to Transdifferentiation and Impaired Growth of AML Cells

Dysregulation of lysine (K)-specific demethylase 1A (LSD1), also known as KDM1A, has been implicated in the development of various cancers, including leukemia. Here, we describe the antileukemic activity and mechanism of action of T-3775440, a novel irreversible LSD1 inhibitor. Cell growth analysis of leukemia cell lines revealed that acute erythroid leukemia (AEL) and acute megakaryoblastic leukemia cells (AMKL) were highly sensitive to this compound. T-3775440 treatment enforced transdifferentiation of erythroid/megakaryocytic lineages into granulomonocytic-like lineage cells. Mechanistically, T-3775440 disrupted the interaction between LSD1 and growth factor-independent 1B (GFI1B), a transcription factor critical for the differentiation processes of erythroid and megakaryocytic lineage cells. Knockdown of LSD1 and GFI1B recapitulated T-3775440-induced transdifferentiation and cell growth suppression, highlighting the significance of LSD1-GFI1B axis inhibition with regard to the anti-AML effects of T-3775440. Moreover, T-3775440 exhibited significant antitumor efficacy in AEL and AMKL xenograft models. Our findings provide a rationale for evaluating LSD1 inhibitors as potential treatments and indicate a novel mechanism of action against AML, particularly AEL and AMKL. Mol Cancer Ther; 16(2); 273-84. ©2016 AACR.

[Analysis on the laboratory examination characteristics in 22 patients with acute megakaryoblastic leukemia]

OBJECTIVE

To analyze the ultra microstructures and the expression of platelet peroxidase (PPO) of megakaryocytes from bone marrow, their clinical manifestations and laboratory characteristics in patients with acute megakaryoblastic leukemia (AMKL).

METHODS

Karyocytes from bone marrow of 22 AMKL patients were divided into two parts by lymphocyte separation liquid, one part was used to prepare the ordinary transmission electron microscope specimens to observe the morphological structures of megakaryocytes, the other was used to prepare the histochemical specimens of platelet peroxidase to analyze the positive reaction of PPO in AMKL, which were coupled with the patients' data of with bone marrow morphology, cell chemistry, and chromosome karyotype examination.

RESULTS

Megakaryocytes from 17 of 22 patients were in the first stage, less than 20 µm in diameter, the nucleis were round, the cytoplasm contained microtubules, membranous vesicles and minute dense granules, no demarcation membrane system and surface-connected canalicular system, less dense granules and α-granules; Megakaryocytes in 5 cases were mainly in the first stage, while containing second and third stage megakaryocytes; the positive rate of PPO in megakaryocytes of 22 patients was 0-80%. The primitive and naive megakaryocytes were found in bone marrow smears of 22 cases, CD41 staining of the megakaryocytes was detected in the primitive and naive megakaryocytes, and more complex chromosome karyotype anomalies were observed.

CONCLUSION

The majority of megakaryocytes in AMKL patients were the first stage ones, the rest were second and third stage ones, and the positive PPO reaction was significantly different. CD41 staining of the megakaryocytes was specific with complex chromosome karyotypeswere.

Acute Megakaryoblastic Leukemia with Myelodysplasia-related Changes Associated with ATM Gene Deletion

Ataxia telangiectasia mutated (ATM) is a tumor suppressor gene, and its somatic inactivation plays a role in the pathogenesis of lymphoid malignancies. However, the role of ATM in patients with myeloid malignancies is still unknown. We herein report a case of acute megakaryoblastic leukemia (AMKL) with ATM gene deletion. An 84-year-old Japanese woman presenting with a pale face and pancytopenia was admitted to our institution and diagnosed to have AMKL with ATM gene deletion. She was treated with intravenous azacitidine. The azacitidine treatment was effective for approximately 1 year. Somatic inactivation of the ATM gene may therefore be involved in the pathogenesis of AMKL.

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.

Bone marrow injury induced via oxidative stress in mice by inhalation exposure to formaldehyde

OBJECTIVE

Formaldehyde, a ubiquitous environmental pollutant has been classified as a human leukemogen. However, toxicity of formaldehyde in bone marrow, the target site of leukemia induction, is still poorly understood.

