Characterization of blast cells in chronic granulocytic leukaemia in transformation, acute myelofibrosis and undifferentiated leukaemia. I. Ultrastructural morphology and cytochemistry

Minimally Differentiated Acute Myeloid Leukemia: A Morphologic, Cytochemical and Ultrastructural Study

Seven of 368 cases of acute myeloid leukemia (AML) could not be subclassified by routine morphologic, cytochemical and immunologic analyses during the period January 1989 to December 1990. Further investigations including ultrastructural examination, anti-myeloperoxidase and myeloid specific antigen analysis were carried out in all these patients and they were classified as AML-MO, as per the FAB criteria. Morphologically these blasts resembled ALL-L2/AML-M1. Cytochemlcally they were negative for Sudan black, myeloperoxidase, periodic acid-Schiff, and non-specific esterase. On initial immunophenotypic analysis, they could not be classified Into B, T or myeloid lineages. Further investigations revealed CD13 and CD33 positivity in 4 of 6 patients. Anti-myeloperoxidase was positive in 6 of 6 patients and ultrastructural examination revealed myeloperoxidase-positive blasts in 6 of 7 cases. Cytogenetic analysis done in one patient revealed 60 % abnormal metaphases. Six of 7 cases were treated with aggressive chemotherapy. One patient achieved complete remission but relapsed after 6 months, whereas others were resistant to treatment. Hence we conclude that an aggressive investigative and therapeutic approach is required to identify and treat AML-MO.

Morphologic, Immunologic, and Cytogenetic Characteristics of Secondary Acute Unclassifiable Leukemia in Hodgkin's Disease

Blast cells from five cases of secondary unclassifiable leukemia following therapy for Hodgkin's disease were studied by cytochemical, immunological and cytogenetic analyses. Cytochemical and immunological reactivity were in accordance with poorly differentiated, myeloid blasts. The four cases in which karyotype analysis was performed showed specific chromosomal abnormalities. No evidence of multiple lineage involvement was found. Problems in classifying these cases of secondary ANLL were due to the high grade of undifferentiation of the blast cells. Their low cytochemical reactivity with markers of myeloid differentiation was similar to what may be observed in patients with acute undifferentiated leukemia or with chronic myeloid leukemia in blast crisis.

Myeloperoxidase cytochemical negativity: an unexpected but intrinsic property of blasts of all phases of chronic myeloid leukemia

Myeloperoxidase (MPO) cytochemical activity, recognized as a very important hallmark of myeloblasts, is generally negative in chronic myeloid leukemia (CML) blast crisis (BC). Because this finding is unexpected, being not in keeping with the myeloproliferative nature of CML, we tried to ascertain if MPO cytochemical negativity could be an intrinsic property of blasts of CML and hence present in the preblastic phases as well. Myeloperoxidase cytochemistry of peripheral blood blasts in 161 cases of CML, including 103 in chronic phase (CP) and 29 each in accelerated phase (AP) and BC, was assessed and compared with that of 30 cases of acute myeloid leukemia, AML-M2. Blasts of 97 (94.2%) of 103 cases of CP, 28 (96.6%) of 29 cases of AP, and 22 (75.9%) of 29 cases of BC were negative for MPO (<3% MPO-positive blasts). Compared with the strong MPO positivity, both in terms of intensity and proportion, in the AML-M2 cases, the positivity in the CML cases was generally weak and was seen in a small number of blasts (5-15%), except in one case of BC with 20% positive blasts. Absence or, at times, weak MPO cytochemical activity is an intrinsic property of blasts of all phases of CML, and use of the term myeloblast in CML should be understood to refer to a cell with this property. This also explains why MPO cytochemistry, despite its high reputation as a myeloid-lineage marker, generally does not help in CML BC. CML BC should therefore be considered as a possible diagnosis along with acute lymphoblastic leukemia, AML-M0, AML-M7, etc., in the setting of MPO-negative blasts. Similarity between MPO expression pattern in CML, i.e., negative in blasts and positive in the more mature cells, and that during maturation of normal myeloid series of cells shows the deranged myelopoiesis of CML to be undisturbed at least with respect to MPO expression. There is need for a more comprehensive study of blasts of preblastic phases.

Excessive apoptosis, increased phagocytosis, nuclear inclusion bodies and cylindrical confronting cisternae in bone marrow biopsies of myelodysplastic syndrome patients

Transmission electron microscopic (TEM) studies have not been reported in bone marrow (BM) biopsies of patients with myelodysplastic syndromes (MDS) owing to failure to overcome the technical impediment of maintaining ultrastructural detail in decalcified tissue. Using a modified technique to physically separate pieces of bone from marrow tissue under a dissecting microscope, and embedding the material directly for TEM, ultrastructural studies were performed in 15 MDS patients and four normal BM biopsies. Biopsy tissue was also used to initiate long-term in vitro cultures and 12-week plates were sacrificed for TEM analysis. Features noted in freshly obtained decorticated tissue included an excessive apoptosis in both haematopoietic and stromal cells, ringed sideroblasts with iron-laden mitochondria and highly active, enormously increased phagocytosis. In addition, type IV nuclear inclusion body variants (NIB-v) and confronting cylindrical cisternae (CCC) were readily identified in up to 40% of stromal cells in vivo, providing an important footprint of a possible infectious agent in the pathology of MDS. Cultured stromal cells did not show excessive apoptosis and only 2-4% fibroblasts showed the presence of NIB-v or CCC, underscoring the artificial nature of ex vivo systems. We conclude that ultrastructure studies using decorticated tissue can be a powerful tool to investigate the biology and aetiology of a variety of haematopoietic disorders as it enables the direct examination of BM biopsies with their intimate stromal parenchymal cell associations preserved intact.

