Allogeneic bone marrow transplantation in children with myelodysplastic syndrome or juvenile myelomonocytic leukemia: the Seattle experience

The purpose of this study was to evaluate the role of allogeneic bone marrow transplantation (BMT) in children with myelodysplastic syndrome (MDS). In total, 94 consecutive pediatric patients with MDS received an allogeneic BMT from 1976 to 2001 for refractory anemia (RA) (n=25), RA with ringed sideroblasts (RARS) (n=2), RA with excess blasts (RAEB) (n=20), RAEB in transformation (RAEB-T) (n=14), juvenile myelomonocytic leukemia (JMML) (n=32) or chronic myelomonocytic leukemia (CMML) (n=1). The estimated 3-year probabilities of survival, event-free survival (EFS), nonrelapse mortality and relapse were 50, 41, 28 and 29%, respectively. Patients with RA/RARS had an estimated 3-year survival of 74% compared to 68% in those with RAEB and 33% in patients with JMML/CMML. In multivariable analysis, patients with RAEB-T or JMML were 3.9 and 3.7 times more likely to die compared to those with RA/RARS and RAEB (P=0.005 and 0.004, respectively). Patients with RAEB-T were 5.5 times more likely to relapse (P=0.01). The median follow-up among the 43 surviving patients is 10 years (range 1-25). We conclude that allogeneic BMT for children with MDS is well tolerated and can be curative.     

Clonality in myelodysplastic syndromes: demonstration of pluripotent stem cell origin using X-linked restriction fragment length polymorphisms

Restriction fragment length polymorphisms (RFLP) of the X-chromosome genes phosphoglycerate kinase (PGK) and hypoxanthine phorphoribosyltransferase (HPRT) were used to determine the clonal nature of myelodysplastic syndromes (MDS) in 22 patients. These included eight with refractory anaemia (RA), four with RA with ring sideroblasts (RARS), six with RA with an excess of blasts (RAEB), three with RAEB in transformation (RAEB-T), and one with chronic myelomonocytic leukaemia (CMML). Monoclonal X-inactivation patterns were observed in 19/22 patients. The remaining three cases, one each with RA, RARS and RAEB, were of polyclonal composition. Separated T-lymphocyte and granulocyte fraction analyses in six patients of the former cases revealed that T-lymphocyte as well as granulocyte fractions showed a monoclonal pattern of X-inactivation. These results support the view that the majority of MDS arise from a pluripotent stem cell capable of myeloid and lymphoid differentiation.     

Myelodysplastic syndromes, from French-American-British to World Health Organization: comparison of classifications on 431 unselected patients from a single institution.

In 1999 a working group of the World Health Organization (WHO) published a revised classification for myelodysplastic syndromes (MDS): RA, RARS, refractory cytopenia with multilineage dysplasia (RC+Dys), RAEB I and II, del (5q) syndrome, and MDS unclassifiable. Chronic myelomonocytic leukemia (CMML) and RAEB-t were excluded. Standard French-American-British (FAB) and new WHO classifications have been compared in a series of patients (n = 431) from a single center, analyzing morphologic, clinical, and cytogenetic data. According to the WHO findings, dysgranulocytopoiesis or dysmegakaryocytopoiesis only were found in 26% of patients with less than 5% medullary blasts. These patients are thus unclassified and should remain in the subgroups RA and RARS. Splitting of heterogeneous RAEB into 2 subgroups according to blast count was supported by a trend to a statistically significant difference in the single-center study population. Patients with CMML whose white blood cell counts are above 13 000/microL may be excluded from the MDS classification, as warranted by WHO, but a redistribution of patients with dysplastic CMML according to medullary blast count leads to more heterogeneity in other WHO subgroups. Although the natural courses of RAEB-T and acute myeloid leukemia (AML) with dysplasia are different, comparable median survival durations after treatment in patients with RAEB-T and AML were in favor of the proposed 20% medullary blast threshold for AML. The homogeneity of subgroups was studied by evaluating prognostic scores. A significant shift into lower IPSS risk groups was evident in the new classification. These data cannot provide evidence for the new WHO proposal, which should not be adopted for routine clinical use at present. Some of its aspects can provide a starting point for further studies involving refined cytogenetics and clinical results.     

