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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.

Identification of fusion genes in clinical routine is mostly based on cytogenetics and targeted molecular genetics, such as metaphase karyotyping, fluorescence in situ hybridization and reverse-transcriptase polymerase chain reaction. However, sequencing technologies are becoming more important in clinical routine as processing time and costs per sample decrease. To evaluate the performance of fusion gene detection by RNAsequencing compared to standard diagnostic techniques, we analyzed 806 RNA-sequencing samples from patients with acute myeloid leukemia using two state-of-the-art software tools, namely Arriba and FusionCatcher. RNA-sequencing detected 90% of fusion events that were reported by routine with high evidence, while samples in which RNA-sequencing failed to detect fusion genes had overall lower and inhomogeneous sequence coverage. Based on properties of known and unknown fusion events, we developed a workflow with integrated filtering strategies for the identification of robust fusion gene candidates by RNA-sequencing. Thereby, we detected known recurrent fusion events in 26 cases that were not reported by routine and found discrepancies in evidence for known fusion events between routine and RNA-sequencing in three cases. Moreover, we identified 157 fusion genes as novel robust candidates and comparison to entries from ChimerDB or Mitelman Database showed novel recurrence of fusion genes in 14 cases. Finally, we detected the novel recurrent fusion gene NRIP1- MIR99AHG resulting from inv(21)(q11.2;q21.1) in nine patients (1.1%) and LTN1-MX1 resulting from inv(21)(q21.3;q22.3) in two patients (0.25%). We demonstrated that NRIP1-MIR99AHG results in overexpression of the 3' region of MIR99AHG and the disruption of the tricistronic miRNA cluster miR-99a/let-7c/miR-125b-2. Interestingly, upregulation of MIR99AHG and deregulation of the miRNA cluster, residing in the MIR99AHG locus, are known mechanisms of leukemogenesis in acute megakaryoblastic leukemia. Our findings demonstrate that RNA-sequencing has a strong potential to improve the systematic detection of fusion genes in clinical applications and provides a valuable tool for fusion discovery.

Down syndrome (DS) is a congenital chromosomal abnormality caused by the presence of all or part of a third copy of chromosome 21 (+21). DS is frequently complicated by congenital heart or digestive tract diseases at birth. DS patients are prone to infections and have mental retardation, with dementia such as Alzheimer's disease showing in later life. Furthermore, malignancies with specific characteristics are also highly reported in DS patients compared with non-DS patients. Therefore, DS is believed to be a cancer predisposition syndrome due to the chromosomal instability. Acute myeloid leukemia (AML) and especially acute megakaryoblastic leukemia (AMKL) by French-American-British (FAB) classification are the most frequent hematological malignancies in DS patients, occurring at a rate that is 500 times higher than that in non-DS patients. Interestingly, transient abnormal myelopoiesis (TAM) is observed in approximately 10% of DS neonates with GATA1 mutations, and most TAM patients are asymptomatic and show spontaneous regression; however, about 10%–20% of TAM cases are fatal because of complications such as fetal effusion, liver fibrosis, and other complications. Acute lymphoblastic leukemia (ALL) is also associated with DS, occurring at a rate that is 20 times higher than that in non-DS patients. Furthermore, the prognosis of DS-ALL patients is poorer than that of non-DS-ALL patients. A recent genetic analysis revealed that more than half of DS-ALL cases have a mutation in the CRLF2–JAK pathway, indicating that JAK inhibitors might have a limited effect for DS-ALL patients. Notably, solid tumors such as neuroblastoma, Wilms tumor, and brain tumor, which are frequently observed in non-DS children, are rarely reported in DS children. The reason remains unknown, but it may be because of the triplication of the Down syndrome critical region 1 (DSCR1) gene on chromosome 21. In adult patients with DS, the expected age-adjusted incidence rates of solid tumors are low compared with age-matched euploid cohorts for most cancers except for testicular cancer. Although the average life expectancy of patients with DS will increase with advances in healthcare, the detailed health problems including cancer rates in older DS patients remain unknown. Therefore, these issues will be needed to be addressed in future studies.

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia (AML), which is associated with poor prognosis for all patients except children with t(1;22) or Down syndrome. The frequency of complete remission in case of AMKL is comparable to the frequency of complete remission in other variants of AML, and the median survival is much lower. This determines the necessity to update criteria for assessment of the effect of treatment using flow cytometry definition of the level of minimal residual disease (MRD). Nowadays, there are no unified and standardized approaches for the measurement of MRD in case of myeloid leukemia, including AMKL, which prohibits adequate assessment of the therapy effect and in some cases determination of the indications for allogeneic hematopoietic stem cells transplantation. The article identifies diagnostic features and describes approaches for the measurement of the level of MRD in case of AMKL. Aim. The aim is to demonstrate the algorithms for diagnosing and measuring MRD in case of AML-M7 in children. Materials and methods. The article analyzes the clinical and immunological profile of 10 boys and 4 girls with the initial diagnosis of AMKL between the ages of 3 months 12 years old, 13 of them have received treatment in the FSBI N.N. Blokhin National Medical Research Center of Oncology and one in the GBUZ Morozovsky DGKB between 1995 and 2020, The measurement of MRD was carried out in 6 patients. The measurement of MRD was carried out using both morphocytochemical method and multiparameter flow cytometry with megakaryocyte markers (CD61, CD42, CD41) in combination with other myeloid markers (CD13, CD33), CD34, CD117 and aberrant markers (mainly CD7). Results. We showed that adequate measurement of the level of MRD had required detailed immunophenotyping during diagnosis to determine the aberration of megakaryoblasts. CD9 marker (100%), CD33 myeloid marker (69.2%), stem cell antigen CD34 (46.2%), CD13 (38.2%) in addition to megakaryocyte markers (100%) were most often expressed on blast cells in case of AMKL. The CD117 antigen was present on the blasts in 33.3% of cases. The expression of the T-cell-associated CD7 antigen (46.2%) was frequent. The measurement of MRD was carried out during the treatment (usually after an induction course) on the basis of the markers of megakaryocytic cell line (CD61, CD41, CD42a, CD42b), weak CD45 expression, as well as the immunophenotype characteristics during initial diagnosis. The level of MRD ranged from completely negative (0%; 0.006%) to evident (1.05%). Conclusion. The detection of residual tumor megakaryoblasts in case of AML-M7 using flow cytometry is a promising method to evaluate the effect of therapy. The adequate measurement of the level of MRD requires detailed immunophenotyping during the diagnosis to determine the aberration of megakaryoblasts.

