Acute myeloblastic leukemia with minimal myeloid differentiation: phenotypical and ultrastructural characteristics

Leukemia (1998) 12, 1071–1075  1998 Stockton Press All rights reserved 0887-6924/98 $12.00 http://www.stockton-press.co.uk/leu

Acute myeloblastic leukemia with minimal myeloid differentiation: phenotypical and ultrastructural characteristics N Villamor1, M-A Zarco2, M Rozman1, J-M Ribera2, E Feliu2 and E Montserrat1 1

Servei d’Hematologia, Hospital Clinic de Barcelona; and 2Servei d’Hematologia, Hospital Universitari Germans Trias i Pujol, Badalona, Spain

AML-M0 is an infrequent form of acute myeloblastic leukemia characterized by negative reaction with myeloperoxidase (MPO), Sudan Black and lymphoid antigens and positivity for CD13 or CD33. In the present study we describe the immunophenotypical and ultrastructural characteristics of a group of AML-M0 in adult patients. Nine out 218 AML leukemias (4.1%) fulfilled the AML-M0 criteria. CD13 or CD33 were positive in eight out nine cases, with two or more positive myeloid antigens being present in 82% of the cases. Immunological MPO was positive in 57% of the cases and CD68 in 33%. In no case were megakaryocytic and erythroid markers present. Four cases (44%) expressed CD7 and TdT but only two coexpressed both antigens. In none of the cases was CD3 or CD22 cytoplasmic expression found. Ultrastructurally, a low number of granules was seen in all cases whereas ferritin particles or rhopheocytosis were not observed. Ultrastructural MPO was positive in one out of five cases and platelet peroxidase (PPO) was negative in the four cases studied. Two out of six cases showed karyotypic abnormalities (hypotetraploidy and a complex karyotype, respectively). In two out three cases a rearranged pattern for JH gene was observed. TCR (C␤ and J␥) rearrangements were not detected in any case. AML-M0 is an infrequent form of acute myeloblastic leukemia. A large panel of myeloid monoclonal antibodies (MoAb) and the study of the cytoplasmic expression of myeloid antigens is necessary to diagnose this form of leukemia. AML-M0 usually coexpress lymphoid markers. Ultrastructural studies may be of help to discard an immature erythroid proliferation. Keywords: acute myeloid leukemia; AML-MO; ultrastructure; immunophenotype

Introduction The French–American–British (FAB) co-operative group proposed morphological, cytochemical and immunophenotypical criteria to identify a new type of acute myeloblastic leukemia (AML) with minimal myeloid differentiation which is known as AML-M0.1 This is an infrequent form of leukemia which, according to the FAB group, represents less than 5% of all acute myeloblastic leukemias. The main characteristic of this new AML subtype is the agranular cytoplasm of the blast cells resembling lymphoblastic cells and the negative cytochemical reactions for myeloperoxidase and Sudan Black. The myeloid origin of the blast cells is demonstrated by the presence of myeloid antigens (CD13 or CD33) and the lack of expression of lymphoid markers. We describe the characteristics of a series of nine patients with AML-M0 with special emphasis on the immunophenotypic pattern and the ultrastructural features of these cases.

Correspondence: Prof E Montserrat, Servei d’Hematologia, Hospital Clinic de Barcelona, c/Villarroel 170, 08036 Barcelona, Spain; Fax: 343 227 54 75 Received 25 September 1997; accepted 24 March 1998

Material and methods

Patients During a 4 year period 82 de novo acute lymphoblastic leukemias, 218 de novo acute myeloblastic leukemias and five undifferentiated leukemias were diagnosed in the Hospital Clinic de Barcelona, Barcelona, and the Hospital Universitari Germans Trias i Pujol, Badalona, in patients older than 15 years.