Intramedullary apoptosis of hematopoietic cells in myelodysplastic syndrome patients can be massive: apoptotic cells recovered from high-density fraction of bone marrow aspirates

A higher percentage of apoptotic cells (apoptotic index or AI) is consistently found in bone marrow (BM) biopsies compared to BM aspirates of patients with myelodysplastic syndrome (MDS). Most studies have only investigated the low-density fraction (LDF) mononuclear cells from BM aspirates following density separation for AI determination. In the present study, both LDF and high-density fraction (HDF) cells for AI were examined by electron microscopy (EM) in 10 MDS patients and 4 healthy donors. Matched BM biopsies were subjected to AI detection by in situ end labeling (ISEL) of fragmented DNA. The results indicate that in LDF and HDF cells, AI is consistently higher in MDS patients (8.5% vs 1.5%, respectively; P = .039) compared to healthy donors (27% vs 4%, respectively; P = .004). The BM biopsy AI was also higher in MDS patients than in healthy donors (3+ vs 0+, respectively; P = .036). In addition, in MDS patients, more apoptotic cells were found in HDF cells than in LDF cells (27% vs 8.5%, respectively;P = .0001). All stages of maturation, ranging from blasts to terminally mature cells belonging to all 3 lineages, were represented in the dying cells in both compartments. Using EM, typical Pelger-Huett–type cells appeared to be apoptotic granulocytes. Both LDF and HDF cells should be examined for an accurate estimation of apoptotic cells because AI would be underestimated if only the LDF cells were studied. Ultrastructural studies consistently show a higher AI in BM biopsies compared to BM aspirates despite the correction factor of HDF cells provided by AI. This may represent the actual extant state, which could conceivably be due to a higher concentration of proapoptotic signals in the biopsies.

Intramedullary apoptosis of hematopoietic cells in myelodysplastic syndrome patients can be massive: apoptotic cells recovered from high-density fraction of bone marrow aspirates

A higher percentage of apoptotic cells (apoptotic index or AI) is consistently found in bone marrow (BM) biopsies compared to BM aspirates of patients with myelodysplastic syndrome (MDS). Most studies have only investigated the low-density fraction (LDF) mononuclear cells from BM aspirates following density separation for AI determination. In the present study, both LDF and high-density fraction (HDF) cells for AI were examined by electron microscopy (EM) in 10 MDS patients and 4 healthy donors. Matched BM biopsies were subjected to AI detection by in situ end labeling (ISEL) of fragmented DNA. The results indicate that in LDF and HDF cells, AI is consistently higher in MDS patients (8.5% vs 1.5%, respectively; P = .039) compared to healthy donors (27% vs 4%, respectively; P = .004). The BM biopsy AI was also higher in MDS patients than in healthy donors (3+ vs 0+, respectively; P = .036). In addition, in MDS patients, more apoptotic cells were found in HDF cells than in LDF cells (27% vs 8.5%, respectively;P = .0001). All stages of maturation, ranging from blasts to terminally mature cells belonging to all 3 lineages, were represented in the dying cells in both compartments. Using EM, typical Pelger-Huett–type cells appeared to be apoptotic granulocytes. Both LDF and HDF cells should be examined for an accurate estimation of apoptotic cells because AI would be underestimated if only the LDF cells were studied. Ultrastructural studies consistently show a higher AI in BM biopsies compared to BM aspirates despite the correction factor of HDF cells provided by AI. This may represent the actual extant state, which could conceivably be due to a higher concentration of proapoptotic signals in the biopsies.

AML-M0: a review of laboratory features and proposal of new diagnostic criteria

In 1991, the FAB group published a proposal to designate acute leukemias with minimal signs of myeloid differentiation as AML-M0. This proposal was meant to offer a provisional basis for the study of immature myeloid forms, with the understanding that it was susceptible to changes and improvements with new information derived from the laboratory. Since then there have been a number of reports detailing the biological and clinical features of patients with AML-M0. In this article we review the laboratory data acquired from various sources and suggest a partial modification of diagnostic criteria.

Diagnosis of acute basophilic leukemia

De novo acute basophilic leukemia (ABL) is a rare form of acute leukemia. Most frequently, the blast cells are morphologically undifferentiated, and the recognition of the presence of coarse basophilic granules may be the first step in diagnosis of this rare disorder. These granules are metachromatic and MPO negative. Immunophenotyping shows myeloid markers and some more specifically associated antigens such as CD9 or CD25 which are strongly expressed. Lymphoid, erythroid or megakaryocytic markers are not significantly expressed. In the absence of basophilic granules, some cases are classified as AML M0 if they express myeloid markers, or undifferentiated leukemia if no markers are present. If specific immature basophilic or theta granules are present, only an electron microscopic study will enable the diagnosis of a basophilic lineage assignment. Some cases may be misdiagnosed if all these steps are not followed. After all these investigations, two types of ABL may be defined: 1-A pure ABL, monophenotypic with basophilic lineage involvement alone, which should be classified as AML M8 . Genetic studies in these cases are very important for understanding the leukemic process and in a few cases, we can suspect c-MYB oncogene involvement but further investigations are still necessary. 2- More frequently, acute leukemia can be a mixture of blasts from different lineages with an important but variable participation of mature or immature basophilic cells. These cases must be classified as AML/Baso or multiphenotypic acute leukemias and often present Phl -chromosomal abnormality.

Expression of erythroid-specific genes in megakaryoblastic disorders

Currently available data indicate that erythroid and megakaryocytic differentiation pathways are closely related to each other, and there may exist progenitor cells common to those two lineages may exist. Acute megakaryoblastic leukemia (AML-M7) and transient myeloproliferative disorder in Down's syndrome (TMD) are characterized by rapid growth of abnormal blast cells which express megakaryocytic markers. These blast cells express lineage-specific transcription factors such as GATA-1 common to these lineages and frequently express erythroid-specific mRNAs such as gamma-globin and erythroid delta-aminolevulinate synthase (ALAS-E), indicating that most of the blasts in M7 and TMD cases have erythroid and megakaryocytic phenotypes. These results suggest that blasts in M7 and TMD may correspond to progenitors of both erythroid and megakaryocytic lineages.

