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At least 19 recordsLinked to original sources
PubMed2004

Occurrence of a variant Philadelphia translocation, t(10;22), in de novo acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia (AMegL) in adults is a very rare subtype of acute myeloid leukemia (AML) and is characterized by a larger diversity of chromosomal abnormalities than the other subtypes, including 3q21q26 changes, aberrations of chromosomes 5 and 7, and the t(9;22)(q34;q11). We report the case of a 24-year-old patient with de novo AMegL and thrombocythemic cell count. Diagnosis was established with a bone marrow biopsy, and cytogenetics with G-banding revealed a t(10;22), which by FISH, was found to be a variant Philadelphia translocation involving chromosome 10q in all 20 metaphases analyzed. We believe that this is the first report of de novo AMegL with this chromosomal abnormality, and its possible correlation with morphology and thrombocytosis is discussed.

Adult↗
PubMed1997

Characteristics of a cell line established from a case of acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia is uncommon and comprises about 5% of acute nonlymphoid leukemias in the French-American-British classification. Cell lines from such leukemias are relatively rare with only about 8 reported in the literature. We established a cell line from a case of acute megakaryoblastic leukemia arising in a 2-year-old child. Surface marker studies of the cells confirmed their megakaryoblastic nature, with 54% of the cells being CD61 positive and peroxidase and esterase negative. The cells had a doubling time of 72 h. Emperipolesis (a phenomenon in which a cell, usually a lymphocyte or neutrophil, enters another cell, moves about and leaves without undergoing phagocytosis) of one blast into another, larger one, was occasionally seen, and a review of the original bone marrow specimen also showed emperipolesis of neutrophils into the megakaryoblasts. The cells responded to interleukin 3 and were inhibited with all-trans-retinoic acid. The karyotype of the cells was the 46,XX,-16 with a marker chromosome. The marker chromosome is possibly chromosome 16 with a small segment of a chromosome translocated to the terminal portion of chromosome 16.

Antigens, CD↗
PubMed1989

Myeloperoxidase-positive acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia (FABM7) is an unusual but well recognized form of acute myelogenous leukemia in which the bone marrow blast cells are phenotypically recognized by the demonstration of cytoplasmic platelet peroxidase or surface staining for the IIb/IIIa platelet-specific glycoprotein. Herein, the authors report a case of acute megakaryoblastic leukemia that satisfies the accepted French-American-British criteria and in which the blast cells also exhibit evidence of myeloid differentiation, including surface MY7 (CD13) by flow cytometry and immunocytochemical positivity for myeloperoxidase. These findings suggest that megakaryoblasts may be closely related to myelomonoblasts, that they have the potential to partially differentiate along multiple phenotypic lines, and that aberrant phenotypes can occur that do not correspond to known stages of normal maturation. The authors illustrate the difficulty in classification of these aberrant phenotypes by standard cytochemical and morphologic criteria.

Cell Membrane↗
PubMed1990

Target cell of leukemic transformation in acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia (AMkL) is a newly defined acute leukemia in which the differentiation of proliferating blasts is arrested at the megakaryocytic precursor stage. In order to clarify whether a target cell of leukemic transformation in AMkL is a cell committed to megakaryocytic lineage, or a multipotential stem cell, we examined AMkL patients with regard to: a) the presence of myelodyplastic features in residual erythroid and granulocytic cells, b) coexistence of myeloperoxidase (MPO)-positive blasts with megakaryoblasts, and c) the presence of the same chromosomal abnormality in erythroid and granuloid colony-forming cells as seen in megakaryoblasts. Regarding the former two items, results were compared with those from megakaryoblastic crisis of chronic myelocytic leukemia (CML-MkBC) and transient myeloproliferative disorder in Down syndrome (DS-TMD), which are thought to be multipotential stem cell disorders. Among 18 patients with AMkL, three, all complicating myelofibrosis, had marked myelodysplastic changes of erythroid series and/or granulocytic series. In 4 out of 7 patients with CML-MkBC, 5 out of 8 patients with DS-TMD, and 7 out of 18 patients with AMkL, MPO-positive blasts, even though rare, were observed in addition to PPO-positive blasts. All except one of these patients with AMkL also showed complicating myelofibrosis. In one case of AMkL with myelofibrosis, chromosomal analysis of cultured cells of individual colonies revealed that all the analysable metaphases from both CFU-GM and BFU-E had the same chromosomal abnormality as megakaryoblasts. This study has clarified that a considerable proportion of AMkL cases, particularly those with complicating myelofibrosis or showing acute myelofibrosis, arise against the background of a multipotential stem cell disorder, even if blasts are exclusively megakaryocytic in phenotype.