METHODOLOGY/PRINCIPAL FINDINGS

To investigate bone marrow toxicity (bone marrow pathology, hematotoxicity) and underlying mechanisms (oxidative stress, inflammation, apoptosis) in formaldehyde-exposed mice. Male Balb/c mice were exposed to formaldehyde (0, 0.5, and 3.0 mg/m(3)) by nose-only inhalation for 8 hours/day, over a two week period designed to simulate a factory work schedule, with an exposure-free "weekend" on days 6 and 7, and were sacrificed on the morning of day 13. Counts of white blood cells, red blood cells and lymphocytes were significantly (p<0.05) decreased at 0.5 mg/m(3) (43%, 7%, and 39%, respectively) and 3.0 mg/m(3) (52%, 27%, and 43%, respectively) formaldehyde exposure, while platelet counts were significantly increased by 109% (0.5 mg/m(3)) and 67% (3.0 mg/m(3)). Biomarkers of oxidative stress (reactive oxygen species, glutathione depletion, cytochrome P450 1A1 and glutathione s-transferase theta 1 expression), inflammation (nuclear factor kappa-B, tomour necrosis factor alpha, interleukin-1 beta), and apoptosis (activity of cysteine-aspartic acid protease 3) in bone marrow tissues were induced at one or both formaldehyde doses mentioned above.

CONCLUSIONS/SIGNIFICANCE

Exposure of mice to formaldehyde by inhalation induced bone marrow toxicity, and that oxidative stress, inflammation and the consequential apoptosis jointly constitute potential mechanisms of such induced toxicity.

Differential diagnosis of myelofibrosis based on WHO 2008 criteria: acute panmyelosis with myelofibrosis, acute megakaryoblastic leukemia with myelofibrosis, primary myelofibrosis and myelodysplastic syndrome with myelofibrosis

INTRODUCTION

The aim of this study was to characterize clinicopathological features of acute panmyelosis with myelofibrosis (APMF), acute megakaryoblastic leukemia with myelofibrosis (AMKL-MF), primary myelofibrosis (PMF) and myelodysplastic syndrome with myelofibrosis (MDS-MF) in order to provide the keys to the differential diagnosis of bone marrow (BM) fibrosis.

METHODS

We compared age, gender, splenomegaly, serum lactate dehydrogenase level, blood cell counts, blast counts in peripheral blood (PB) and BM, megakaryocyte counts, BM cellularity, dysplasia, and the karyotypes of patients with APMF (n = 6), AMKL-MF (n = 7), PMF (n = 44), and MDS-MF (n = 44).

RESULTS

APMF showed hyperplasia of all three lineages, increase in megakaryocyte count with dysplasia and frequent abnormal karyotypes. AMKL-MF was associated with elevated BM blast counts, decreased BM megakaryocyte count with rare megakaryocytic dysplasia and chromosome 21 abnormality. PMF patients displayed splenomegaly, rare blasts in PB/BM, and JAK2 V617F mutation. MDS-MF patients showed pancytopenia, dysplasia in all three lineages and recurrent chromosomal abnormalities involving chromosome 5,7,12, and 17.

CONCLUSIONS

Although differential diagnosis among APMF, AMKL-MF, PMF, and MDS-MF is very challenging due to the overlapping clinical and morphological features, meticulous investigation of the patient with respect to splenomegaly, blood cell count, PB and BM findings, and karyotype will serve as a guide to correct diagnosis.

An Inv(16)(p13.3q24.3)-encoded CBFA2T3-GLIS2 fusion protein defines an aggressive subtype of pediatric acute megakaryoblastic leukemia

To define the mutation spectrum in non-Down syndrome acute megakaryoblastic leukemia (non-DS-AMKL), we performed transcriptome sequencing on diagnostic blasts from 14 pediatric patients and validated our findings in a recurrency/validation cohort consisting of 34 pediatric and 28 adult AMKL samples. Our analysis identified a cryptic chromosome 16 inversion (inv(16)(p13.3q24.3)) in 27% of pediatric cases, which encodes a CBFA2T3-GLIS2 fusion protein. Expression of CBFA2T3-GLIS2 in Drosophila and murine hematopoietic cells induced bone morphogenic protein (BMP) signaling and resulted in a marked increase in the self-renewal capacity of hematopoietic progenitors. These data suggest that expression of CBFA2T3-GLIS2 directly contributes to leukemogenesis.

[Megakaryoblastic acute leukemia: bone and joint manifestations in a 7-month-old child]

Acute megakaryoblastic leukemia accounts for approximately 3-10% of acute myeloid leukemia in children. Its diagnosis may be difficult because of associated myelofibrosis. We report the case of a 7-month-old child who presented hepatomegaly with bicytopenia. She also developed bone and joint pain with recurrent aseptic arthritis. We suggested the diagnosis of megakaryoblastic leukemia early but multiple bone marrow investigations had been processed without positive results because of sampling problems and lack of abnormal cells in the morphological, phenotypic, and cytogenetic examinations. We had a variety of indirect evidence for our assumption: the x-ray showing periosteal new bone, lytic lesions and metaphyseal bands, bone marrow aspirate smears with micromegakaryocytes, and bone marrow biopsy suggesting myelofibrosis. This was very suggestive of leukemia but we could not prove it and we finally found megakaryoblasts on bone marrow aspirate smears after more than 2 months of investigation and initiated a course of corticosteroids.