Contribution of immunophenotypic and genotypic analyses to the diagnosis of acute leukemia

Diagnostic accuracy in acute leukemia (AL) can be improved if traditional morphology and cytochemistry are supplemented with immunophenotypic and genotypic analyses. This multiparameter approach is of crucial importance for the management of patients, as it enables the identification of leukemic syndromes with distinct biological features and response to treatment. Immunophenotyping using monoclonal antibodies has been universally accepted as a useful adjunct to morphological criteria. This technique is particularly valuable in diagnosing and subclassifying acute lymphoblastic leukemia and is also essential in certain types of acute myeloid leukemia (AML), such as AML with minimal differentiation or acute megakaryoblastic leukemia. Cytogenetic findings can be quite helpful in establishing the correct diagnosis and can add information of prognostic significance. A number of specific chromosomal abnormalities have been recognized that are very closely, and sometimes uniquely, associated with morphologically and clinically distinct subsets of leukemia. An even more basic understanding of normal and malignant hematopoietic cells has begun to evolve as molecular biology begins to unravel gene misprogramming by Southern and Northern blot analysis, the polymerase chain reaction, and fluorescence in situ hybridization. With the extensive use of these techniques it has become apparent that a proportion of leukemias exhibit the biologically relevant molecular defect in the absence of a karyotypic equivalent. On the other hand, apparently uniform chromosomal abnormalities such as the t(1;19) (q23;p13), t(9;22) (q33;q11), t(8;14) (q24;q32), or t(15;17) (q21;q21) may differ at the molecular level. Data collected from these modern technologies have introduced a greater complexity, which needs to be taken into consideration to improve both the diagnostic precision and the reproducibility of current classifications.

Immunological and ultrastructural studies in acute biphenotypic leukaemia

AIMS

To compare the sensitivity of the ultrastructural method to detect myeloperoxidase (MPO) with light microscopy and immunocytochemistry using an anti-MPO antibody; to examine the expression of lymphoid antigens in relation to MPO activity in blast cells from cases of biphenotypic leukaemia.

METHODS

Blast cells from 14 cases of biphenotypic acute leukaemia were analysed. Immunological markers were performed by single or double immunofluorescence staining on a flow cytometer. The presence of MPO was determined by light microscopy, electron microscopy on fixed and unfixed cells, and by immunoalkaline phosphatase with an anti-MPO antibody. The immunogold method was applied at the ultrastructural level to assess the expression of lymphoid and myeloid antigens at the same time as the MPO activity.

RESULTS

Six of the 14 cases were initially classified as acute lymphoblastic leukaemia (ALL) and eight as acute myeloid leukaemia (AML). MPO activity was shown at the ultrastructural level in 4-99% blasts from all cases. Six of the 14 were MPO negative by light microscopy and three of these were negative with the antibody anti-MPO. Coexpression of lymphoid antigens (CD19, CD10, or CD2) and MPO was shown by the immunogold method in four out of 11 cases; in seven cases the blasts coexpressed myeloid antigens (CD13, CD33) and MPO.

CONCLUSIONS

Electron microscopy is more sensitive for showing MPO than light microscopy and immunocytochemistry; the immunogold method combined with MPO used at the ultrastructural level can help to define the cell lineage involved in biphenotypic leukaemia by highlighting the myeloid component defined by MPO.

Megakaryocyte markers in myeloproliferative disorders

Identification of megakaryocyte precursors with immunohistochemical methods in bone marrow trephine biopsy specimens (embedded in a plastic resin, Immuno-Bed) was performed from patients with blastic phase of chronic granulocytic leukaemia (five cases), from chronic megakaryocytic-granulocytic myelosis (four cases) and from acute megakaryoblastic leukaemia (11 cases). In megakaryoblasts of bone marrow biopsies immunohistochemical reactions using the ABC method and monoclonal antibodies against von Willebrand antigen and GpIIb/IIIa (CD41) were visible in various percentages depending on the maturation's degree of megakaryocyte precursors. The number of circulating blast cells determined by flow cytophotometry was nearly similar to those of observed in biopsies. The greatest bone marrow reticulin content could be detected in acute megakaryoblastic leukaemia cases. Despite the different clinicopathological entities, the presence of the same phenotype (megakaryoblasts) was associated with a short survival in these haematological malignancies (in CGL MKB phase 4.0, in CMGM MKB phase 4.2, and in AML M7 5.8 months, respectively).

Transient abnormal myelopoiesis in Down's syndrome

Recent data have elucidated the pathogenesis of transient abnormal myelopoiesis (TAM) to a great extent. TAM is a monoclonal disorder which resolves spontaneously and the target cell in this disorder is a multipotent stem cell which is capable of differentiating into megakaryocytes. The pathogeneses of TAM/AMKL (acute megakaryoblastic leukemia) appears to be closely associated with abnormal quality and quantity of a gene located on chromosome 21. AMKL developing after the regression of TAM appears to come from the same clone as the TAM, which apparently experiences some kind of genetic alterations. It seems that the gene responsible for TAM will soon be cloned in the near future. However, the mechanism of spontaneous regression of TAM has as yet not been clarified. The expanding clone in the transient physiological immunodeficient state, during the perinatal period, might be eliminated with the maturation of more mature immunosurveillance. Alternatively, the TAM clone might be destined to undergo spontaneous death, which is called "programmed cell death" (apoptosis). The mechanism of this phenomenon awaits further elucidation.

Ultrastructural and ultracytochemical differences between megakaryoblastic leukemia in children and adults. Analysis of 49 patients

BACKGROUND

Acute megakaryoblastic leukemia (AMKL) has two peaks in distribution of incidence (in adults and children 1 to 2 years of age) and is frequently seen in children with Down syndrome. The current study was undertaken to disclose whether there were any differences between these groups.

METHODS

Electron microscopic and ultrastructural cytochemical features of 49 children and adults with a AMKL or chronic myelogenous leukemia (CML) in megakaryoblastic crisis were compared.

RESULTS

Blast cells from children with AMKL, including those with and without Down syndrome, had immature features lacking typical alpha granules and a demarcation membrane system (DMS). However, blast cells from patients with AMKL with Down syndrome had more theta, electron-lucent, and basophil-like granules, suggesting that the blast cells had more potential to differentiate into other cell lines than megakaryocytes. The AMKL blast cells of adult patients showed a higher percentage of platelet peroxidase (PPO) positivity than other subgroups, and they occasionally contained typical alpha granules and DMS. This indicated that the blast cells of adults with AMKL were more mature than those of children and CML in megakaryoblastic crisis.

CONCLUSIONS

By electron microscopic analysis, leukemic megakaryoblasts differed between children with AMKL with and without Down syndrome, adults with AMKL, and patients with CML in megakaryoblastic crisis.