Classification of acute leukemias Morphology and cytochemistry: Acute leukemias were classified according to the FAB criteria.1–4 Peripheral blood ¨ and bone marrow smears were stained with May–Grunwald– Giemsa. Cytochemical reactivity against myeloperoxidase (MPO), Sudan Black, naphtol-ASD-acetate with FINa inhibition and alpha-naphtyl acetate was analyzed. Immunophenotype: Immunocytochemical analysis by alkaline phosphatase anti-alkaline phosphatase technique5 and/or immunofluorescence technique and flow cytometry of peripheral and/or bone marrow samples were performed to determine the expression of lymphoid and myeloid antigens in blast cells. Reactivity against B and T lymphoid antigens (Tdt, CD19 or cytoplasmic CD22, CD10, CD7, cytoplasmic CD3) as well as myeloid antigens (CD33 or cytoplasmic CD13, CD14, CD68, myeloperoxidase) and HLA-DR expression was investigated. In addition, in most cases the presence of CD2, CD5, CD11b, CD41 or CD61, CD36, glycophorin A, and CD34 was tested. An acute leukemia was considered as positive for an antigen when more than 20% of the blast cells reacted with it (⬎10% in the case of immunological myeloperoxidase (iMPO). Ultrastructural morphology: Mononuclear cells of peripheral blood or bone marrow were processed by electron microscopy. Cells were fixed in 1.25% glutaraldehyde in 0.1 M cacodylate buffer, postfixed in fresh 1.25% glutaraldehyde for 2 h at 4°C, followed by 1% OsO4 and dehydrated through a graded series of ethanol. Dehydrated samples were included in Durcupan. Thin sections were cut on a Reichert’s ultramicrotome, mounted on copper grids, stained with uranyl acetate and lead citrate and examined in a Philips 410 electron microscope.6 In each case a minimum of 25 blast cells was studied, counting the number of granulated blast cells, the number of granules per blast section, the nuclear outline and the presence of cytoplasmic organelles. To detect ultrastructural myeloperoxidase bone marrow particles or buffy-coat cells were fixed for 30 min at 4°C with 1.25% distilled glutaraldehyde in 0.1 M phosphate buffer, pH 7.2. Cells were washed three times in the

Phenotypic and ultrastructural characteristics of AML-MO N Villamor et al

1072

buffer. Samples were incubated for 30 min at room temperature in the dark in DAB medium. The cells were then rinsed in several changes of phosphate buffer, 0.1 M pH 7.2, and postfixed for 30 min in osmium tetroxide in phosphate buffer. After postfixation the cells were dehydrated in graded ethanol solutions and embedded in epoxyresin. Ultrathin sections were examined either unstained or slightly stained with lead citrate.6 Ultrastructural platelet peroxidase: cells were fixed in 1.25% glutaraldehyde in Gey’s buffer at 4°C for 10 min, washed three times with the same buffer and incubated in DAB medium for 60 min at room temperature in the dark; the remaining steps were carried out as in usual MPO staining.6

Karyotypic analysis Chromosomal analysis was performed in peripheral or bone marrow specimens. Mononuclear cells were cultured in RPMI 1640, supplemented with 20% heat-inactivated fetal calf serum enriched with 2% L-glutamine, 100 ␮g/ml penicillin, 10 ␮g/ml streptomycin, 1% sodium heparin. Chromosome preparations were obtained after 24–48 h of incubation. The slides were stained with a G-banding. Well-spread metaphases were photographed and then arranged according to the recommendations of the International System for Human Cytogenetic Nomenclature.7

Organization of immunoglobulin gene and beta chain gene of T cell receptor High molecular weight DNA was obtained by lysis of leukemic cell samples with sodium dodecylsulphate (SDS) and proteinase K, followed by extraction with phenol-chloroform and chloroform and further precipitation with ethanol.8 The DNA samples were digested with restriction endonucleases EcoRI, and HindIII (Boehringer Mannheim, Mannheim, Germany). DNA fragments were size fractioned by electrophoresis in 0.8% agarose gel and transferred to nitrocellulose filters. The probes were labeled by a random priming method to a specific activity of 1 to 2 × 109 c.p.m./␮g of DNA. After hybridization, the filters were washed stringently at 65°C, dried, and autoradiographed. Ig gene analysis was performed using a 2.5 Kb EcoRI/PvuI fragment corresponding to the joining region of the immunoglobulin heavy chain (JH). The organization of T cell receptor was analyzed using a 0.8 kb (HindIII/EcoRI) fragment for the joining region of the T cell receptor ␥ chain gene (J␥) and a 0.6 kb (HindIII/EcoRI) fragment for constant region of the T cell receptor ␤-chain (C␤). The presence of breakpoints in the major breakpoint cluster region was investigated using bcr-3 probe (MBR) with a 2 kb fragment corresponding to the M-bcr gene. These probes were kindly provided by Dr L Luzzatto, from the Department of Human Genetics, Memorial Sloane Kettering Cancer Center, New York, USA.