Background Acute megakaryoblastic leukemia (AMKL) is a biologically heterogeneous subtype of acute myeloid leukemia that originates from megakaryocytes. Patients with AMKL with non-Down syndrome (DS) had a poorer prognosis. However, clear prognostic indicators and treatment recommendations for this subgroup remain controversial. Patients and Methods Herein, we performed a retrospective study on 40 patients (age ≤ 18 years) with non-Down syndrome AMKL at our institution. We assessed the effect of different prognostic factors, such as their cytogenetic abnormalities, early treatment response, and the role of hematopoietic stem cell transplantation (HSCT) as post-remission treatment on the outcomes. Results The complete remission (CR) rate of the patients was 57.9% and 81.1%, respectively, at the end of induction therapy 1 and 2. The overall survival (OS) and event-free survival rates at 2 years were 41% ± 13% and 41% ± 10%, respectively. An analysis of the cytogenetic features showed that patients with +21 or hyperdiploid (> 50 chromosomes) had significantly better OS than those in other cytogenetic subgroups (Plog-rank = .048 and Plog-rank = .040, respectively). Besides cytogenetics, an excellent early treatment response (CR and minimal residual disease Conclusion AMKL in patients with non-Down syndrome has a poor outcome. With poor OS but CR rates comparable with other acute myeloid leukemia subtypes, allogenic HSCT may be a better option for post-remission therapy than conventional chemotherapy, especially for those having a poor response to induction therapy.

Down syndrome (DS) is the most common chromosomopathy in humans, usually caused by constitutional trisomy 21. It associates with several developmental anomalies, as well as with an increased risk o...

Transient abnormal myelopoiesis (TAM) is a unique hematological syndrome specific for neonates with Down syndrome. Clinical and hematological manifestations of ТАМ are similar manifestations of acute leukemia, but they may resolve spontaneously by few weeks/months after birth. Summation trisomy 21 and GATA1 mutation in blast clone is a required element for development TAM. Presentation of this syndrome occurs in the first days of life; clinical manifestations may be absent (“silent” TAM) or even lead to death of fetus and neonate. The main interest in the study of this issue is the fact that after spontaneous regression there in 20% of cases at the age of 3–4 years developing acute megakaryoblastic leukaemia (AMKL). The basic transformation factors TAM to AMKL are unknown. In this article we represent 6 cases of TAM identified in Dmitry Rogachev National Research Center for Pediatric Hematology, Oncology, and Immunology from 2012 to 2019. Parents of these patients gave their agreement to use personal data in research and publications.

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 25th 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.

Young males have a unique but rare predilection to develop mediastinal nonseminomatous germ cell tumors (NSGCTs) and concomitant acute megakaryoblastic leukemia (AMKL). Common cytogenetic and molecular abnormalities such as isochromosome 12p and somatic Tumor Protein P53(TP53) and Phosphatase And Tensin Homolog (PTEN) mutations have been reported in the presumed mutual neoplastic clones of origin. We report the case of a 17-year-old male who presented with a mediastinal NSGCT with high-grade sarcomatous transformation and a diagnosis of AMKL approximately 4 months later. Next-generation sequencing revealed identical KRAS Proto-Oncogene, GTPase (KRAS) p.Ala146Thr, TP53 p.Leu257Pro, and PTEN p.Leu181Pro missense mutations at similar variant allele frequencies in both the NSGCT and AMKL samples. Cytogenetic and microarray analyses detected shared copy gains in all chromosomes except chromosomes 9, 13, and Y. Multiple additional clonal chromosomal alterations were detected in the AMKL sample when compared with the NSGCT. This case emphasizes the shared clonal origins of these malignancies and identifies KRAS and other copy number alterations as potential molecular drivers in a subset of these combined diseases.

Long noncoding ribonucleic acids (lncRNAs) are ribonucleic acid (RNA) molecules longer than 200 nucleotides without protein-coding capacity. Several studies have shown that lncRNAs play a pivotal role in the initiation, maintenance, and progression of acute myeloid leukemia (AML), which could make them a promising candidate in the diagnosis and treatment of leukemia. Acute Megakaryoblastic leukemia (AMKL) is a rare form of AML with a poor prognosis and low survival. It has been reported that lncRNA MIR100HG is involved several types of malignancies. In the present study, MIR100HG was downregulated in a human acute megakaryoblastic leukemia cell line (M-07e) using Antisense LNA GapmeRs. In order to assess the expression level of MIR100HG, cell viability, apoptosis, and necrosis (late apoptosis), quantitative reverse transcription polymerase chain reaction (qRT-PCR), Methyl-thiazol Tetrazolium assay, AnnexinV, and propidium iodide staining was performed at different time points after the transfection. In addition, the expression level of TGFβ was evaluated by qRT-PCR. Our results revealed that inhibition of MIR100HG might serve as a new method for inhibition of the proliferation of AMKL cells and therefore, could be a promising approach in medicine for targeted therapy in AMKL.

Reactive myelofibrosis (MF) may be associated with infectious, inflammatory, or neoplastic conditions. Extensive myelofibrosis and indolent course are frequent in acute megakaryoblastic leukemia, but these findings are rarely reported in acute promyelocytic leukemia (APL). Patients with neoplastic disorders associated with MF are reported to have an inferior outcome. However, the effect of this association is not apparent in APL patients. This report presents a case of APL in a pediatric patient in association with significant reticulin fibrosis and osteosclerosis. The case highlights that fibrosis in the marrow can make it more challenging to diagnose acute leukemia. The PML-RARA transcripts can be present with subtle clinical or hematological findings, emphasizing the importance of molecular studies in unexplained cytopenias. Furthermore, in the case of APL, as opposed to other myeloid neoplasms, fibrosis does not appear to be associated with a worse prognosis and can resolve after treatment.

Acute megakaryoblastic leukemia (AMKL) is a subtype of acute myeloid leukemia (AML) accounting for 3%–10% of primary AML in childhood. Clinical manifestations of AML patients can include low grade of fever, diarrhea, easy bruising, failure to growth, and life-threatening clinical manifestations. Laboratory tests are very crucial to make a definitive diagnosis and treatment. We report here an uncommon case of AMKL in a 12-month-old boy who presented with general paleness and fatigue. Based on blood film investigation, bone marrow examination report, and immunophenotyping, he was diagnosed as a case of AMKL without Down syndrome.