Abnormal granulopoiesis of leukemic cells with basophil/mast cell features. Cytochemical and ultrastructural observations

We have carried out cytochemical and ultrastructural examination of human leukemic cells showing basophil/mast cell features derived from patients with acute myelogenous leukemia or basophilic crisis in chronic myelogenous leukemia. Leukemic cells in each case initially showed metachromasia with toluidine blue and various degrees of positivity for astra blue. Other cytochemical results showed considerable variety among cases. The number of granules increased in short-term culture in every case. Ultrastructurally, small membrane-bound granules with or without myelinoid bodies or glycogen particles were present in immature blasts, followed by production of other granule types. In some cases, leukemic cells before and after liquid culture contained the typical basophil granules with or without myelinoid bodies, but the matrix was more loose than normal. Granules showing whorl or scroll matrix profiles, which were typical for mast cells, were present in two cases. In one case, immature leukemic cells contained theta granules, and some mature forms after short-term culture contained typical basophil/mast cell granules as well as theta granules. Leukemic cells occasionally contained multivesicular granules predominantly. These results indicate that leukemic cells with basophil/mast cell features show a heterogeneous configuration and contain abnormal granules differing from normal ones. This abnormal granulopoiesis may be attributable to the results of leukemic events and may be a hallmark for recognition of leukemic basophils/mast cells.

Comparative electron microscopy of basophils and mast cells, in vivo and in vitro

We compared the fine structure and electron microscopic cytochemical findings of basophils and mast cells from humans, guinea pigs, rabbits, mice and rats. The particulate structure was the most frequently observed and most typical structure of human and rabbit basophil granules and of guinea pig mast cell granules. The most prominent feature of guinea pig basophils and murine mast cells was that the fine structure of the granules was homogeneous. The fine structure of the granules in guinea pig basophils resembled that in murine mast cells, while the fine structure of the granules of guinea pig mast cells resembled those in human and rabbit mast cells. In mouse mast cells in culture, the majority of the granules contained small vesicles, which were also observed in human basophils in culture and in mouse basophils in vivo. The degrees of cytochemical reactivity of acid mucopolysaccharides among the species were different. Peroxidase activity was positive in most basophils and in human mast cells. Among mammals, the granules of basophils and mast cells present heterogeneous fine structure. It is of interest that the basophil granules of some species resemble the mast cell granules rather than the basophil granules of other species.

Heterogeneity of Leukemic Cells with Basophilic Features: Cytochemical, Ultrastructural and Immunophonotypic Analysis of 8 Cases

We have studied leukemic cells, derived from acute nonlymphocytic leukemia with basophilic features and basophilic crisis of chronic myelogenous leukemia (CML), by cytochemical and ultrastructural examination and analysis of surface markers. Cytochemical results varied from case to case, while the ultrastructural appearances of the granules were different from normal granules. The granules had more delicate granular matrices with or without myelinoid figures, whorled or scroll matrix, multivesicular bodies structures, theta granules, and crystalloid structures. Leukemic cells in all cases had myeloid surface markers with some degree of variability. In addition, they were occasionally positive for lymphoid markers, but not for CD10 and IgE receptors. The present results show that leukemic cells with basophilic features are heterogeneous in their morphology, cytochemistry and surface markers.

Blood findings in generalized mastocytosis: evidence of frequent simultaneous occurrence of myeloproliferative disorders

Blood findings in 61 cases of generalized mastocytosis (GM) were evaluated. The cases were divided into two major variants: Systemic mastocytosis (SM; n = 34) with urticaria pigmentosa-like skin lesions, and malignant mastocytosis (MM; n = 27), without skin involvement. The following results were obtained: (1) Significant differences between MM and SM were found in the main haematological parameters (erythrocyte, platelet and leucocyte counts and haemoglobin level); normal values were found in 16 of the SM cases, but never in MM. (2) The main pathological findings were: in SM, anaemia (9/34) and leucocytosis (5/34); and in MM, leucocytosis (19/27), monocytosis (14/27), eosinophilia (12/27), bicytopenia (12/27, mostly anaemia with thrombocytopenia), basophilia (10/27) and isolated anaemia (7/27). (3) The major finding was a significant difference between MM and SM in the incidence of myeloproliferative disorders (MPD), myelodysplasia and mast cell leukaemia (MCL): these disorders occurred in 23 (92%) MM patients, but only in two (6%) SM patients (P less than 0.001). The four instances of MCL and two of myelodysplasia all occurred with MM. Of the 19 cases of MPD, six (SM, 1; MM, 5) were acute variants (acute myeloid and myelomonocytic leukaemias) and 13 (SM, 1; MM, 12) were chronic variants. No case of malignant lymphoma was noted. (4) The blood picture in 10 of 13 chronic MPD cases represented an atypical chronic myeloid leukaemia for which the preliminary descriptive term 'mastocytosis-associated MPD' is proposed. (5) A survey of 103 published cases (SM, 77; MM, 26) yielded similar findings, including a high incidence of MPD and MCL in MM. These findings add further weight to the argument for recognizing SM and MM as two separate entities.

Aggressive polychemotherapy for acute myelofibrosis

Acute myelofibrosis is a rare and still ill-defined disease. Based on morphological observation, immunophenotyping and ultrastructural analysis, we support the assumption that acute myelofibrosis is a malignant disorder mainly of the megakaryocytic lineage and is closely related to acute megakaryocytic/blastic leukaemia. Consequently, the 11 patients reported here were treated with aggressive polychemotherapy with combinations including daunorubicin and cytosine arabinoside and 6-thioguanin or VP16-213. 4 complete remissions, 2 partial remissions and 1 minor response were observed. Duration of aplasia was not significantly prolonged. These findings indicate that the use of aggressive polychemotherapy is feasible in acute myelofibrosis and results in a significant number of remissions.