Statistical analysis Quantitative values were expressed as mean ± standard deviation (s.d.). Student’s t-test was used for comparing quantitative values between AML groups and the ANOVA test for qualitative parameters.

Results The FAB distribution of AML was as follows: nine M0, 36 M1, 30 M2, 37 M3, 30 M4, 64 M5, nine M6, three M7. Thus, the frequency of AML-M0 in our AML series was 4.1%, without differences between the two centers contributing cases. The main clinical and analytical data of these patients as well as their outcome are depicted in Table 1.

Morphological and cytochemical characteristics The morphological appearance of blast cells was lymphoid in seven cases (78%) and myeloid in two (22%). The myeloperoxidase and Sudan Black reactions were negative in all cases, while esterases were negative in all cases but two which showed low intensity reaction in a few blast cells. In the three patients who relapsed (Nos 1, 4, 7) after having achieved a remission the morphological and cytochemical characteristics of the blast cells at relapse were the same as those at diagnosis. In one of the two patients with refractory disease (No. 2) the appearance of Auer rods in 15% of cells and myeloperoxidase restricted to the Auer rods was noticed 6 months after the diagnosis.

Immunophenotype Table 2 shows the immunophenotype of AML-0 cases. All cases were negative for B lineage antigens (CD19, cytoplasmic CD22 and CD10). Cytoplasmic CD3 was negative in all cases, one case was CD2 positive (11%) and four cases were CD7 positive (44%). The mean percentage of CD7+ blast cells was 59% (s.d. 27, range 35–91%). Four cases (44%) were Tdt positive with a mean value of 43% (s.d. 21, range 20–63%). Only two cases coexpressed CD7 and TdT. HLA-DR was positive in all but one case and CD34 in five out of eight cases (63%). Six patients out of nine (67%) were CD13 positive with a mean value of 69% (s.d. 18, range 44–95%). Four out of six cases (67%) were CD33 positive with a mean value of positive cells of 47% (s.d. 10, range 35–58%). Three out of nine cases (33%) were CD68 positive with a mean positivity of 62% (s.d. 19, range 51–84%). CD14 was positive in one out of seven cases (14%) and CD11b was positive in two out of seven cases (29%). In seven AMLM0 the expression of myeloperoxidase was analyzed by immunological technique (iMPO). In four cases, more than 10% of the blast cells were positive with a mean percentage of 27 (s.d. 13, range: 11–42%). In most cases the blast cells reacted with more than one myeloid antigen: two cases (22%) expressed one myeloid marker (CD13 and CD33); three (33%) were positive for two myeloid antigens (CD13 and CD14, CD68 and iMPO, CD13 and CD68) and four (44%) reacted with three myeloid antigens (CD13, CD33 and iMPO; CD13, CD33 and CD11b; CD33, CD11b and iMPO; CD13, CD68 and iMPO). No case was positive for megakaryocytic antigens (CD41 or CD61) or glycophorin A. Table 3 compares the immunophenotype of AML-M0 with the other AML subtypes. CD7 was found to be more frequently expressed in AML-M0 than in the other AML varieties. In contrast, iMPO expression was less frequent in AML-M0 than in the other subtypes. In three patients the immunophenotype was also analyzed at relapse. In patient No. 4 the percentage of blast cells expressing CD33 increased and iMPO became positive, and in patient No. 7 the percentage of CD33-positive blast cells increased whereas CD14 became positive and CD7 expression was lost.

Phenotypic and ultrastructural characteristics of AML-MO N Villamor et al

Table 1

1073

Clinical and analytical characteristics of AML-M0 patients

1

2

3

4

Patient No. 5

6

7

8

9

Age/sex Adenomegaly Hepatomegaly Splenomegaly

56/M No No No

61/M No No No

55/M No No No

23/M No No No

71/F No No 3 cm

72/F No No No

39/M Yes No No

80/M Yes No No

68/F No 2 cm No

Peripheral blood Hemoglobin (g/l) Leukocytes (×109/l) Blasts cells (%) Platelets (×109/l)