BackgroundA high ecotropic viral integration site 1 (EVI1) expression (EVI1high) is an independent prognostic factor in adult acute myeloid leukemia (AML). However, little is known of the prognostic value of EVI1high in pediatric AML. This study aimed to examine the biological and prognostic significance of EVI1high in uniformly treated pediatric patients with AML from a large cohort of seven centers in China.MethodsA diagnostic assay was developed to determine the relative EVI1 expression using a single real-time quantitative polymerase chain reaction in 421 newly diagnosed pediatric AML patients younger than 14 years from seven centers in southern China. All patients were treated with a uniform protocol, but only 383 patients were evaluated for their treatment response. The survival data were included in the subsequent analysis (n = 35 for EVI1high, n = 348 for EVI1low).ResultsEVI1high was found in 9.0% of all 421 pediatric patients with de novo AML. EVI1high was predominantly found in acute megakaryoblastic leukemia (FAB M7), MLL rearrangements, and unfavorable cytogenetic aberrance, whereas it was mutually exclusive with t (8; 21), inv (16)/t (16; 16), CEBPA, NPM1, or C-KIT mutations. In the univariate Cox regression analysis, EVI1high had a significantly adverse 5-year event-free survival (EFS) and overall survival (OS) [hazard ratio (HR) = 1.821 and 2.401, p = 0.036 and 0.005, respectively]. In the multivariate Cox regression analysis, EVI1high was an independent prognostic factor for the OS (HR = 2.447, p = 0.015) but not EFS (HR = 1.556, p = 0.174). Furthermore, EVI1high was an independent adverse predictor of the OS and EFS of patients with MLL rearrangements (univariate analysis: HR = 9.921 and 7.253, both p < 0.001; multivariate analysis: HR = 7.186 and 7.315, p = 0.005 and 0.001, respectively). Hematopoietic stem cell transplantation (HSCT) in first complete remission (CR1) provided EVI1high patients with a tendential survival benefit when compared with chemotherapy as a consolidation (5-year EFS: 68.4% vs. 50.8%, p = 0.26; 5-year OS: 65.9% vs. 54.8%, p = 0.45).ConclusionIt could be concluded that EVI1high can be detected in approximately 10% of pediatric AML cases. It is predominantly present in unfavorable cytogenetic subtypes and predicts adverse outcomes. Whether pediatric patients with EVI1high AML can benefit from HSCT in CR1 needs to be researched further.

Infant acute leukemia is a rare but aggressive disease. Although infant acute leukemia is cytologically and histologically similar to acute leukemia seen in older children and adults, it displays unique and characteristic clinical and genetic characteristics. The features, as well as the extremely young age of the patients, present multiple challenges for treatment. This review focuses on the unique pathology of acute leukemia of infancy, including the genetic characteristics that are specific for these diseases.

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia, in which the bone marrow produce increased numbers of immature abnormal megakaryoblasts. AMKL is rare both in children and adults, but is the most frequent subtype of acute myeloid leukemia (AML) in children with Down syndrome. Morphological diagnosis of this disease could be complicated, thus flow cytometry plays a crucial role in the diagnostics of AMKL. The aim of the present study was to investigate the immunophenotypic characteristics of AMKL in children. The study was approved by the Independent Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology, and Immunology. The study group included 103 patients with AMKL. Antigen expression profile was assessed by multicolor flow cytometry. We identified three groups of patients according to different levels of CD45 expression, and in majority of patients (74%) high level of CD45 expression was detected. Significant immunophenotypic differences between these groups were found. In 56% of patients trisomy of 21 chromosome was detected. Among these patients, 86% belonged to group of high CD45 expression. Moreover, children with trisomy 21 represented the majority in the group with high level of CD45 expression (64%). Also, there were found several significant differences between patients with and without trisomy 21 within the group of high CD45 expression. This study demonstrated the wide immunophenotypic heterogeneity of AMKL. In general, the revealed diversity obviously reflects the biological heterogeneity of this AML subtype.

Improvement in survival has been achieved for children and adolescents with AML but is largely attributed to enhanced supportive care as opposed to the development of better treatment regimens. High risk subtypes continue to have poor outcomes with event free survival rates, Pediatric AML is traditionally treated with chemotherapy and stem cell transplant but some subsets of patients have a poor response to therapy. Here, the authors perform a high throughput screen and identify several FDA approved drugs that might be useful in treating this disease.

Acute megakaryoblastic leukemia (AMegL) is a rare hematological neoplasm most often diagnosed in children and is commonly associated with Down's syndrome (DS). Although AMegLs are specifically characterized and typically diagnosed by megakaryoblastic expansion, recent advancements in molecular analysis have highlighted the heterogeneity of this disease, with specific cytogenic and genetic alterations characterizing different disease subtypes. Areas covered: This review will focus on describing recurrent molecular variations in both DS and non-DS pediatric AMegL, their role in promoting leukemogenesis, their association with different clinical aspects and prognosis, and finally, their influence on future treatment strategies with a number of specific drugs beyond conventional chemotherapy already under development. Expert opinion: Deep understanding of the genetic and molecular landscape of AMegL will lead to better and more precise disease classification in terms of diagnosis, prognosis, and possible targeted therapies. Development of new therapeutic approaches based on these molecular characteristics will hopefully improve AMegL patient outcomes.

Acute Megakaryoblastic Leukemia (AMKL) is a subtype of acute myeloid leukemia triggered by megakaryocytes. Acute megakaryoblastic leukemia is divided into three groups, AMKL in children with Down syndrome (DS-AMKL), AMKL in children who do not have Down Syndrome (non-DS-AMKL), and AMKL in non-DS adults (AMKL adults).The basis of the diagnosis of AMKL or AML-M7, according to FAB, is the presence of megakaryocyte line cells as many as 30% or more of all cells. Meanwhile, the diagnosis of AMKL, according to the 2016 WHO guidelines, is acute leukemia with blasts, about > 20%, > 50% of which is megakaryocyte line cells. Megakaryocyte cells can be more clearly seen with electron microscopes that react positively to platelet peroxidase or use marker antibodies to CD41/gpIIb, CD42b/gpIb, CD61/gpIIIa, von Willebrand factors, and linker for T cell activation.Based on the results of this research, there are differences in cytogenetics between the three types of AMKL according to their different pathophysiology. The World Health Organization (WHO) argued that AMKL was categorized into not otherwise specific (NOS) AML criteria. These criteria exclude AML with myelodysplasia (AMLMRC), AML associated with therapy, and AML with recurrent genetic abnormalities, such as AML with t (1; 22) (p13.3; q13.1), inv (3) (q21.3q26.2), or t (3; 3) (q21.3; q26.2). DS-AMKL is also classified into myeloid leukemia associated with DS. In conclusion, AMKL in adults is not only considered as a rare subtype of AMKL, only 1% of AML cases in population-based clinical experiments and data but also has a poor prognosis.