Levels of soluble forms of ICAM and VCAM in patients with myelodysplastic syndromes and their prognostic significance

The aim of this study was to assess circulating soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and interleukin-1beta (IL-1beta) in myelodysplastic syndromes (MDS) in order to evaluate their clinical significance. Seventy patients with untreated MDS [21 refractory anemia (RA), nine RA with ringed sideroblasts (RARS), 17 RA with excess of blasts (RAEB), 11 RAEB in transformation (RAEBt), and 12 chronic myelomonocytic leukemia (CMML)] were included in this study. Serum levels of sICAM, sVCAM, and IL-1beta were determined at diagnosis using commercially available immunoassays. In addition, 15 healthy volunteers were studied as a control group. sICAM, sVCAM, and IL-1beta serum levels were significantly higher in MDS patients in comparison with the control group (P <0.001). Patients with CMML showed the highest sICAM, sVCAM, and IL-1beta levels in comparison with other MDS-related subtypes. Furthermore significantly elevated levels of the studied parameters were detected in high-risk MDS patients (RAEB, RAEB-t, and CMML) in comparison with low-risk MDS (RA and RARS). IL-1beta was strongly correlated both to sICAM and sVCAM. In conclusion we have provided evidence that increased sICAM and sVCAM serum levels are related to MDS severity.     

Detection of CD55- and CD59-deficient granulocytic populations in patients with myelodysplastic syndrome

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by absence of CD55 and CD59 from the surface of affected cells. PNH has been associated with myelodysplastic syndromes (MDS). The aim of our study was to estimate the prevalence of the PNH clone in MDS patients by detecting CD55 and CD59 deficiency. We studied 90 MDS patients: 19 patients with RA, 15 with refractory anemia with ringed sideroblasts (RARS), 18 with refractory anemia with excess of blasts (RAEB), 17 with refractory anemia with excess of blasts in transformation (RAEB-t), and 21 with chronic myelomonocytic leukemia (CMML). Twenty healthy individuals were also studied as the control group. We studied the PNH clone on granulocytes of these patients with the aid of flow cytometry. CD55- and CD59-deficient granulocytic populations were detected in 15.5% of MDS patients compared to 2.8% of normal individuals. Among the subgroups of the study, significant difference was present in three cases: (1) between CMML and control, (2) between CMML and RA, and (3) between CMML and RARS. These data indicate a possible association between PNH phenotype and MDS. MDS patients of worse prognosis (CMML) express more strongly the PNH clone compared to those of better prognosis (RA and RARS). Perhaps, the examination of MDS patients for the PNH clone by flow cytometry could provide us with a valuable prognostic tool.     

Bmi-1 is useful as a novel molecular marker for predicting progression of myelodysplastic syndrome and patient prognosis

The International Prognostic Scoring System (IPSS) has been widely used to predict the prognosis of patients with myelodysplastic syndrome (MDS). However, IPSS does not always provide a sufficiently precise evaluation of patients to allow the appropriate choice of clinical interventions. Here, we analyzed the expression of Bmi-1, which is required to regulate the self-renewal in CD34+ cells from 51 patients with cases of MDS and acute myeloid leukemia preceded by MDS (MDS-AML). Higher positivity rate of Bmi-1 was preferentially seen in refractory anemia with excess blasts (RAEB), RAEB in transformation (RAEB-T), and MDS-AML compared with refractory anemia (RA) and RA with ringed sideroblasts (RARS). IPSS score was positively correlated with the percentage of Bmi-1 expression. Patients with RA and RARS with a higher percentage of Bmi-1+ cells showed disease progression to RAEB. Here, we propose Bmi-1 as a novel molecular marker to predict the progression and prognosis of MDS.     

A clinical study on myelodysplastic syndrome. Report of 64 cases

Systematic clinical and laboratory observations of 64 cases of myelodysplastic syndrome (MDS) were made. The results showed that malignant clone already exists in the bone marrow of patients with MDS. Eighteen cases of them have transformed into AML. The rates of transforming into AML in RAEB, RAEB-T and CMML were markedly higher than that in RA. The courses of MDS which transformed into AML from the various types were different. The transformation in RA was obviously longer than those in RAEB and RAEB-T. Two cases transformed into myelofibrosis. Diagnosis of CMML according to the FAB classification criteria revealed that it has two forms. One shows only increase of mature monocytes and it has no relation with the types of acute leukemia to be transformed. It is considered as a reactive monocytosis. The other form, in addition to increase of mature monocytes, also has increase of a few monoblasts and promonocytes. These are considered as true CMML and usually quickly developed into M4 or M5 which are related with monocytes.     