Cytogenetic findings in adult acute leukemia and myeloproliferative disorders with an involvement of megakaryocyte lineage

Cytogenetic analyses were performed on 12 adult patients with abnormal megakaryoblastic proliferation which was detected by ultrastructural cytochemical study (platelet peroxidase) and platelet-megakaryocytes-specific monoclonal antibodies (TP-80, Plt1, AN51, and KOR-77). The patients consisted of two patients with myelodysplastic syndromes (MDS), three with acute megakaryoblastic leukemia (AMKL), six with megakaryoblastic transformation in Philadelphia-positive chronic myelogenous leukemia (CML-meg-BC), and one case of chronic myeloproliferative disorder (CMPD). Among them, an inversion of the long arm of chromosome 3 [inv(3)(q21q26)] was found in one AMKL patient with a normal platelet count. Chromosome change at band 3q26 was also found in one MDS patient without thrombocythemia. Furthermore, the long arm of chromosome 13, where rearrangements in myelofibrosis are clustered (13q12----q22) was seen in one MDS patient. Trisomoy of chromosome 19 was found in one AMKL patient and three CML-meg-BC patients. These findings indicate that cytogenetic abnormalities involving 3q26, 13q, and trisomy 19 are associated with hematologic neoplasia with megakaryocytic lineage in adult patients, although these abnormalities were not related to the survival of the patients. During the period of this study, two acute myelogenous leukemia patients (AML-M2 and AML-M5b) with chromosome rearrangements at band 3q21 and thrombocythemia were found, indicating that chromosome abnormality at band 3q21 is related to quantitative platelet dysfunction, whereas that at 3q26 is related to hematologic malignancies with a proliferation of megakaryocytic lineage.

An immunomorphometric study on megakaryocyte precursor cells in bone marrow tissue from patients with chronic myeloid leukemia (CML)

An immunomorphometric study was performed on trephine biopsies of the bone marrow in 41 patients with chronic myeloid leukemia (CML) to determine number and size of megakaryocytic precursor cells (pro- and megakaryoblasts). For specific staining, a monoclonal antibody against platelet glycoprotein IIIa (Y2/51) was employed which is applicable on routinely fixed and paraffin embedded tissue. In comparison with control specimens from 15 patients, in CML morphometric analysis revealed an increase in the total amount of megakaryocytes per square and cubic millimeter marrow tissue, but particularly in patients with thrombocythemia. Moreover, a non-disorderly expansion of the megakaryocyte precursor pool was recognizable by showing a relative frequency of pro- and megakaryoblasts in congruence with the normal value. In this context a significant correlation between the counts for Y2/51-positive megakaryocytic elements and promegakaryoblasts with the corresponding platelet values was encountered. The more mature stages of megakaryopoiesis (pro- end megakaryocytes) disclosed a relevant shift to smaller cell forms with rounded cell perimeters and a more compact aspect of their nuclei. Additionally, in 6 patients with CML, evolution into a subacute and manifest (micro)-megakaryoblastic transformation accompanied by myelofibrosis could be demonstrated by a retrospective review of file material.

Philadelphia chromosome-negative acute hematopoietic malignancy: ultrastructural, cytochemical and immunocytochemical evidence of mast cell and basophil differentiation

We describe a patient with fever and multiple osteolytic bone lesions accompanied by hypercalcemia, a duodenal ulcer, anemia, and thrombocytopenia. Bone marrow showed a dense infiltration by abnormal cells characterized by small basophil granula, erythrophagocytosis and nuclear atypia. These cells were positive for toluidine blue and partly for myeloperoxidase and chloroacetate esterase, expressed myeloid differentiation markers, and exhibited multiple numerical and structural chromosome aberrations. Molecular genetic analysis showed no breakpoint cluster region rearrangement. Electron microscopy demonstrated granula both of basophil and mast cell type. Concluding, in this patient an acute hematopoietic malignancy with many features of malignant mastocytosis but also with signs of a basophil differentiation. This is further support for a hematopoietic stem cell origin of human mast cells.

Biological and clinical features of acute lymphoblastic leukaemia with cytoplasmic granules or inclusions: description of eight cases

We describe eight patients (four children and four adults) with an acute lymphoblastic leukaemia (ALL) with cytoplasmic granules or inclusions. The incidence of this variant of acute leukaemia in our whole series of patients with ALL is 1.8%. The granules or inclusions were usually positive for aspecific esterases (ANAE) and/or acid phosphatase, and the immunophenotype was in all cases typical of a CALLA positive B-lineage ALL (CD10+, CD19+ and/or CD24+, DR+, TdT+, anti-T-, anti-My-, SIg-). In one paediatric case, CD33 was unusually coexpressed. Ultrastructural investigations were performed in one case and demonstrated large granules containing vesicles, usually membrane bound, in the majority of blast cells. In the two cases analysed, Ig heavy chain gene rearrangement was detected. In this series of patients prognosis was poor since three never achieved a complete remission, four relapsed and only one is still in first continuous remission.

Acute nonlymphocytic leukemia with basophilic differentiation and t(9,11)(p22,q23) in a child

A 20-month-old child was treated for acute nonlymphocytic leukemia (ANLL) with basophilic differentiation. His leukemic cells also had the cytogenetic abnormality of t(9,11)(p22,q23). Although immature blasts responded well to induction therapy with etoposide, the leukemic cells that were more differentiated toward basophils were quite refractory to the drug. However, complete remission was finally achieved with a conventional multidrug regimen.

Leukaemoid reaction with megakaryocytic features in newborns with Down's syndrome

A leukaemoid reaction was observed in 3 newborns with Down's syndrome. Thrombocytopenia was present in 2, requiring platelets transfusions in 1, and red cell transfusions were necessary in 2 patients. Blast cells characterization by specific monoclonal antibodies showed a prevalence of megakaryoblasts in all 3 cases. This feature was confirmed in 2 of them by the demonstration of platelet peroxidase (PPO) activity under transmission electron microscopy (TEM). A spontaneous remission of the leukaemoid picture was observed after 2-3 months. However, in 1 case a relapse of the myeloproliferative disorder with the same features of the blast cell population was diagnosed after 16 months. Chemotherapy with low-dose Ara-C, started because of a relevant clinical involvement, induced a complete remission.