Acute megakaryoblastic leukemia is a rare subtype of pediatric acute myeloid leukemia (AML) with poor outcomes in patients with non-Down syndrome. The reported outcomes have been poor, and the prognostic factors have not been clearly determined.To evaluate the prognostic significance of various cytogenetic abnormalities and minimal residual disease status determined by flow cytometry after induction I, we retrospectively analyzed the data of 80 patients with non-Down syndrome with a diagnosis of M7 AML treated at Children's Cancer Hospital Egypt (CCHE-57357) from July 2007 through December 2016.Of the 80 patients, 15 died during induction I and were excluded from the survival analysis. The overall survival, event-free survival, and cumulative incidence of relapse at 2 years was 52.6% ± 12.7%, 45.2% ± 12.3%, and 31.8% ± 11.5% respectively. Of the 90 patients, 61 had cytogenetic abnormalities, including trisomy 19,13q, trisomy 8, complex karyotype, t(1;22), KMT2A rearrangements, and trisomy 21. None of these had an effect on the outcomes. In addition, 34 patients had minimal residual disease 0.1% after induction I, but the difference did not reach statistical significance. Patients with a delayed time to recovery (possibly due to myelofibrosis) had worse outcomes compared with those with early recovery (47% ± 19.2% vs. 63.2% ± 21.9%, respectively).Acute megakaryoblastic leukemia in patients with non-Down syndrome has a poor outcome with no clearly defined prognostic factors. However, future directions to risk stratify and tailor therapy should include assessment of the tumor biology according to the molecular pathways and study of the pathogenesis of myelofibrosis in this disease, which could affect the prognosis.

We report the case of a 3-year-old girl diagnosed with acute megakaryoblastic leukemia, who presented after >1 year of bilateral leg pain. At times the pain was severe enough to prevent ambulation, prompting visits to her primary care provider. However, it was not until acute respiratory failure occurred with subsequent hospitalization in the pediatric intensive care unit that severe anemia and thrombocytopenia were discovered and the diagnosis of acute myeloid leukemia was made. Bilateral lower extremity swelling was noted on admission and radiographs showed diffusely abnormal appearance of the long bones of her lower extremities with periosteal reaction and echogenic debris in the subperiosteal space, thought to represent leukemic cells. This case highlights the importance of recognizing atypical signs and symptoms of myelodysplastic syndrome progressing to acute leukemia in the context of abnormal bone pain and radiographic changes.

International audience; Pediatric acute myeloid leukemia is a rare and heterogeneous disease in relation to morphology, immunophenotyping, germline and somatic cytogenetic and genetic abnormalities. Over recent decades, outcomes have greatly improved, although survival rates remain around 70% and the relapse rate is high, at around 30%. Cytogenetics is an important factor for diagnosis and indication of prognosis. The main cytogenetic abnormalities are referenced in the current WHO classification of acute myeloid leukemia, where there is an indication for risk-adapted therapy. The aim of this article is to provide an updated review of cytogenetics in pediatric AML, describing well-known WHO entities, as well as new subgroups and germline mutations with therapeutic implications. We describe the main chromosomal abnormalities, their frequency according to age and AML subtypes, and their prognostic relevance within current therapeutic protocols. We focus on de novo AML and on cytogenetic diagnosis, including the practical difficulties encountered, based on the most recent hematological and cytogenetic recommendations.

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.

Simple Summary Infant acute myeloid leukemia (AML) is a rare subgroup of AML of pediatric patients under two years of age. For a long time, they have been included in pediatric forms of AML. However, infant AML demonstrates unusual clinical and biological characteristics, and its prognosis differs from AML in older children. Most treatment protocols do not distinguish age subgroups in pediatric AML, when in reality these unusual forms of infancy might benefit from specific targeted therapeutics. Herein we summarize the various specificities of infant AML. Abstract Infant acute myeloid leukemia (AML) is a rare subgroup of AML of children

Integrating somatic mutation analysis and gene expression profiling distinguishes pediatric AML subtypes with differential prognoses and clinical risks., Genomic characterization of pediatric patients with acute myeloid leukemia (AML) has led to the discovery of somatic mutations with prognostic implications. Although gene-expression profiling can differentiate subsets of pediatric AML, its clinical utility in risk stratification remains limited. Here, we evaluate gene expression, pathogenic somatic mutations, and outcome in a cohort of 435 pediatric patients with a spectrum of pediatric myeloid-related acute leukemias for biological subtype discovery. This analysis revealed 63 patients with varying immunophenotypes that span a T-lineage and myeloid continuum designated as acute myeloid/T-lymphoblastic leukemia (AMTL). Within AMTL, two patient subgroups distinguished by FLT3-ITD and PRC2 mutations have different outcomes, demonstrating the impact of mutational composition on survival. Across the cohort, variability in outcomes of patients within isomutational subsets is influenced by transcriptional identity and the presence of a stem cell–like gene-expression signature. Integration of gene expression and somatic mutations leads to improved risk stratification. Significance: Immunophenotype and somatic mutations play a significant role in treatment approach and risk stratification of acute leukemia. We conducted an integrated genomic analysis of pediatric myeloid malignancies and found that a combination of genetic and transcriptional readouts was superior to immunophenotype and genomic mutations in identifying biological subtypes and predicting outcomes. This article is highlighted in the In This Issue feature, p. 549

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia but is approximately 500 times more likely to develop in children with Down syndrome (DS) through transformation of transient abnormal myelopoiesis (TAM). This study investigates the clinical significance of genomic heterogeneity of AMKL in children with and without DS and in children with TAM. Genomic evaluation of nine patients with DS-related TAM or AMKL, and six patients with non-DS AMKL, included conventional cytogenetics and a comprehensive next-generation sequencing panel for single-nucleotide variants/indels and copy-number variants in 118 genes and fusions involving 110 genes. Recurrent gene fusions were found in all patients with non-DS, including two individuals with complex genomes and either a NUP98–KDM5A or a KMT2A–MLLT6 fusion, and the remaining harbored a CBFA2T3–GLIS2 fusion, which arose from both typical and atypical cytogenetic mechanisms. These fusions guided treatment protocols and resulted in a change in diagnosis in two patients. The nine patients with DS had constitutional trisomy 21 and somatic GATA1 mutations, and those with DS-AMKL had two to four additional clinically significant somatic mutations. Comprehensive genomic characterization provides critical information for diagnosis, risk stratification, and treatment decisions for patients with AMKL. Continued genetic and clinical characterization of these rare cancers will aid in improving patient management.