Differential cellular expression of the human MSH2 protein in normal and myelodysplastic haematopoiesis

Loss of human MSH2 (hMSH2) protein might be involved in the multistep pathogenesis of haematological malignancies associated with genetic instability. Here, we examine cellular hMSH2 expression in bone marrow samples from 10 haematopoietically normal individuals in comparison with nine patients with myelodysplastic syndrome (MDS) [one refractory anaemia (RA), two RA with ringed sideroblasts (RARS), four RA with excess blasts (RAEB) and two RAEB in transformation (RAEB-T)]. HMSH2 protein was predominantly expressed in myeloblasts and promyelocytes. Blast cells from three patients with RAEB and one with RAEB-T displayed absent or very low hMSH2 expression. As no correlation between hMSH2 expression and chromosomal aberrations was observed, further genetic events seem to be required to induce karyotype instability.     

Clonal analysis of myelodysplastic syndromes: evidence of multipotent stem cell origin

Restriction fragment length polymorphisms (RFLPs) of the X-chromosome genes hypoxanthine phosphoribosyl transferase (HPRT) and phosphoglycerate kinase (PGK) were studied in 34 female patients with primary myelodysplastic syndromes (MDS). Twelve patients (35%) were heterozygous at the HPRT or PGK loci for BamHI or BglI RFLPs, respectively. In eight patients showing PGK polymorphisms, clonality was determined by X-chromosome inactivation analysis. These included patients from different morphologic subtypes: four with refractory anemia (RA), two with RA and ring sideroblasts (RARS), one patient with RA with excess of blasts (RAEB), and one with chronic myelomonocytic leukemia (CMML). A monoclonal pattern of X-chromosome inactivation was observed in seven cases. In a further case characterized by bone marrow hypoplasia, peripheral blood (PB) leukocytes were polyclonal in origin. Following low-dose cytarabine therapy, reversion to polyclonal hematopoiesis was observed in a case of RAEB indicating the presence of residual normal hematopoietic stem cells with the capacity for marrow reconstitution. The clonal relation of lymphoid and granulocyte/monocyte lineages was studied directly in two cases of CMML exhibiting somatic mutations of N-ras or Ki-ras oncogenes. By selective oligonucleotide hybridization to ras gene sequences amplified in vitro by the polymerase chain reaction, a mutated ras allele was demonstrated in PB granulocytes, monocytes, and B and T lymphocytes of both patients. We conclude that MDS arise from a multipotent hematopoietic stem cell with the potential for myeloid and lymphoid differentiation.     

Hemochromatosis-associated gene mutations in patients with myelodysplastic syndromes with refractory anemia with ringed sideroblasts

We observed increased ferritin levels in newly diagnosed MDS-RARS patients without transfusional iron-overload. Hence, we hypothesized RARS patients may harbor hemochromatosis-related mutations, which could contribute to the pathophysiology of this myelodysplastic syndromes (MDS) subset. We studied a cohort of 140 MDS patients: 42 with RARS, 10 with increased ringed sideroblasts, and 96 with other forms of MDS (43 RA, 27 RAEB, 17 RAEB-T, 8 MDS/MPD, 1 CMML). Patients were genotyped using restriction fragment length polymorphism, designed to detect C282Y and H63D mutations of the HFE gene. We found significantly higher frequency of heterozygosity for C282Y mutation in RARS patients compared with a large control population of matched race individuals (21 vs. 9.8% in controls, P = 0.03); H63D genotype was not significantly increased. Frequency of HFE variation in other MDS subtypes failed to differ significantly from controls. Within this group, we included patients with a rare form of MDS, provisionally subclassified by WHO as RARS with thrombocytosis (RARSt). 10/14 RARSt patients were carriers of either C282Y or H63D allele significantly increased compared with the combined prevalence in a healthy population (71 vs. 33%, P < 0.01). We found expected distribution of mutant HFE alleles in patients with other forms of MDS (9.1 vs. 9.8%, P = 0.82). Increased prevalence of HFE gene mutations is not a generalized feature of MDS, but some subgroups of MDS, especially those characterized by excessive accumulation of ringed sideroblasts, exhibit C282Y mutations at a higher frequency than in other forms of MDS and healthy controls.     