Normal and malignant megakaryopoiesis

Megakaryopoiesis is the process by which bone marrow progenitor cells develop into mature megakaryocytes (MKs), which in turn produce platelets required for normal haemostasis. Over the past decade, molecular mechanisms that contribute to MK development and differentiation have begun to be elucidated. In this review, we provide an overview of megakaryopoiesis and summarise the latest developments in this field. Specially, we focus on polyploidisation, a unique form of the cell cycle that allows MKs to increase their DNA content, and the genes that regulate this process. In addition, because MKs have an important role in the pathogenesis of acute megakaryocytic leukaemia and a subset of myeloproliferative neoplasms, including essential thrombocythemia and primary myelofibrosis, we discuss the biology and genetics of these disorders. We anticipate that an increased understanding of normal MK differentiation will provide new insights into novel therapeutic approaches that will directly benefit patients.

Cyto-morphological features of extramedullary acute megakaryoblastic leukemia on fine needle aspiration and cerebrospinal fluid cytology: A case report

Extramedullary deposits may be the presenting feature of acute myeloid leukemia. An early and accurate diagnosis on cytology will aid in correct patient management. This is especially true for patients with acute megakaryoblastic leukemia (AML M7), where bone marrow aspiration may yield only a dry tap. While cytomorphological features of myeloid sarcoma of other types are well recognized due to its rarity, there are only two case reports discussing the morphological details of megakaryoblastic differentiation on aspiration cytology. We present the case of a 25-year-old patient with extramedullary involvement of lymph node and cerebrospinal fluid by AML M7, describing in detail, the morphological features on aspiration as well as exfoliative cytology.

Mosaic Trisomy 21 and Trisomy 14 as Acquired Cytogenetic Abnormalities without GATA1 Mutation in A Pediatric Non-Down Syndrome Acute Megakaryoblastic Leukemia

One case of acute megakaryoblastic leukemia (AMKL) with trisomy 21, trisomy 14 and unmutated GATA1 gene in a phenotypically normal girl was reported. The patient experienced transient myelodysplasia before the onset of AMKL. The bone marrow blasts manifested typical morphology of megakaryoblast both by the May-Giemsa staining and under the electronic microscopy. Leukemic cells were positive for CD13, CD33, CD117, CD56, CD38, CD41 and CD61 in flow cytometry analysis. Cytogenetic study showed karyotype of 48, XX, +14, +21 in 40% metaphases. Known mutations of GATA1 gene in Down syndrome or acquired trisomy 21 were not detected in this case.

Pure erythroid leukemia: a reassessment of the entity using the 2008 World Health Organization classification

Pure erythroid leukemia (PEL) is rare, characterized by a neoplastic proliferation of erythroblasts. Given recent incorporation of molecular genetic findings and clinical features in the revised 2008 World Health Organization classification scheme of acute myeloid leukemia, we questioned if PEL still remains as a distinct subtype of acute myeloid leukemia. In this retrospective study, we identified 18 cases of acute leukemia with morphologic and immunophenotypic features of PEL. Following the current World Health Organization classification algorithm, these cases were classified as: 13 acute myeloid leukemia with myelodysplasia-related changes, 3 therapy-related acute myeloid leukemia, and 1 chronic myelogenous leukemia blast crisis, and one unclassifiable due to insufficient clinical information. All 16 cases with cytogenetic data harbored an extremely complex karyotype and the median overall survival of the 18 patients was 3 months (range, 1-7 months). This survival was significantly shorter than that of patients with acute erythroid leukemia, erythroid/myeloid subtype, or acute myeloid leukemia with myelodysplasia-related changes with erythroid predominance (P<0.001). PEL is characterized as a neoplastic erythroid hyperproliferation with maturation arrest. E-cadherin emerged as the most sensitive and specific marker for immature erythroblasts, and was helpful in distinguishing PEL from other erythroid proliferations. Our study showed that the criteria for acute myeloid leukemia in the 2008 World Health Organization system facilitate reclassification of PEL cases into other acute myeloid leukemia categories, mainly of acute myeloid leukemia with myelodysplasia-related changes. These new assigned categories fail to capture the distinct features of PEL, where the phenotype of PEL correlates with a very complex karyotype and an extremely aggressive clinical course.