Cell Transformation, Neoplastic↗
PubMed1982

Acute megakaryoblastic Leukemia.

Acute megakaryoblastic leukemia is a rare and rapidly fetal disorder characterized by extensive proliferation of megakaryoblasts and atypical megakaryocytes in bone marrow and extramedullary sites, thrombocytopenia and only a few blasts in peripheral blood. Three cases of this leukemia were studied morphologically, cytochemically, and electron microscopically. The leukemia blasts varied from 10-20 mu in diameter, had coarsely reticular nuclear chromatin, and numerous cytoplasmic projections and vacuoles. Except for intense granular PAS positivity and diffuse acid phosphatase reactivity, all of the usual cytochemical stains were negative. The blasts had no specific differentiating features identifying them as megakaryoblasts even at the ultrastructural level. In such instances demonstration of platelet peroxidase will confirm the megakaryocytic origin. All three patients in this series were men and all died within 90 days. Two patients also had other malignancies.

Acute Disease↗
PubMed1984

Platelet dysfunction in acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia occurred in an adolescent. There was considerable bleeding despite only moderate thrombocytopenia, and both platelet structure and platelet function were abnormal. To our knowledge, platelet dysfunction has only once been documented in this acute leukemia, although in other leukemias with megakaryocytic predominance, notable bleeding has been observed in the absence of thrombocytopenia.

Adolescent↗
PubMed1982

Acute megakaryoblastic leukemia (acute "malignant" myelofibrosis): an unusual cause of osteosclerosis.

Acute megakaryoblastic leukemia or acute "malignant" myelosclerosis is an acute and rapidly progressive myeloproliferative syndrome characterized by minimal or absent splenomegaly, pancytopenia, diffuse marrow fibrosis, and circulating blasts of megakaryocytic origin. The disease must be differentiated from other hematologic malignancies especially myelofibrosis with myeloid metaplasia. The radiographic changes of osteosclerosis in our patient have not been previously reported in the literature.

Acid Phosphatase↗
PubMed1991

Dysmegakaryopoiesis resembling acute megakaryoblastic leukemia in treated acute myeloid leukemia.

Acute myeloid leukemia (AML) is characterized by trilineage dysplasia, including atypical megakaryocytes. Acute megakaryoblastic leukemia (FAB M7) is particularly associated with atypical megakaryocytic hyperplasia (AMH). Fifteen patients with nonmegakaryoblastic AML developed AMH after therapy, comprising 12.6% of cases of AML diagnosed from 1986 to 1989. Platelet counts were normal in nine patients and decreased in six. Blasts comprised less than 5% of cells in 40% of the biopsies, ranged from 5-15% in 53%, and comprised more than 30% of cells in 7%. Numerous small hypo- and hyperlobated megakaryocytes were seen in all specimens, often occurring in clusters, and were more easily seen in sections than in smears. Subsequent biopsies in 13 patients showed a remission marrow in seven, increased blasts in three, and AML in three; none showed AMH. AMH resembling acute megakaryoblastic leukemia may be seen transiently after treatment of AML.

Acute Disease↗
PubMed1998

Chronic myelogenous leukemia terminating in acute megakaryoblastic leukemia. Case report.

A case of chronic myelogenous leukemia (CML) terminating in acute megakaryoblastic leukemia (AMKL) is here presented. Megakaryoblasts were identified by the presence of platelet peroxidase in the bone marrow as well as in pleural effusion and ascites. The clinical course, morphology and immunologic studies of the blast cells are described in this report.

Abdomen↗
PubMed2003

GATA1 mutations in transient leukemia and acute megakaryoblastic leukemia of Down syndrome.