63 2.8 22 128

115 1.7 50 233

56 6.7 56 *

125 18.0 92 66

68 1.2 8 84

102 1.4 0 202

122 115 79 204

90 155 98 29

80 1.8 22 60

Bone marrow Morphology Blasts cells (%) Myeloperoxidase Sudan Black ANAE

My 58 1.4 0 ±

Ly 48 1.3 0 −

Ly 70 1.6 0 30

Ly 99 2.4 0 −

Ly 51 0 0 −

My 71 0 0 ±

Ly 83 0 0 −

Ly 58 0 0 −

Ly 47 2 0 −

DAE Yes Yes (48) 53

DAE No * 27

DAE Yes No 6+

DAE1 Yes Yes (15) 21

No * * 3

DAE No * 28

DAE2 Yes Yes (10) 20

MX-ARA * * 0.5

DAE Yes No 63+

Treatment Chemotherapy Complete remission Relapse (months) Survival3

M, male; F, female; My, myeloid; Ly, lymphoid; *, not done or not applicable; −, negative. Chemotherapy (administered according to Sierra et al)29: DAE, daunorubin, cytarabine and etoposide; 1followed by ABMT, 2ABMT in second remission; survival3: + alive. Table 2

Immunophenotypical results of AML-M0 patients

1

2

3

4

Patient 5

6

7

8

9

TdT DR CD34

32 79 44

− 85 74

− 78 7

20 67 78

− 78 7

− 12 *

− 18 52

58 65 *

− 98 77

− 85 94

− 62 86

63 99 9

CD19 cCD22 CD10

− * −

− − −

− − −

− − −

− − −

− − −

− − −

− − −

− − −

− − −

− − −

− − −

cCD3 CD7 CD2 CD5

− 35 − −

− 35 − −

− − − −

− 9 − −

− 72 − −

− 94 − −

− − − −

− 39 * *

− 91 − −

− − − −

− − 34 −

− − * −

cCD13 CD33 CD14 CD11b CD68 CD36 CD41/CD61 MPO Glyco-A Methodology

68 58 − 17 − * − 42 − C

83 58 − 12 3 − − 7 − C

95 * 40 * − − − * * C

54 − − − − * − − − I

− 35 − − − * − − − C

− 66 − 6 13 − − 8 * C

75 46 − 20 2 * − * * C

− * * − 52 − − 30 * I

75 10 − − 84 * − − − C

78 97 20 14 * − − 1 * C

4 50 − 61 16 − − 27 * C

44 * * * 51 * − 11 * 1

*, not done; −, negative. Second column, results at relapse. C, combined flow cytometry and immunocytochemistry. I, immunocytochemistry.

Cytogenetics and molecular biology A sufficient number of metaphases was obtained in six cases with four normal karyotypes, one case with hypotetraploidy (79-88; XXXX [20]), and one case with complex karyotype with 13 metaphases; in spite of bad morphology preventing a clear definition of the breakpoints it was possible to identify the following abnormalities [46XY, t(6;11)(q?;q23)/46XY del(6)(q?)/46XY del(3) (q2)]. TCR ␤-chain and J␥ configuration was normal in the three

patients studied. In contrast, two patients showed a rearranged pattern in the JH region of the immunoglobulin gene (see Table 4). None of the patients showed rearrangements in the bcr gene.

Ultrastructure Ultrastructural analysis was performed in eight patients. In all cases, the blast cells showed cytoplasmic granulation (ranging from 4 to 80% of blasts). The number of granules per section

Phenotypic and ultrastructural characteristics of AML-MO N Villamor et al

1074

Table 3 Immunological characteristics of AML-M0 compared with the other FAB subtypesa

M0 CD7+ CD7(%)b

M1–M2

3/6 6/38 35.0 ± 39.9 5.7 ± 17.3

M3

M4–M5

P

0/14 0±0

7/47 2.7 ± 7.4

0.02

1/6 17/37 11/11 32/40 0.001 CD68+ CD68(%)c 11.2 ± 20.1 28.1 ± 33.7 75.1 ± 22.8 40.6 ± 30.1 1/5 30/34 14/14 20/38 0.001 iMPO+ iMPO(%)d 12.1 ± 17.7 64.3 ± 39.7 97.4 ± 7.0 27.4 ± 34.7 CD14 CD14(%)