A 59-year old gentleman with transformation of myelodysplastic syndrome to acute megakaryoblastic leukemia was treated with standard intensive chemotherapy. His poor outcome was attributed to advanced age, aggressive disease biology, underlying myelodysplastic syndrome, poor response to induction chemotherapy, high lactate dehydrogenase and lack of good cytogenetic and molecular mutations.

Transient abnormal myelopoiesis (TAM) is a unique clonal myeloproliferation characterized by immature megakaryoblasts that occurs in 5–10% of neonates with Down syndrome (DS). Although TAM regresses spontaneously in most patients, approximately 20% of TAM cases result in early death, and approximately 20% of survivors develop acute megakaryoblastic leukemia (AMKL). We retrospectively reviewed records of 35 DS patients with TAM to determine the correlation between clinical characteristics and blast percentage. Thirteen of the 35 patients were classified as low blast percentage TAM (LBP-TAM), defined as TAM with a peak peripheral blast percentage ≤ 10%. Although no patient with LBP-TAM experienced systemic edema, disseminated intravascular coagulation, or early death, eight patients had elevated direct bilirubin levels (> 2 mg/dl) and one developed AMKL. All patients with LBP-TAM had serum markers of liver fibrosis that exceeded the normal limits, and two patients underwent liver biopsy to clarify the etiology of pathological jaundice. Taken together, our results suggest that patients with LBP-TAM may be at risk of liver fibrosis and liver failure, similarly to patients with classical TAM. Although these patients generally have a good prognosis, they should be carefully monitored for potential development of liver disease and leukemia.

Background There is no established effective treatment for patients with t(1;22)(p13;q13) acute megakaryoblastic leukemia (AMKL) and hepatic fibrosis. Observation Here we report the outcomes of 2 t(1;22)(p13;q13) AMKL patients with hepatic fibrosis. One patient died from liver failure despite the control of leukemia. The other patient was successfully treated with reduced-intensity chemotherapy and antifibrosis therapy with tretinoin and α-tocopheryl acetate, the hepatic fibrosis resolved and leukemia was in remission for 3 years. Conclusions Reduced-intensity chemotherapy plus antifibrosis therapy with tretinoin and α-tocopheryl acetate could be a treatment option for these patients with t(1;22)(p13;q13) AMKL and hepatic fibrosis.

Pediatric acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia (AML) that may be divided into two subgroups: (1) Down syndrome- (DS-) related AMKL which generally has a favorable prognosis and (2) non-DS-related AMKL which generally has a poorer outcome. We report a phenotypically normal child with AMKL with trisomy 21 (T21) and tetrasomy 21 clones. Subsequently, she was diagnosed with mosaic T21. She underwent reduced-intensity therapy with good outcome. We review the literature regarding AMKL-associated cytogenetic abnormalities and AMKL in association with DS. We suggest evaluation for mosaic T21 in phenotypically normal pediatric patients with T21-positive AML.

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.

This case report presents a 14-month-old female Poodle mix with acute megakaryoblastic leukemia based on a marked thrombocytosis, abnormal platelet morphology, circulating dwarf megakaryocytes, and blast cells in the blood. Bone marrow abnormalities included dysmegakaryopoiesis dygranulopoiesis, and an increased number of blast cells was observed in the blood. Extensive leukemic involvement was also found in the liver, spleen, lymph nodes, lungs, kidneys, and brain. The cytopathologic features of the abnormal circulating cells were highly suggestive of being megakaryocytic in origin, which was supported by negative myeloperoxidase staining and positive von Willebrand factor staining on immunocytochemistry (ICC). The neoplastic cells were also CD61 positive and had variable von Willebrand factor expression on ICC. Although there were only 25% blast cells in the bone marrow, which theoretically supported myelodysplastic syndrome, the hypothesis that this case represented acute myeloid leukemia of megakaryoblastic origin was confirmed by the continuous increase in circulating blast cell numbers during follow-up visits and the extensive leukemic involvement of parenchymal organs.

Pathologic increase in bone marrow reticulin fibrosis can be present in many malignant hematopoietic diseases. In acute leukemia, one-third of patients have some degree of marrow reticulin fibrosis at presentation, which is thought to be related to cytokine release from blasts. Marrow fibrosis is particularly common in acute megakaryoblastic leukemia, while this change is rarely seen in acute promyelocytic leukemia. Six case reports of acute promyelocytic leukemia with marrow reticulin fibrosis have been described so far in the literature. Herein, we present three cases of classical acute promyelocytic leukemia with increased marrow reticulin fibrosis encountered in our institution, summarizing their clinicopathologic features, treatment, and outcome to date. Awareness of the features of acute promyelocytic leukemia with marrow reticulin fibrosis is important as it may guide treatment options. Keywords: Acute promyelocytic leukemia, Bone marrow, Case report, Fibrosis, Reticulin, Review

An 87-year-old woman not known to have either a lymphoma or leukemia developed a left multinodular, fish-flesh superior epibulbar and forniceal mass. A biopsy disclosed a blastic tumor with scattered multinucleated immature megakaryoblasts. Immunophenotyping of bone marrow cells revealed strong positivity for CD7, CD31, CD43, CD45, CD61, and CD117; CD71, myeloperoxidase, and lysozyme were also positive in scattered cells. Forty percent of the neoplastic cells were Ki-67 positive. Cytogenetic studies indicated a trisomy 8 (associated with worse prognosis) and a t(12; 17) translocation. Desmin, smooth muscle actin, pancytokeratin, CAM 5.2, adipophilin, tryptase, S100, SOX10, MART1, and E-cadherin were negative, ruling out a nonhematopoietic tumor. The conjunctival lesion was diagnosed as a myeloid sarcoma with megakaryoblastic differentiation, a rare variant. It probably arose from a myelodysplastic syndrome. This is the first case of its type to develop in the conjunctiva.