Prognostic implications of morphology and karyotype in primary myelodysplastic syndromes

Forty-nine patients with primary myelodysplastic syndromes (MDS) were subclassified according to French-American-British (FAB) Cooperative Group criteria. Eight patients had acquired idiopathic sideroblastic anemia (AISA), ten had chronic myelomonocytic leukemia (CMMoL), 14 had refractory anemia (RA), nine had refractory anemia with excess blasts (RAEB), and five had refractory anemia with excess blasts in transformation (RAEB-T); three patients could not be subclassified. The actuarial median survival for patients with AISA or with RA had not been reached at 60 months of follow-up. The median survival times for patients with CMMoL, RAEB, and RAEB-T were 25, 21, and 16 months, respectively. The percentages of patients with each subtype who developed ANLL were none in AISA, 20% in CMMoL, 7% in RA, 56% in RAEB, and 40% in RAEB-T. Patients with CMMoL had a poor prognosis independent of transformation to acute nonlymphocytic leukemia (ANLL), whereas patients with RAEB and RAEB-T had a high incidence of transformation and short survival times. Clonal chromosomal abnormalities were present in bone marrow cells from 19 patients at the time of diagnosis, and two others developed an abnormal karyotype at the time of leukemic transformation. The most frequent abnormalities, including initial and evolutionary changes, were trisomy 8 (9 patients), deletion of 5q (4 patients), and deletion of 20q (4 patients). The median survival times were 32 months for patients with an abnormal karyotype, and 48 months for those with a normal karyotype (P = 0.2). Specific chromosomal abnormalities were not associated with particular histologic subtypes; however, a high percentage of patients with RAEB and RAEB-T had an abnormal clone (89% and 80%, respectively). The percentages of patients with clonal abnormalities were 13% for AISA, 20% for CMMoL, and 29% for RA. The MDS transformed to ANLL in 42% of patients with an abnormal karyotype, compared to 10% of those with an initially normal karyotype (P less than .01). Among patients with RA, RAEB, and RAEB-T, the risk of leukemic transformation was confined to those with an abnormal karyotype (P less than .01). Thus, in the present study, morphology and karyotype combined were the best indicators of outcome in patients with MDS.     

Expression analysis of proteins involved in the non homologous end joining DNA repair mechanism, in the bone marrow of adult de novo myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are characterized by genetic instability which is associated with abnormal DNA repair mechanisms. The most lethal type of DNA damage are double strand DNA breaks (DSBs), which are mainly repaired by Non Homologous End Joining Mechanism (NHEJ), whose core enzyme components include the Ku70/Ku80 heterodimer, DNA–PKcs, XRCC4 and DNA Ligase IV. The aim of the present study was the analysis of expression of proteins required for NHEJ in bone marrow cells of adult de novo MDS and their association with clinical characteristics and prognosis. Our analysis included 48 cases of MDS; 19 RA, 5 RARS, 19 RAEB, 3 RAEB-T, 1 CMML, 1 transformation to AML according to FAB classification. The expression of the enzymes Ku70, Ku80, XRCC4, DNA-PKcs and Ligase IV was determined by Western Blotting. The mean Ligase IV expression value was significantly lower in MDS patients compared to normal controls (0.53 vs. 0.78, p?=?0.03). A negative correlation was found between karyotype risk group and Ligase IV values. (p?=?0.05). Moreover, Ku70 expression levels were significantly lower in patients with a good prognosis karyotype (p?=?0.04). Furthermore, a negative correlation between Ku70 expression values and Hb levels was observed (p?=?0.04). Finally, a positive correlation was observed between enzyme Ku70 expression values and level of blasts (p?=?0.04). Our findings suppor-t a potential role of NHEJ enzyme Ligase IV in the pathogenesis of MDS. Larger numbers of cases need to be screened in order to draw definite conclusion.     