1/6 6/35 2/13 15/38 8.0 ± 17.9 11.0 ± 23.4 1.8 ± 5.7 24.1 ± 29.7

NS

TdT+ TdT(%)e

2/6 6/38 19.0 ± 25.3 9.4 ± 21.1

NS

0/14 0.1 ± 0.3

7/47 9.6 ± 22.0

a

Data from the Department of Hematology, Hospital Clinic, Barcelona. P ⬍ 0.05 between M0 and the other three subgroups. P ⬍ 0.05 between M3 and the other three subgroups. d P ⬍ 0.05 between M0 and M3, M0 and M1–M2, M4–M5 and M3, and M4–M5 and M1–M2. e P ⬍ 0.05 between M0 and M3. NS, not significant. b c

ranged from 1 to 20. The cytoplasm was scarce in five cases and abundant in three. In five cases, abundant mitochondria were seen and prominent Golgi apparatus and RER were seen in one case. No ferritin particles, ␪ granules or rhopheocytosis vesicles were observed. The nuclear outline was regular in 43% of the cases and irregular in 57%. Ultrastructural reaction for platelet peroxidase was negative in the four cases tested. Ultrastructural myeloperoxidase was positive, restricted to the granules, in 12% of the blast cells in one out of the five cases studied. Discussion The AML-M0 is a recently described AML subtype with a reported frequency ranging from 4% according to the FAB group1 to 10% found in a recent report.9 Only after the introduction of immunophenotyping on a routine basis in the diagnosis of acute leukemias has it been possible to identify the AML-M0 subtype. The reactivity with myeloid-specific MoAb is the main criTable 4

terion for the diagnosis of this subtype of AML. Most of our cases (78%) were positive for two or more myeloid antigens. The high heterogeneity in the antigens expressed is of note. Interestingly, only the use of CD13 and CD33 may be insufficient for the diagnosis of AML-M0.10–12 Thus, the use of a large panel of myeloid MoAb and the analysis of cytoplasmic expression of the antigens is often necessary to detect these cases.13 In half of our cases immunological MPO was positive. The discordance between cytochemical and immunophenotypical MPO expression has been previously referred to, this being particularly frequent in the poorly differentiated AML subtypes.10,12,14 Although in the FAB criteria the negativity of lymphoid markers was considered as a criterion for the diagnosis of AML-M0, a high percentage of such forms of leukemia express lymphoid antigens, mainly CD7 and TdT, as observed in our series and others.9,11,15–18 The minimal myeloid features and the high frequency of CD7 or TdT expression may pose diagnostic difficulties. In fact, acute leukemias sharing identical immunophenotypic patterns can be differently classified (eg biphenotypic leukemias included in the AML-M0 subtype or the opposite) depending on the studies.19,20,21 In order to overcome this problem, strict criteria to diagnose biphenotypic leukemias have been proposed.22 None of our cases can be considered as a biphenotypic leukemia according to the latter criteria. Nevertheless, in some cases to discard an immature T cell acute lymphoblastic leukemia with some aberrant myeloid antigens can be difficult. In this regard, none of our patients showed cytoplasmic CD3 or a rearranged pattern for C␤ or J␥ chain of TCR. As shown in our study, ultrastructural morphological study can be useful in the diagnosis of AML-M0 by revealing the presence of granules in the cytoplasm of the blast cells. Ultrastructural MPO reaction was only positive in one of the five cases tested with a granular pattern similar to that observed in other undifferentiated acute leukemias.23,24 The disagreement between immunological and ultrastructural MPO detection could be explained by technical differences (functional vs immunological detection) and the low percentage of positive cells. It has been suggested that some AML-M0 could be of erythroid origin.15 There are no specific markers for very immature erythroid cells, the ultrastructural analysis of the cells being necessary for their detection.25 None of our patients showed the presence of invaginated pinocytic vesicles related to the intake of ferritin molecules at ultrastructural level, thus excluding the presence of blasts of erythroid lin-

Cytogenetic, molecular biology and ultrastructural characteristics of AML-M0

1

2

3

4

Patient 5

6

7

8

9

Ultrastructure Nucleus Nucleoli % granulated No. granules MPO PPO

76%I 88% 80 2–20 12% −

60%I 80% 56 1–14 * *

56%R 48% 20 1–2 * *

80%R 60% 36 1–9 * *

56%R 60% 40 1–10 − −

36%I 88% 36 1–9 − −

48%I 68% 4 1–2 − *

80%I 87% 40 1–3 − −

* * * * * *

Cytogenetics

*

46XY

*

46XY

46XX

Hypotetr.