Acute Megakaryoblastic Leukemia (FAB AML M7) occurs in all age groups with two peaks in distribution. The one is in adults and theother in children 1 to 3 years of age especially in those with Down's syndrome. The diagnosis of AML M7 requires more than 30% of thenucleated bone marrow cells being megakaryoblasts. The AML M7 was under diagnosed before the availability of monoclonal antibodies.The more common types of AML MO-M6 have to be excluded by morphological and cytochemical analysis whereas immunology is neededto exclude ALL. The megakaryocytic nature of the leukemia has to be proven by ultrastructural demonstration of platelet peroxidase or byimmunological demonstration of CD61, CD42, CD41 on the surface of the leukemic blasts. Megakaryocytic/megakaryoblastic leukemiasshow a wide morphologic spectrum. Cytoplasmic blebs and protrusions are the most prominent feature of many cases. The nuclei ofthese cells are round with more finely reticulated chromatin and with prominent nucleoli. The megakaryoblastic nature of these cells canbe suggested by morphology. Cytochemistry is of limited diagnostic value in megakaryoblastic leukemias. Usually it is used to excludethe more common types of leukemia. An eighteen months girl was admitted to hospital with anemia and hepatosplenomegaly. There isdismorphic - hypertelorism face and enlargement of neck lymph nodes. The laboratory examination found anemia, hyperleukocytosis with75 % blast cells. Morphologically the blast cells show prominent blebs and cytoplasmic budding resemble features of budding platelets.The cytochemistry staining for granulocyte and erythrocyte lineages were negative. The expressions of lymphoid and myeloid lineagesmarkers by immunoflowcytometry method were also negative. Cytogenetic examination was followed. The physical and laboratoryexamination result conclude a child with Acute Megakaryoblastic Leukemia. Cytogenetic examination was followed

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.

Background The functions of the HOXA 5, HOXA 9, and PRDM16 are concerned with embryonic growth and the regulation of adult hematopoietic cells differentiation. The HOXA5, HOXA9, and PRDM16 are expressed in the majority of solid cancers and several hematological malignancies, including myeloproliferative disease and acute leukemia. The function and prognostic values of HOXA5, HOXA9, and PRDM16 quantitative PCR expression in novel patients with acute myeloblastic leukemia (AML) were to be studied. Methods This prospective case-control study was performed on 60 newly diagnosed AML patients and 40 healthy subjects acting as a control group. The patients underwent CBC, BM analysis, HOXA5, HOXA9, and PRDM16 expression by qRT-PCR testing. Results High expressions of HOXA5, HOXA9, and PRDM16 were significantly prevalent in patients compared with the control. The highest incidence of expression was found in AML patients with minimal maturation and acute megakaryoblastic leukemia (M1/M7). Interestingly, high levels of HOXA5, HOXA9, and PRDM16 expressions were correlated with older age and hepatosplenomegaly associated with poor clinical outcome, shorter overall and disease-free survival than low levels of HOXA5, HOXA9, and PRDM16 expressions. Conclusion High HOXA and PRDM16 expressions predict bad outcomes and are associated with weak prognostic factors which can promote new therapeutic trends for AML.

Objective Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia (AML) associated with poor prognosis for all patients except children with t(1;22) or Down syndrome. The frequency of complete remission in case of AMKL is comparable to the frequency of it in other variants of AML but the median survival is much lower. This determines the necessity of more thorough evaluation of treatment effect using flow cytometry accessment of minimal residual disease (MRD). Methodology The clinical and immunological profile of 8 girls and 9 boys with de novo AMKL between the ages of 3 months–11 years old was analyzed. The primary leucocytosis median was 10,25; only one patient had hyperleukocytosis (53х109/l) at presentation.The measurement of MRD was performed in 6 patients using multiparameter flow cytometry. The measurement of MRD performed after induction therapy on the basis of megakaryocytic markers, weak CD45 expression using the initial iimmunophenotype patterns. Results Adequate measurement of the level of MRD had required extensive diagnostic immunophenotyping in order to determine the aberration of megakaryoblasts. CD9(83,3%), CD33(75%), CD34(60%), CD13(50%) apart from megakaryocyte markers (100%) were most common for blast cells in case of AMKL. The expression of CD7 antigen was as frequent as of CD117-40%. The MRD level ranged from completely negative (0%; 0.006%) to evident (1.05%). Conclusion The detection of residual tumor megakaryoblasts in AML M7 using flow cytometry is a promising method for assessing the effect of therapy. Adequate measurement of MRD requires detailed immunophenotyping in the diagnosis to determine the aberrations of megacaryoblasts immunophenotype.

The association between mediastinal germ cell tumors (MGCT) and acute megakaryoblastic (M7) leukemia has been known for many years. We hereby present this review to better characterize the coexistence of these entities as well as the salient features, the treatment options, and the overall prognosis. A search of PUBMED, Medline, and EMBASE databases via OVID engine for primary articles and case reports under keywords "germ cell tumors" and "acute myeloid leukemia" revealed a total of 26 cases in English that reported MGCT and M7 leukemia. The median age at diagnosis of MGCT was 24 (13-36) years. All cases were stage III. All cases of MGCT were of non-seminomatous origin and one case was unclassified. MGCT occurred prior to the diagnosis of leukemia in 46% of cases and concomitantly in 31% of cases. M7 leukemia was never reported prior to the appearance of MGCT. Complex cytogenetics and hyperdiploidy were the most commonly reported cytogenetic abnormalities. In the 23 cases where the treatment regimen was available, platinum-based chemotherapy directed towards management of the germ cell tumors was used initially in 21 cases and leukemia-directed treatment was used initially in 2 cases only. The median time from diagnosis of MGCT to development of M7 leukemia was 5 (2.25-39) months. Median time to death from the initial diagnosis of MGCT was 6 (0.5-60) months. Patients with a history of MGCT are at higher risk of developing M7 leukemia. They need long-term follow-up with a particular attention to the development of hematological malignancies. The overall prognosis remains poor.

Acute megakaryoblastic leukemia (AMKL) in children without Down syndrome (DS) has an extremely poor outcome with 3-year survival of less than 40%, whereas AMKL in children with DS has an excellent survival rate. Recently, a novel recurrent translocation involving CBFA2T3 and GLIS2 was identified in about 30% of children with non-DS AMKL, and the fusion gene was reported as a strong poor prognostic factor in pediatric AMKL. We report the difficult clinical courses of pediatric patients with AMKL harboring the CBFA2T3-GLIS2 fusion gene.Down sendromu (DS) olmayan çocuklarda akut megakaryoblastik löseminin (AMKL) prognozu çok kötü ve 3 yıllık sağkalım %40’ın altında iken, DS’li çocuklarda AMKL’nin sağkalım oranı mükemmeldir. Yakın zamanda, DS olmayan AMKL’li çocukların yaklaşık %30’unda CBFA2T3 ve GLIS2’yi içeren yeni bir tekrarlayan translokasyon tanımlandı ve füzyon geninin pediatrik AMKL olgularında kötü prognoz ile ilişkili güçlü bir prognostik belirteç olduğu bildirildi. CBFA2T3-GLIS2 füzyon genini taşıyan AMKL tanılı pediatrik hastalarda sorunlu klinik seyri bildiriyoruz.