Leukocyte-derived inhibitory activity in patients with myelodysplastic syndrome

Summary Leukocyte-derived inhibitory activity inhibiting the entry of normal progenitor cells of granulocytes and macrophages (CFU-GM) into the S-phase of a cell cycle was investigated in 16 patients with different forms of myelodysplastic syndrome (MDS). The presence of this inhibitory activity was analysed in medium conditioned with low-density cells obtained from peripheral blood of MDS patients. The inhibition rate was measured by ³H-thymidine suicide technique with subsequent cultivation of pretreated cells in semisolid agar medium. Low-density cells from MDS patients of various types were studied: from the twelve patients with refractory anaemia (RA or RAS) only three were positive, one patient with chronic myelomonocytic leukaemia (CMML) was negative while one patient with refractory anaemia with excess of blasts (RAEB) and two patients with RAEB in transformation (RAEB-T) were positive with respect of the described test. In two patients with RA, who underwent a long-term investigation, the production of leukocyte-derived inhibitory activity preceded the development of disease into RAEB or RAEB-T. In five positive cases, supernatants were incubated with antiserum against human placental ferritin; with one exception, the inhibitory activity was neutralized.     

Immunophenotypic clustering of myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are heterogeneous diseases of bone marrow (BM) cell precursors for which immunophenotypic characterization is still considered irrelevant despite the accuracy and sensitivity of flow cytometry techniques. The aim of this study was to determine whether immunophenotypic abnormalities could be defined in MDSs and could correlate with the French-American-British classification and cytogenetics. Analysis was performed on 275 BM samples (207 MDS patients, 68 controls) and 25 control blood samples. Immunophenotyping was based on a primary gating of blast cells, monocytes, and granulocytes according to CD45 antigen expression and side scatter light diffraction. Immunophenotypic hierarchical clustering was performed to analyze the results. The data obtained show that (1) immunophenotypic clustering partly discriminates patients with refractory anemia with excess blasts/refractory anemia with excess blasts in transformation (RAEB/RAEB-T), chronic myelomonocytic leukemia (CMML), and refractory anemia/refractory anemia with ring sideroblasts (RA/RARS) for CD45(lo) blast cells and patients with RA/CMML, RARS, and RAEB/RAEB-T for CD45(hi)/side scatter(hi) (SS(hi)) granulocytes; (2) the most discriminating markers were CD16, CD34, CD36, CD38, CD71, and HLA-DR for blast cells and CD11b, CD13, CD33, CD36, CD38, CD71, and HLA-DR for CD45(hi)/SS(hi) granulocytes; (3) clusters related to CD34 expression were associated with high levels of blast cells on BM smear; (4) clusters related to high levels of CD36 expression on CD45(lo) blast cells and CD45(hi)/SS(hi) granulocytes were associated with a poor International Prognosis Scoring System score; and (5) high levels of CD71 expression on CD45(hi)/SS(hi) granulocytes were associated with the RARS category. These results show a close relationship between immunophenotypic abnormalities and BM dysplasia and suggest that flow cytometry could be a future tool for the characterization of MDSs.     

Inhibitor of normal granulopoiesis produced by cells of MDS patients

Low-density blood cells from patients with refractory anemia with excess of blasts (RAEB) and RAEB in transformation (RAEB-T) release a high molecular weight inhibitory substance that reduces the entry of normal progenitor cells of granulocytes and macrophages (CFU-GM) into the S-phase. Out of 20 patients with refractory anemia (RA and RAS) only 3 were positive. One patient with CMML was negative. Serial examination of 3 patients (two RA and one CMML) revealed that the production of the inhibitory activity preceded the development of the disease into RAEB, RAEB-T, or AML. With one exception, the inhibitory activity in positive cases was neutralized by antiserum against human placental ferritin.     

Progression of refractory thrombocytopenia to chronic myelomonocytic leukemia accompanied by various inflammatory reactions

A 51-year-old man was admitted for treatment of severe thrombocytopenia in May 1997. A diagnosis of MDS RA (refractory thrombocytopenia; RTC) was made by bone marrow examination, which revealed mild marrow hypoplasia and a reduced number of megakaryocytes accompanied by micromegakaryocytes and hypolobular megakaryocytes. Chromosome analysis demonstrated 46, XY, t(5;7) (q31;q22) in all 20 cells examined. The patient received only supportive therapy including platelet transfusion, until leukocytosis and monocytosis gradually developed in November 1998. In view of a marked increase in the number of monocytes (more than 3,000/microliter), a diagnosis of CMML was made in December 1998. As the leukocytosis progressed, various inflammatory symptoms such as facial erythema and endophthalmitis developed. Administration of interferon alpha (IFN alpha) unexpectedly worsened the leukocytosis and monocytosis, suggesting abnormal responses of these cells to IFN alpha. Detailed molecular analysis of these cells might reveal a novel mechanism of leukemogenesis associated with 5q31.     