46XY

Complex

*

Molecular biology JH C␤ J␥ 3⬘bcr

* * * *

* * * *

R G G G

R G G G

* * * *

* * * *

G G G G

* * * *

* * * *

Phenotypic and ultrastructural characteristics of AML-MO N Villamor et al

eage. In addition, none of our cases expressed ultrastructural platelet peroxidase and were negative for the specific megakaryocytic lineage markers CD61 and CD41.25,26 Recent reports10,16,27 suggest that genetic abnormalities in AML-M0 are frequently complex although without specific non-random abnormalities. Only one of our patients showed a complex karyotype and a translocation with a breakpoint in 11(q23) that has been associated with MLL gene in acute leukemias.28 In conclusion, AML-M0 is an infrequent type of AML with a phenotypical profile that can induce a misdiagnosis. The use of monoclonal antibodies highly specific for each lineage, the study of cytoplasmic antigens and the ultrastructural morphology allow the confirmation of the myeloid origin and to discard the presence of an immature erythroid or megakaryocytic proliferation among AML-M0 cases.

Acknowledgements This work was partially supported by grants from Fondo de Investigaciones Sanitarias de la Seguridad Social, Ministerio de Sanidad (FIS 94/0839, 95/0257).

References 1 Bennett JM, Catovsky D, Daniel MT, Flandrin G, Galton DAG, Gralnick HR, Sultan C. Proposal for the recognition of minimally differentiated acute myeloid leukemia (AML-M0). Br J Haematol 1991; 78: 325–329. 2 Bennett JM, Catovsky D, Daniel MT, Flandrin G, Galton DAG, Gralnick HR, Sultan C. Criteria for the diagnosis of acute leukemia of megakaryocyte lineage (M7). A report from the French–American–British cooperative group. Ann Intern Med 1985; 103: 460–462. 3 Bennet JM, Catovsky D, Daniel MT, Flandrin G, Galton DAG, Granick HR, Sultan C. Proposals for the classification of the acute leukaemias. Br J Haematol 1976; 33: 451–458. 4 Bennet JM, Catovsky D, Daniel MT, Flandrin G, Galton DAG, Gralnick HR, Sultan C. Proposed revised criteria for the classification of acute myeloid leukemia. A report from the French– American–British cooperative group. Ann Intern Med 1985; 103: 620–625. 5 Davey FR, Erber WN, Gatter KC, Mason DY. Immunophenotyping of acute myeloid leukemia by immunoalkaline phosphatase (APAAP) labelling with a panel of antibodies. Am J Hematol 1987; 26: 157–166. 6 Rozman C, Woessner S, Feliu E, Lafuente R, Berga L. Cell Ultrastructure for Hematologists. Doyma: Barcelona, 1993. 7 An International System for Human Cytogenetic Nomenclature. Recommendations of the International Standing Committee of Human Cytogenetic Nomenclature. Felix Mitelman (ed). Karger: Basel, 1995. 8 Maniatis T, Fritsch EF, Sambrook J. Molecular Cloning: A Laboratory Manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1982. 9 Venditti A, Del Poeta G, Stasi R, Masi M, Bruno A, Buccisano F, Cox C, Coppetelli U, Aronica G, Simone MD, Tribaldo M, Amadori S, Papa G. Minimally differentiated acute myeloid leukemia (AML-M0): cytochemical, immunophenotypic and cytogenetic analysis of 19 cases. Br J Haematol 1994; 88: 784–793. 10 Venditti A, del Poeta G, Stasi R, Buccisano F, Aronica G, Bruno A, Cox C, Maffei L, Tamburini A, Papa G, Amadori S. Biological profile of 23 cases of minimally differentiated leukemia (AML-M0) and its clinical implication (letter). Blood 1996; 87: 418–420. 11 Venditti A, Del Poeta G, Buccisano F, Tamburini A, Cox C, Stasi R, Bruno A, Aronica G, Maffei L, Suppo G, Simone MD, Forte L, Cordero V, Postorino M, Tufilli V, Isacchi G, Masi M, Papa G, Amadori S. Minimally differentiated acute myeloid leukemia