Acute myeloid leukemia has a rare subtype in French-American-British classification as M7 or acute megakaryoblastic leukemia. Chromosome abnormalities in cases with acute megakaryoblastic leukemia can affect their prognosis. Evaluation of these abnormalities and their impact are not fully elucidated. This case presentation is about 16 months female who has a rare abnormality (trisomy 3) alongside acute megakaryoblastic leukemia. The remarkable point is that her malignancy is as primary or non-Down syndrome acute megakaryoblastic leukemia. The author's suggestion through this case presentation is the necessity of drawing a cytogenetic profile, especially in cases with acute megakaryoblastic leukemia for better treatment strategies.

Background Acute myeloid leukemia (AML) is a heterogeneous disease regarding morphology, immunophenotyping, genetic abnormalities, and clinical behavior. The overall survival rate of pediatric AML is 60% to 70%, and has not significantly improved over the past two decades. Children with Down syndrome (DS) are at risk of developing acute megakaryoblastic leukemia (AMKL), which can be preceded by a transient myeloproliferative disorder during the neonatal period. Intensification of current treatment protocols is not feasible due to already high treatment‐related morbidity and mortality. Instead, more targeted therapies with less severe side effects are highly needed. Procedure To identify potential novel therapeutic targets for myeloid disorders in children, including DS‐AMKL and non‐DS‐AML, we performed an unbiased compound screen of 80 small molecules targeting epigenetic regulators in three pediatric AML cell lines that are representative for different subtypes of pediatric AML. Three candidate compounds were validated and further evaluated in normal myeloid precursor cells during neutrophil differentiation and in (pre‐)leukemic pediatric patient cells. Results Candidate drugs LMK235, NSC3852, and bromosporine were effective in all tested pediatric AML cell lines with antiproliferative, proapoptotic, and differentiation effects. Out of these three compounds, the pan‐histone deacetylase inhibitor NSC3852 specifically induced growth arrest and apoptosis in pediatric AML cells, without disrupting normal neutrophil differentiation. Conclusion NSC3852 is a potential candidate drug for further preclinical testing in pediatric AML and DS‐AMKL.

Various conditions can lead to antenatal hepatosplenomegaly. In addition to commonly known etiologies like hydrops fetalis or viral illnesses, hematologic disorders like congenital leukemia, although rare, should also be ruled out. We present a case of hepatosplenomegaly detected during antenatal screening in a neonate, in whom acute megakaryoblastic leukemia was diagnosed postnatally based on the immunophenotype.

Congenital leukemia is rare disease with an incidence of one to five cases per million births. Transient abnormal myelopoiesis (TAM), also called transient myeloproliferative disorder, is a pre-leukemia disorder that may occur in Down syndrome (DS) or non-DS infants. TAM may enter spontaneous remission; however, continual monitoring is required, as this disorder has been observed to develop into acute megakaryoblastic leukemia in 16-30% of cases. In the literature, 16 cases of TAM in non-DS infants have been reported. The case presented in the current study is, to the best of our knowledge, the first case of an Italian non-DS newborn presenting with clinical manifestations of acute leukemia at five days after birth, exhibiting a normal karyotype, trisomy 21 only in blast cells, and spontaneous remission. Chromosomal analyses on peripheral blood cells, bone marrow cells and dermal fibroblasts were conducted using a G-banding technique, and fluorescence in situ hybridization (FISH) was used to identify the critical regions of DS. Amplification of GATA binding protein 1 (GATA1) exon 2 genomic DNA was performed using polymerase chain reaction. Cytogenetic analysis of 50 peripheral blood cells and dermal fibroblasts from the patient revealed a normal karyotype: 46, XX. Conversely, cytogenetic analysis of the patient's bone marrow revealed an abnormal karyotype 47, XX+21. In order to investigate this result, FISH was performed, which identified the presence of three signals in 70% of the cells and two signals in 30% of bone marrow cells. GATA1 sequencing revealed the substitution of a single base (c.150delG) in exon 2. Seven months after the initial analysis, FISH and cytogenetic analyses of the stimulated/unstimulated peripheral blood cells and bone marrow cells were performed, revealing that each exhibited diploid signals, as observed in a normal karyotype.

Acute erythroid leukemia (FAB-M6) and acute megakaryoblastic leukemia (FAB-M7) exhibit closely related properties in cells regarding morphology and the gene expression profile. Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered the mainstay of the treatment for both subtypes of leukemia due to their refractoriness to chemotherapy and high rates of relapse, it remains unclear whether allo-HSCT is curative in such cases due to their scarcity. We retrospectively examined the impact of allo-HSCT in 382 patients with M6 and 108 patients with M7 using nationwide HSCT data and found the overall survival (OS) and relapse rates of the M6 patients to be significantly better than those of the M7 patients after adjusting for confounding factors and statistically comparable with those of the patients with M0/M1/M2/M4/M5 disease. Consequently, the factors of age, gender, performance status, karyotype, disease status at HSCT and development of graft-vs.-host disease predicted the OS for the M6 patients, while the performance status and disease status at HSCT were predictive of the OS for the M7 patients. These findings substantiate the importance of distinguishing between M6 and M7 in the HSCT setting and suggest that unknown mechanisms influence the HSCT outcomes of these closely related subtypes of leukemia. © 2016 Elsevier Ltd., Embargo Period 12 months

Acute megakaryocytic leukemia is a rare form of acute myeloid leukemia that carries a poor prognosis. As most cases of osteolytic lesions are due to plasma cell and myeloid malignancies, maintaining a broad differential directly influences clinical course. We document a 45-year-old patient with progressive constitutional symptoms, osteolytic bone lesions in the setting of hypercalcemia, who developed acutely worsening pancytopenia. The diagnosis of myeloid sarcoma with megakaryocytic differentiation was made after obtaining tissue from osteolytic bone that stained strong for CD34. Immunohistochemical testing underscores the importance of how serologic and urine testing remains limited and can delay early diagnosis in this disease. Keywords: myelofibrosis; AML; acute panmyelosis; acute megakaryoblastic leukemia (Published: 25 April 2016) Citation: Journal of Community Hospital Internal Medicine Perspectives 2016, 6 : 30327 - http://dx.doi.org/10.3402/jchimp.v6.30327