Children with constitutional trisomy 21 (Down syndrome) have an approximately 500-fold increased risk of developing acute megakaryoblastic leukemia (AMKL), a form of acute myeloid leukemia. Unique to newborn infants with Down syndrome is a transient leukemia (TL), also referred to as transient myeloproliferative syndrome, that undergoes spontaneous remission in the majority of cases but in approximately 20% is followed by AMKL later in life. Recently mutations of the gene encoding the hematopoietic transcription factor GATA1 were shown to be specific for AMKL of Down syndrome. Here, we demonstrate that GATA1 mutations are present in blasts of TL and show the identical GATA1 mutation in sequential samples collected from a patient during TL and subsequent AMKL. These findings suggest a model of malignant transformation in Down syndrome AMKL in which GATA1 mutations are an early event and AMKL arises from latent TL clones following initial apparent remission.

Cell Transformation, Neoplastic↗
PubMed1992

Acute megakaryoblastic leukemia simulating carcinoma.

Acute megakaryoblastic leukemia has emerged as an important subset of early childhood leukemia. It often presents a diagnostic dilemma because of its many morphologic manifestations and propensity to mimic metastatic carcinoma. An abdominal mass was identified by sonographic and computed tomographic scans in a 10-month-old girl, who had anemia and thrombocytopenia. An open biopsy of the 3-cm, peripancreatic mass showed cohesive nests and sheets of tumor cells with focal spindling and desmoplasia. Although the diagnosis of acute megakaryoblastic leukemia was established from a bone marrow aspirate using immunocytochemical techniques and karyotype analysis, a coexistent abdominal epithelial malignant neoplasm could not be excluded entirely by light microscopic examination alone. The megakaryoblastic nature of the abdominal tumor was established by immunocytochemical stains for glycoprotein IIIa on paraffin-embedded tissue.

Abdominal Neoplasms↗
PubMed1995

Acute megakaryoblastic leukemia.

In 1985 acute megakaryoblastic leukemia was included in the FAB classification system of hematological neoplasias with the designation of AML M7. It occurs in all age groups with two peaks in distribution. The one is in adults and the other 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 the nucleated bone marrow cells being megakaryoblasts. The more common types of AML MO-M6 have to be excluded by morphological and cytochemical analysis whereas immunology is needed to exclude ALL. The megakaryocytic nature of the leukemia has to be proven by ultrastructural demonstration of platelet peroxidase or by immunological demonstration of CD61, CD42, CD41 on the surface of the leukemic blasts. Megakaryocytic/megakaryoblastic leukemias show a wide morphologic spectrum. In some instance small cells dominate, clearly showing megakaryocytic differentiation with scant amounts of cytoplasm and with nuclei showing dense chromatin. On the other hand, there are cases with larger cells resembling ALL-L2 blasts with moderate amounts of rather basophilic cytoplasm which in some instances contain azurophilic granules. Cytoplasmic blebs and protrusions are the most prominent feature of many cases. The nuclei of these cells are round with more finely reticulated chromatin and with prominent nucleoli. The megakaryoblastic nature of these cells can be suggested by morphology. However, according to our experience there are cases of c-ALL with the very same morphologic picture. Consequently, immunologic phenotyping of these cases is necessary in any instance. Cytochemistry is of limited diagnostic value in megakaryoblastic leukemias. Usually it is used to exclude the more common types of leukemia.

Adult↗
PubMed2003

[Molecular basis of the t(1;22)(p13;q13) specific for human acute megakaryoblastic leukemia].

The t(1;22)(p13;q13) translocation is specifically associated with infant acute megakaryoblastic leukemia (M7). We have recently characterized the two genes involved in this translocation: OTT (One Two Two) and MAL (Megakaryoblastic Acute Leukemia) respectively located on chromosome 1 and 22. The t(1;22) translocation results in the fusion of these genes in all the cases studied to date. We summarize here present knowledge regarding this translocation.

Chromosomes, Human, Pair 1↗
PubMed1990

Childhood acute megakaryoblastic leukemia with internalization of hemic cells.