12

13

14

15

16

17 18 19

20

21

22 23

24

25 26 27 28 29

(AML-M0): comparison of 25 cases with other French–American– British subtypes. Blood 1997; 89: 621–629. Lepelley P, Preudhomme C, Sartiaux C, Ghevaert C, Lai JL, Iaru T, Fenaux P, Cosson A. Immunological detection of myeloperoxidase in poorly differentiated acute leukemia. Eur J Hematol 1993; 50: 155–159. Urbano-Ispizua A, Matutes E, Villamor N, Sierra J, Pujades A, Reverter JC, Feliu E, Cervantes F, Vives-Corrons JL, Montserrat E, Rozman C. The value of detecting surface and cytoplasmic antigens in acute myeloid leukaemia. Br J Haematol 1992; 81: 178–183. Buccheri V, Shetty V, Yoshida N, Morilla R, Matutes E, Catovsky D. The role of an anti-myeloperoxidase antibody in the diagnosis and classification of acute leukaemia: a comparison with light and electron microscopy cytochemistry. Br J Haematol 1992; 80: 62–68. Cuneo A, Ferrant A, Michaux JL, Boogaerts M, Demuynck H, van Orshoven A, Criel A, Stul M, Dal Clin P, Hernandez J, Chatelain B, Doyen C, Louwagie A, Castoldi G, Cassiman JJ, Van Den Berghe H. Cytogenetic profile of minimally differentiated (FAB M0) acute myeloid leukemia: correlation with clinicobiological findings. Blood 1995; 85: 3688–3694. Stasi R, del Poeta G, Venditti A, Masi M, Stipa E, Dentamaro T, Cox C, Dallapiccola B, Papa G. Analysis of treatment failure in patients with minimally differentiated acute myeloid leukemia (AML-M0). Blood 1994; 83: 1619–1625. Drexler HG, Sperling C, Ludwig WD. Terminal deoxynucleotidyl tranferase (TdT) expression in acute myeloid leukemia. Leukemia 1993; 7: 1142–1150. Drexler HG, Thiel E, Ludwig WD. Acute myeloid leukemias expressing lymphoid-associated antigens: diagnostic incidence and prognostic significance. Leukemia 1993; 7: 489–498. Basan R, Biondi A, Benvestito S, Tini ML, Abbate M, Viero P, Borleri G, Barbui T. Acute undifferentiated leukemia with CD7⫹ and CD13+ immunophenotype. Lack of molecular commitment and association with poor prognostic features. Cancer 1992; 69: 396–404. ´ ´ ´ Vidrales MB, Orfao A, Gonzalez M, Hernandez JM, Lopez-Berges MC, Garcia MA et al. Expression of NK and lymphoid-associated antigens in blast cells of acute myeloblastic leukemia. Leukemia 1993; 12: 2026–2029. Yokose N, Ogata K, Ito T, Miyake K, An E, Inokuchi K, Yamada T, Gomi S, Tanabe Y, Ohki I, Kuwabara T, Hasegawa S, Shinohara T, Dan K, Nomura T. Chemotherapy for minimally differentiated acute myeloid leukemia (AML-M0). A report of five cases and review of the literature. Ann Hematol 1993; 66: 67–70. Matutes E, Catovsky D. The value of scoring systems for the diagnosis of biphenotypic leukemia and mature B-cell disorders. Leuk Lymphoma 1994; 13 (Suppl. 1): 11–14. Vainchenker W, Villeval JL, Tabilio A, Matamis H, Karianakis G, Guichard J et al. Immunophenotype of leukemic blasts with small peroxidase-positive granules detected by electron microscopy. Leukemia 1988; 2: 274–281. Heil G, Gunsilius E, Hoelzer D, Thiel E, Heimpel H. Peroxidase expression in acute unclassified leukemias: ultrastructural studies in combination with immunophenotyping. Leuk Lymphoma 1994; 14: 103–109. Breton-Gorius J. Review of the ultrastructural and cytochemistry of megakaryoblastic leukemia. In Poliack A (ed). Human Leukemias. Martinus Nijhoff: Boston, 1984, pp 63–92. Koike T. Megakaryoblastic leukemia: the characterization and identification of megakaryoblasts. Blood 1984; 64: 683–692. Segeren CM, de Jong-Gerrits GCMM, van’t Veer MB. AML-MO: clinical entity or waste basket for immature blastic leukemias? A description of 14 patients. Ann Hematol 1995; 70: 297–300. Rubnitz JE, Behm FG, Downing JR. 11q23 rearrangements in acute leukemia. Leukemia 1996; 10: 74–82. ˜ Sierra J, Brunet S, Granena A, Olive T, Bueno J, Ribera JM, Petit J, Besses C, Llorente A, Guardia R, Macia J, Rovira M, Badell I, Vela E, Diaz Heredia C, Vivancos P, Carreras E, Feliu E, Montserrat E, Julia A, Cubells J, Rozman C, Domingo A, Ortega JJ. Feasibility and results of bone marrow transplantation after remission induction and intensification chemotherapy in de novo acute myeloblastic leukemia. J Clin Oncol 1996; 14: 1353–1363.

1075