Platelet peroxidase-positive blast cells in transient myeloproliferative disorder with Down's syndrome

Transient myeloproliferative disorder accompanied by Down's syndrome has been characterized as exhibiting self-limiting haematological abnormalities. We studied six patients suffering from this disorder in order to clarify the biological nature of their blast cells. Metaphases of leucocytes stimulated with phytohaemagglutinin (PHA) showed trisomy 21 in all patients except one. The exception was constitutionally trisomy 21 mosaic (46,XY = 89/47,XY,+21 = 11). However, metaphases from the peripheral blood cells (blast cells: 70%) without PHA stimulation showed exclusively trisomy 21. Simultaneous examination for morphology and chromosomal analysis on single colonies revealed that granulocyte-macrophage (GM) colonies and an erythroid colony contained only cells with the trisomy 21 karyotype. The blast cells showed positive reactions for platelet peroxidase (PPO) and with monoclonal antibodies against platelet-megakaryocyte antigen (TP 80 and TP 82). In methylcellulose and liquid culture systems, high plating efficiencies were observed, and mainly mature basophils containing histamine developed in the presence of PHA-stimulated leucocyte conditioned medium (PHA-LCM). In vivo, mature neutrophils, basophils, eosinophils or megakaryocytes coexisted with PPO-positive blast cells in the peripheral blood of some patients with this disorder. These findings suggest that transient myeloproliferative disorder is characterized by a proliferation of PPO-positive blast cells with trisomy 21, although some heterogeneity may be seen.

Prognostic implications of basophil differentiation in chronic myeloid leukemia

Basophilia has been reported to indicate an accelerated phase of chronic myeloid leukemia (CML), heralding a poor prognosis. We have studied 47 patients with chronic-phase CML by basophil growth and differentiation assays in vitro, demonstrating an association between basophil growth index (BGI) and clinical time to blast crisis as well as overall survival. In addition to confirming an association between positive BGI and phase of CML in a larger group of patients, a positive BGI predicted death or blast crisis within 2 years' study of chronic phase CML (p less than 0.01), with a sensitivity of 78%, specificity, 81%; the positive predictive value of a positive test, 64%; and a negative predictive value of a negative test, 89%. The survival experience of the 22 evaluable patients with chronic-phase CML and a positive BGI was significantly worse than the survival of the 19 patients with a negative BGI (p less than 0.0001). At 1, 2, and 3 years the proportion of surviving patients with a positive BGI was 0.64, 0.32, and 0.23, respectively, compared with 1.00, 0.90, and 0.79 for those with a negative BGI. The median survival of chronic phase CML patients with a positive test at diagnosis (n = 14) was 27 months versus 54 months for those with a negative diagnosis (n = 14) (p less than 0.05). These findings emphasize the prognostic utility of basophil growth assays in CML and suggest a molecular relationship between leukemic transformation and basophil lineage expression.

Establishment of an immature mast cell line from a patient with mast cell leukemia

A cell line showing many characteristics of immature mast cells has been established from the peripheral blood of a patient with mast cell leukemia. Cultured cells contain low levels of histamine, are stained metachromatically by toluidine blue, and contain chloroacetate esterase, aminocaproate esterase and tryptase activities. The cells lack T and B lymphocyte, as well as myeloid cell markers, and do not possess IgE receptors. Solid tumors of metachromatically positive cells have been successfully induced and serially passed in nude mice using 5-azacytidine transformed cells. This cell line may be useful for future studies of mast cells and their constituents.

Immunophenotype of blast cells in chronic myeloid leukemia

The immunophenotype of peripheral blood blast cells from 14 patients in the chronic phase of chronic myeloid leukemia (CML) was studied using a panel of monoclonal antibodies (McAb) directed against megakaryocytic, granulomonocytic, erythroid and lymphoid antigenic determinants. The blast cells were enriched by a simple bovine serum albumin (BSA) density-cut separation and cooled in liquid nitrogen. The study was done using the alkaline phosphatase-anti-alkaline phosphatase (APAAP) technique on the thawed blast cells. A consistent pattern of reactivity with McAb was found in all patients, showing that blast cells were heterogeneous. A minor component of the blast cells react with platelet antibodies, most of them being labelled with anti-GPIIb-IIIa McAb. Anti-GPIb and Von Willebrand factor McAb detected 4 times fewer megakaryocytic blast cells, suggesting that these cells are located very early in the differentiation scheme. Two major blast cell compartments were labelled with early myelomonocytic (anti-CD13: MY7) and early erythroid (anti-CD36: FA6-152) McAb. The CD34 (My10) and DR antigens which are expressed by immature blast cells and myeloid progenitors of human bone marrow (BM) were present on more than 50% of the CML blast cells. Thus, the blast cells of chronic phase CML patients, showed the same cellular diversity as the increased progenitor cell compartment observed in this disease, and their differentiation stages seemed to be very closely related.

Chronic myelogenous leukemia in blast crisis. Analysis of 242 patients

Two hundred forty-two patients with Philadelphia chromosome-positive chronic myelogenous leukemia in blast crisis were reviewed to identify significant biologic and prognostic associations. Twenty percent of patients had lymphoid blast crisis. Clonal evolution was present in 60 percent of patients at blast crisis and involved most frequently the development of a double Philadelphia chromosome, trisomy 8, or isochromosome 17. The overall median survival from blast crisis was 18 weeks. Patient characteristics demonstrated to have significant association with short survival were: anemia; thrombocytopenia; myeloid or undifferentiated blast cell morphology; clonal evolution involving the presence of a double Philadelphia chromosome, trisomy 8, or isochromosome 17; and low marrow blast percentage. Of 195 patients who received therapy for blast crisis, complete remission was achieved in 44 (23 percent) patients, and 24 (13 percent) patients had a partial remission or hematologic improvement. Lower complete remission rates were associated with old age, thrombocytopenia, myeloid or undifferentiated blast cell morphology, clonal evolution--especially isochromosome 17 and trisomy 8--and long interval from diagnosis to onset of blast crisis. A multivariate analysis identified two characteristics to have independent prognostic importance for both survival and remission: platelet counts and blast cell morphology. In addition, clonal evolution had additive prognostic value for survival (double Philadelphia chromosome) and for response (isochromosome 17). The beneficial association of therapy with survival was demonstrated by the significantly longer median survival of patients treated since 1981 compared with those treated earlier, even after accounting for the pretreatment prognostic factors, and by the significant improvement in survival of patients achieving remission using the "landmark" analysis technique.