Two atypical cases of acute megakaryoblastic leukemia (AMKL) in infants diagnosed by immunophenotying are described. In both cases, the leukemic cells at diagnosis resembled monoblasts with reniform nuclei, fine reticular chromatin, and abundant grey-blue cytoplasm with pseudopods. In addition, these blasts frequently showed internalization of hemic cells. Therefore, the diagnosis of acute monocytic leukemia (AMOL) or malignant histiocytosis (MH) was initially suggested. However, alpha-naphthyl butyrate esterase stain was negative and immunologic studies determined megakaryocytic lineage of the blasts. Our observation in two consecutive cases of AMKL implies that there is a potential risk of misdiagnosing AMKL as AMOL or MH in infants. The incidence and significance of internalization of hemic cells by blast cells of AMKL in infancy are unknown and we cannot be certain whether these cases constitute a subgroup of AMKL in infancy.

Bone Marrow↗
PubMed2002

Skeletal manifestations of pediatric acute megakaryoblastic leukemia.

Once considered rare, acute megakaryoblastic leukemia (AMKL) now accounts for about 12% of all cases of de novo acute myeloid leukemia in children. Most cases of AMKL are difficult to diagnose because of their complex clinical presentation and unusual bone marrow morphologic features. In children, AMKL is often confused with metastatic solid tumors or myelodysplastic syndrome. Between January 1984 and December 1999, 43 patients were diagnosed with childhood AMKL at the authors' institution. Five of these presented with unusual skeletal lesions. These abnormalities (bilaterally symmetrical periostitis and osteolytic lesions) differed markedly from those commonly reported in association with pediatric acute leukemias. The authors present their experience and review the literature to define the spectrum of bony involvement associated with AMKL. This report will contribute to the evolving clinical characterization of this entity and increase clinicians' and radiologists' awareness of the manifestations of AMKL.

Bone and Bones↗
PubMed1994

Immunolocalization of platelet-derived growth factor, transforming growth factor-beta, and fibronectin in acute megakaryoblastic leukemia manifesting tumor formation.

Acute megakaryoblastic leukemia (AMKL) manifesting myelofibrosis and tumor formation in the liver with marked increase of reticulin is described. The megakaryoblastic nature of the leukemic cells of the bone marrow and the hepatic tumor nodule was established by positive immunohistochemical stains for CD41a and CD41b on frozen tissue sections. Immunolocalization of the platelet-derived growth factor (PDGF) protein and transforming growth factor (TGF)-beta protein also was demonstrated in the leukemic cells of the bone marrow and the hepatic tumor. Further, the deposition of fibronectin that has been known as the ligand of CD41a molecule and collagen types I and IV were recognized in the extracellular matrix of the bone marrow and the hepatic tumor. These results suggest that specific expression of growth factor proteins by the leukemic cells may selectively regulate the fibrosis of the bone marrow as well as the tumor formation of AMKL. The expression of adhesion molecules and growth factor proteins by the leukemic cells and the deposition of extracellular matrix are discussed in relation to the myelofibrosis as well as the tumor-forming nature of AMKL.

Collagen↗
PubMed2005

Acute panmyelosis with myelofibrosis: an entity distinct from acute megakaryoblastic leukemia.

The WHO criteria for diagnosing acute panmyelosis with myelofibrosis are somewhat distinct from those for acute megakaryoblastic leukemia. However, clinical and hematopathologic findings partially overlap. This has raised questions as to whether these are indeed separate, definable entities. To determine the potential importance of bone marrow biopsy supplemented by immunohistochemistry in distinguishing between these two conditions, we studied 17 bone marrow biopsies of well-characterized cases of acute panmyelosis with myelofibrosis (six cases) and acute megakaryoblastic leukemia (11 cases). We compared blast frequency, reticulin content, CD34 expression, and the degree of megakaryocytic differentiation of the blast cells in these two conditions. Our results demonstrate important differences. Acute panmyelosis with myelofibrosis is characterized by a multilineage myeloid proliferation with a less numerous population of blasts than acute megakaryoblastic leukemia (P<0.01). In the former condition, blasts are always positive with CD34, while in acute megakaryoblastic leukemia they express CD34 in 60% of the cases. The blasts in acute panmyelosis with myelofibrosis only rarely express megakaryocytic antigens. By contrast, acute megakaryoblastic leukemia has a significantly higher proportion of blasts expressing megakaryocytic antigens (P<0.01 with CD42b). Our results confirm that histology supplemented by immunohistochemistry permits the distinction of these conditions in routinely processed bone marrow biopsies.

Acute Disease↗