Context Acute megakaryoblastic leukemia (AMKL) is a rare myeloid leukemia, occurring in 1%–5% of all adult acute myeloid leukemia (AML) cases. AMKL is characterized by a leukemic blast population positive for factor VIII, CD41a, CD42b, and/or CD61 with extensive myelofibrosis. Although various cytogenetic abnormalities are commonly reported, the association between constitutional trisomy 21 and AMKL has been of particular interest, because of the near universal presence of GATA1 mutation in such cases. Objective and Design We report a case of AMKL in an adult presenting with extensive bone marrow necrosis in which cytogenetic studies revealed three copies of chromosome 21 as part of a complex karyotype; however, sequencing of the GATA1 gene revealed no mutation. Results The patient was an adult male who presented with extensive bone marrow necrosis, making definitive diagnosis difficult. Autopsy studies using a multimodality approach identified AMKL with a complex karyotype, including trisomy 21. Sanger sequencing of the GATA1 gene showed a germline configuration without a mutation. Conclusions To our knowledge, this is the first reported case of an adult with AMKL with acquired trisomy 21 in which the GATA1 mutation was investigated and the second reported case of AMKL presenting with extensive bone marrow necrosis. We will present a diagnostic approach to AMKL in which extensive bone marrow necrosis renders examination of the bone marrow difficult. Furthermore, we will examine the absence of the GATA1 mutation in a case of AMKL with trisomy 21 in an adult.

Background/purpose Although Down syndrome (DS) patients have a higher risk of developing transient myeloproliferative disorder (TMD) and acute leukemia, very little data is available on long-term outcome in Taiwanese patients. The current study was designed to determine the clinical characteristics and treatment outcome of DS patients with TMD or acute leukemia (AL). Methods In 25 consecutive DS patients with TMD or AL enrolled from 1990 to 2012, clinical manifestations and treatment protocols were investigated and GATA1 (GATA binding protein 1) mutations were identified. Among 16 DS-acute myeloid leukemia (DS-AML) patients, clinical outcomes were compared between survivors and nonsurvivors. Results Most of our DS patients had TMD (32%), acute megakaryoblastic leukemia (24%), or acute erythromegakaryoblastic leukemia (16%). The median follow-up time was 22.5 months (1–230 months). The age was younger and the hemoglobin (Hb) level and platelet count were higher in TMD patients than in leukemia patients. Among DS-AML patients, the Hb level was higher in survivors than nonsurvivors (8.8 ± 2.7 g/dL vs. 5.8 ± 2.4 g/dL; p = 0.044) and the age was older in relapsed patients than in nonrelapsed patients (43.8 ± 18 months old vs. 21.6 ± 8.6 months old; p = 0.025). The 3-year overall survival (OS) rate was 44%, higher in patients receiving appropriate chemotherapy than in those receiving inadequate treatment (63.6% vs. 0%, p = 0.001), and higher in those diagnosed with TMD or AL after 2008 than before 2008 (33.3% vs. 75%; p = 0.119). Conclusion Outcome in DS-AML patients is optimal if appropriate treatment is provided. With modification of the treatment strategy in 2008, OS increased in Taiwan.

Acute megakaryoblastic leukemia (AMKL) is a rare disease accounting for 7%–10% of acute myeloid leukemia (AML) in children. It is uncommon in children without Down syndrome (DS). Orbital chloroma is usually associated with AML M2, M4, and M5. Herein, we report the case of a 22-month-old female who was diagnosed to have AMKL with orbital chloromas and without DS. Morphology and the initial panel of immunophenotyping were inconclusive and the presence of orbital chloromas added to the ambiguity. The presence of CD61 expression and marrow fibrosis supported by hyperdiploidy helped us clinch the diagnosis. Hence, comprehensive analysis of morphology, immunophenotyping, and cytogenetics is warranted to make an accurate diagnosis of AMKL.

In this study, we aimed to characterize the molecular mechanisms of two very rare subtypes of AML: acute megakaryoblastic leukemia (AMKL) and acute panmyelosis with myelofibrosis (APMF). Our goal is to describe the clinical-pathologic features of APMF and explore the genomic landscape AMKL to further understand these rare malignancies. We identified 35 patients diagnosed with AMKL (n=27) and APMF (n=8) at Mayo Clinic between 1995 and 2015 by retrospective chart review. For 10 of the AMKL patients, tissue was available for whole-exome sequencing and was analyzed in comparison to a published AML reference population. The median overall survival was shorter in patients with AMKL (3.9 months, 95% CI 1.7-7.4) than in patients with APMF (14.3 months, 95% CI 0.7-NE, p = 0.026,). For both AMKL and APMF, patients who underwent allogeneic hematopoietic stem cell transplantation had better overall survival (14.3 months, 95% CI 1.9-NE) compared to those not undergoing transplantation (4.6 months, 95% CI 1.5-7.4, p = 0.003). Patients with AMKL presented more frequently with splenomegaly, with higher peripheral blood blast counts, and with higher serum lactate dehydrogenase concentrations. 9 out of 10 AMKL patients with available tissue for sequencing demonstrated variants in 22 of 35 AML driver genes, with JAK2 V617F as the most common mutation. Although our small study numbers preclude firm conclusions, it does reflect the rarity of these AML subtypes. Furthermore, inferior survival in AMKL (compared to APMF) was reflected in its proliferative disease features such as splenomegaly, high blast counts, and high lactate dehydrogenase. Interestingly, the presence of JAK2 V617F variants in 40% of the interrogated samples was higher than expected. Although JAK2 is a known molecular driver in myeloproliferative neoplasms, it is actually very rare in de novo AML (~1%). Despite improved survival with allogeneic stem cell transplant, we can conclude that treatment outcomes for AMKL and APMF with standard-of-care therapy were sobering and that patients with these rare AML subtypes should undergo molecular evaluation to qualify them for clinical trials with novel targeted therapies. Citation Format: Marissa Li, Moritz Binder, Basma Basha, Ben Zhang, Alejandro Ferrer, Yuanhan Liu, Mrinal Patnaik, David Viswanatha, Naseema Gangat. Acute megakaryoblastic leukemia is associated with poor overall survival and enriched in JAK2 variants [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr B03.