Megakaryoblastic transformation of chronic granulocytic leukemia

Three cases of megakaryoblastic transformation of chronic granulocytic leukemia (CGL) are reported. In each case, the leukemic transformation had morphologic features suggesting megakaryocytic differentiation. This was confirmed by positive immunostaining with a monoclonal antibody (HP1-1D) specific for platelet and megakaryocyte glycoprotein IIb/IIIa antigen, which was expressed by the majority of the leukemic blasts in all three cases. Cases with evidence of multilineage differentiation of the leukemic transformation were excluded. A striking feature in two patients was the manifestation of lytic bone lesions and soft tissue masses at presentation. A biopsy of a lytic bone lesion and soft tissue mass in one patient revealed a megakaryoblastic leukemic infiltrate, which by immunocytochemical staining was positive for the megakaryocytic markers, glycoprotein IIb/IIIa antigen, and Factor VIII (von Willebrand factor) antigen. In contrast to granulocytic sarcomas, the megakaryoblastic sarcoma did not stain cytochemically for chloroacetate esterase. The mean survival after acute transformation was 5.3 months. The three cases of megakaryoblastic transformation represented a significant proportion of all CGL blastic transformation cases (ten cases) evaluated by bone marrow examination in our institution during a 13-month period. Megakaryoblastic transformation of CGL may occur more frequently than has been appreciated, and can present as lytic bone lesions or as soft tissue megakaryoblastic sarcomas.

Cytochemical profile of megakaryoblastic leukaemia: a study with cytochemical methods, monoclonal antibodies, and ultrastructural cytochemistry

A cytochemical study using: Sudan black B; alpha-naphthyl acetate (ANAE) staining; estimation of alpha-naphthyl butyrate (ANBE) esterase activity; acid phosphatase activity; and 5' nucleotidase activity was carried out in 15 cases of megakaryoblastic leukaemia. These included cases of M7 acute myeloid leukaemia and blast crises of chronic granulocytic leukaemia. The megakaryoblastic nature of the blasts was first established using two monoclonal antibodies against platelet glycoproteins, and by estimating the platelet/peroxidase reaction at ultrastructural level. Our findings suggest that megakaryoblasts have a typical cytochemical profile comprising positive ANAE staining and acid phosphatase activity with a predominant localisation in the Golgi zone and negative or weak ANBE activity. A similar positive cytochemical pattern was also found in five cases of erythroleukaemia (M6). The specificity of the 5'nucleotidase activity for megakaryoblasts was not confirmed. In most cases of megakaryoblastic leukaemia there was no 5'nucleotidase activity only two cases showed positive reactions--reactions were positive in several cases of myeloblastic and lymphoblastic leukaemia. We suggest that cytochemical methods may be useful in diagnosing M6 and M7 acute leukaemia because less than 40% of leukaemic cells react with specific monoclonal antibodies.

Characterization of the blast cell population in two neonates with Down's syndrome and transient myeloproliferative disorder

The phenotype and in vitro growth properties of blood and marrow blast cells detected in two neonates with Down's syndrome and a transient leukaemic picture are presented. In both patients, blast cells at diagnosis were heterogeneous and expressed predominantly megakaryocyte and erythroid markers identified by membrane fluorescence using monoclonal antibodies or ultrastructural detection of platelet peroxidase and ferritin. An additional trisomy involving chromosome 22 was detected in blast cells from one patient. Blood and marrow cells colony-assays performed at diagnosis revealed precursors with an abnormal differentiation capacity similar to those found in acute myelogenous leukaemia colony assays. However, an unusual feature was the persistence of high numbers of precursor cells (namely erythroid) following a normal differentiation pathway. Phenotypically and cytogenetically abnormal cells spontaneously disappeared by week 4-6, but overt relapse occurred in one patient 20 months later. These results bring strong arguments in favour of the neoplastic nature of the transient leukaemic picture observed in some neonates with Down's syndrome. Furthermore, we suggest that this disorder can be individualized as a separate entity with specific phenotypic and biological properties.

'Pseudo-lymphoid' leukaemia with unusual features: ultrastructural, immunological, cytogenetic and molecular studies

An unusual case of 'pseudo-lymphoid' leukaemia is described. The leukaemic cells resembled small, mature lymphocytes but lacked B- and T-cell membrane markers as well as immunoglobulin (Ig) and T-cell receptor gene rearrangements. They showed, instead, features of early myeloid cells since they expressed 2 myeloid antigens, CDW13 and My9, and displayed peroxidase activity demonstrable by electron microscopy (EM) on unfixed cells. Cytogenetic studies showed monosomy 5, t(4;17) (p12;p11), t(2;3)(p23;q14) and an abnormal chromosome 12. Abnormalities of chromosomes 4 and 5 have been previously associated with 'pseudo-lymphoid' leukaemias. This case illustrates the value of sensitive methods for the characterization of blast cells and for the precise diagnosis of leukaemias with apparent 'lymphoid' morphology.

Anticardiolipin antibodies: isotype distribution and phospholipid specificity

Quantitative isotype specific enzyme linked immunosorbent assay (ELISA) was used to determine the distribution of immunoglobulin isotypes and phospholipid specificities of anticardiolipin (anti-CL) antibodies in 40 patients with one or more of the following 'antiphospholipid (anti-PL) antibody associated clinical complications'--namely, thrombosis, fetal loss, thrombocytopenia. Twelve of 40 patients had IgG, IgM, and IgA anti-CL antibodies. Ten patients had IgG and IgM, five patients had IgG and IgA, and three patients had IgM and IgA anti-CL antibodies. There was no statistical association between any single isotype or any group of isotypes with thrombosis, fetal loss, or thrombocytopenia. The presence of IgG anti-CL antibodies in 36 of the 40 patients suggests that this isotype may be most important in determining clinical complications, but there were four patients without IgG anti-CL antibodies who also appeared susceptible to thrombosis, fetal loss, and thrombocytopenia. IgG, IgM, and IgA anti-CL antibodies bound the negatively charged phospholipids, phosphatidylserine and phosphatidylinositol, but not the zwitterionic phospholipid, phosphatidylcholine. There was no significant difference between binding to cardiolipin and binding to other negatively charged phospholipids, suggesting that the specificity of these antibodies is for negatively charged phospholipids in general rather than for cardiolipin in particular.

Mast cell leukemia: report of a case and review of the literature

We report the clinical and pathologic findings in one case of mast cell leukemia observed in a series of 60 patients with systemic mast cell disease. The leukemic variant of systemic mast cell disease is rapidly fatal (mean duration of survival, less than 6 months) in contrast to most nonleukemic cases, which follow an indolent clinical course. On the basis of our case and eight previously reported cases, mast cell leukemia is characterized by a substantial increase in atypical mast cells in the peripheral blood, diffuse infiltration with atypical mast cells in the bone marrow, a strong association with peptic ulcer disease, prominent constitutional symptoms, and hepatosplenomegaly. These cases should be distinguished from malignant mastocytosis without a substantial number of circulating atypical mast cells and also cases of acute nonlymphocytic leukemia that arise in the background of systemic mast cell disease.

Lineage ambiguity in acute leukemia

Two cases of acute nonlymphocytic leukemia that showed surface phenotypes characteristic of lymphoid cells are reported. The cases, both involving female patients were studied by a variety of methods including flow cytometry and karyotyping. In Case 1, the patient, a 10-year-old girl, had poorly differentiated myeloblasts (FAB M1), which were weakly positive for Sudan black B (SBB), but negative for alpha naphthyl acetate esterase (NAE) and naphthol ASD chloroacetate esterase (CAE). Myeloperoxidase was demonstrated ultrastructurally in some of the blasts. In Case 2, the 30-year-old patient had typical myelomonocytic leukemia (FAB M4), with SBB-, NAE-, and CAE-positive blasts. Both cases were negative for terminal deoxynucleotidyl transferase. Case 1 was negative for myeloid membrane markers, whereas Case 2 was strongly positive for My7 and My9. Surprisingly, both cases showed significant positivity for B-cell restricted antigens B1, B2, and B4. These findings suggest ambiguous or dual lineage, supporting the concepts that some leukemias could arise from a pluripotent hematopoietic progenitor cell (Case 1) or from cells that though differentiated in some respects, could still preserve some early antigens (Case 2).

Correlation between chromosomal abnormalities and blast phenotype in the blast crisis of Ph-positive CGL

We carried out cytogenetic analysis in 23 patients with Ph-positive chronic granulocytic leukemia in blast crisis. In all cases the type of blast cell was characterized by cytochemistry, immunologic markers, and ultrastructural studies. Twelve cases were classified as myeloid transformation, six as lymphoid, two as mixed (lymphoid and myeloid), and two were unclassifiable. Duplication of Ph was the most frequent abnormality in the whole series. Trisomy 8, i(17q) and trisomy 19 were seen only in patients with myeloid blast crisis (53%, 30%, and 23%, respectively). Our findings suggest that the nature of additional chromosome abnormalities arising in blasts with features of myeloid differentiation are different from those in blasts showing lymphoid differentiation.

Conversion of acute undifferentiated leukemia phenotypes: analysis of clonal development

The cellular origin of acute undifferentiated leukemia (AUL) is still a matter of controversy. We report on two cases in which the diagnosis of AUL was established according to restricted criteria. Blast cells of both patients showed phenotypic conversion during the course of disease. In one case, within 24 days from starting treatment, the leukemic phenotype changed from AUL to acute myelomonocytic leukemia (FAB L1, TdT+ to FAB M4, TdT-). The initial phenotype of this acute leukemia was characterized by the co-expression of both B-lymphoid and myeloid markers on the same cell. Moreover, analysis of esterase isoenzyme pattern showed the whole spectrum of isoenzymes typically seen in myelomonocytic leukemias already at diagnosis, yet blast cells additionally contained all three isoenzymes of beta-hexosaminidase typically seen in AUL. However, examination of immunoglobulin (Ig) heavy chain gene rearrangement initially and after conversion revealed an identical monoclonal configuration of Ig heavy chain sequences in both samples. The second AUL patient relapsed after allogeneic bone marrow transplantation with common ALL-antigen (CALLA) positive acute leukemia. Subsequent Southern blot analysis showed a novel rearranged Ig fragment compared to the analysis before transplantation indicating that the leukemic clones prior to and after transplantation were not identical. No chromosomal abnormalities were observed in both cases. These data support the view that AUL cells originate from a pluripotent stem cell that is capable to differentiate in the myelomonocytic lineage (patient 1), and confirm the value of Ig gene analysis as marker for cellular clonality.

Osteolytic lesion as the presenting feature of chronic granulocytic leukaemia

We describe a woman in whom the first manifestation of chronic granulocytic leukaemia (CGL) was an osteolytic lesion. Six months later the peripheral blood showed the picture of CGL in blast crisis. Chromosome studies confirmed the diagnosis and immunological and ultrastructural studies demonstrated the presence of two blast populations: basophil blasts and megakaryoblasts.

Characterization of blast cells in chronic granulocytic leukaemia in transformation, acute myelofibrosis and undifferentiated leukaemia. II. Studies with monoclonal antibodies and terminal transferase

A panel of 19 monoclonal antibodies (McAb) and the enzyme terminal transferase (TdT) have been applied to the characterization of poorly differentiated blasts from 50 patients with chronic granulocytic leukaemia (CGL) and myelofibrosis in blast crisis (BC), acute myelofibrosis and undifferentiated leukaemia. These cells were also extensively studied by transmission electron microscopy (TEM) (see Polli et al, 1985a). McAb against platelet glycoproteins (GP) showed a high specificity for megakaryoblasts, in particular those reactive with the GPIIb/IIIa complex (J15) and GPIIIa (C15 and C17), which were positive in a higher proportion of blasts than the McAb to GPIb (AN51 and FMC25). Findings with these anti-platelet McAb paralleled those of the platelet-peroxidase (PPO) reaction in 76% of cases studied simultaneously. The PPO reaction was always positive in cases in which two or more of the McAb were reactive with the blast cells. The differences observed suggest, nevertheless, that PPO is more sensitive for megakaryoblasts than the McAb and that this TEM technique should be reserved for cases which are negative with the platelet specific McAb. Of the McAb against myeloid antigens used in this series OKM1 was positive in 50% of cases but the others failed to demonstrate early features of differentiation in myeloblasts and monoblasts. In only three cases were erythroid precursors demonstrated by TEM and these were the only ones reactive with a McAb to glycophorin-A (LICR LON/R10). TdT and the McAb J5 helped in the identification of lymphoblasts which were seen as a 'pure' proliferation in 23% of CGL-BC and as part of blast cell mixtures in another 17% of cases. The McAb reactive to haemopoietic precursor cells (RFB1, FMC8 and OKIa), on the other hand, were of no practical value for the classification of blast cell types. The lineage specificity of several of the McAb used in this study, confirmed by TEM, suggest that these reagents are valuable tools for the characterization of immature blast cells.