Clinical outcome in three patients with myelodysplastic syndrome showing polyclonal hematopoiesis

The clinical outcome of 3 myelodysplastic syndrome (MDS) patients with polyclonal hematopoiesis is reported. All patients were heterozygous for the phosphoglycerate kinase (PGK) gene. The presence of polyclonal hematopoiesis was determined by the X-chromosome-linked restriction fragment length polymorphism-methylation method using the PGK gene as a marker. The patients were initially diagnosed as having refractory anemia (RA), RA with ring sideroblasts (RARS), and RA with an excess of blasts (RAEB), respectively. Their pancytopenia persisted during the follow-up period of 11.4 years for the RA patient, 19.5 years for the RARS patient and 0.8 years for the RAEB patient. Although the RARS patient continues to be in good health, leukemic transformation occurred in the other 2 patients. A karyotype change from 46,XX to 45,XX,t(3;21),-7 was observed at the time of disease progression in the RA patient. The coexistence of a monoclonal MDS clone and normal bone marrow cells is thought to be the most probable reason for the polyclonal hematopoiesis of these patients.     

Risk assessment in myelodysplastic syndromes: value of clinical, hematologic and bone marrow histologic findings at presentation

We analyzed the prognostic value of clinical, hematologic and bone marrow (BM) histologic findings at presentation in 94 patients with myelodysplastic syndromes (MDS) (28 RA; 2 RARS; 34 RAEB; 6 CMML; 24 RAEB-t). With survival as the dependent variable, stepwise multivariate analysis indicated as the prognostically most important factors among the MDS taken as a whole: latency from the first symptoms to diagnosis, age, and percentage of BM blasts. In each main MDS group the most unfavorable initial characteristics were: 1) low Hb, no macro-megaloblastosis, male sex for RA/RARS; 2) low Hb and low platelet levels for RAEB/CMML; 3) granuloblastic hyperplasia and high BM blastosis for RAEB-t. Of the BM histologic parameters, only the percentage of blasts had significant prognostic value. Histologic assessment of BM blastosis, however, did not differ statistically from that based on cytologic examination of BM smears, so that marrow histology seemed not essential for initial prognostic assessment in MDS patients. The finding of abnormal localization of immature precursors (ALIP) in BM biopsies was associated with a negative trend without reaching statistical significance. Using four objective parameters of proven significance (age, Hb, platelets, and BM blasts) we devised a staging system of immediate clinical utility for prognostic stratification and risk-adapted therapeutic choices.     

Cytogenetic findings in 179 patients with myelodysplastic syndromes

Cytogenetic analyses were performed on 266 bone marrow and peripheral blood samples from 179 patients with myelodysplastic syndromes (MDS). According to the FAB classification, 42 patients presented with RA, 18 with RARS, 37 with RAEB, 22 with CMML, and 29 with RAEB-T. Nine patients showed a secondary MDS (S MDS). FAB classification was not available for 22 patients. Clonal karyotype anomalies were found in 92 patients (51.4%). Complex chromosome abnormalities occurred in 17 (18.5%) of them. An evolution of the karyotype was detected in 16 cases (17.4%). Cytogenetically independent cells or cell clones were found in eight patients. Nonclonal chromosome abnormalities were uncovered in 29 (16.2%) of the 179 MDS patients. Consecutive studies were performed in 48 patients and revealed a good correlation of initial karyotype and clinical course. The most frequent single anomalies were 5q- in 29 (31.5%), –7 in 22 (23.9%), trisomy 1q in 14 (15.2%), and +8 in 13 (14.1%) of 92 patients respectively. Our cytogenetic findings are presented in detail and discussed in relation to patients' age, morphological classification, clinical course, and prognostic impact. The contribution of cytogenetic findings to the delineation of multistep pathogenesis of MDS with special emphasis to karyotype instability is demonstrated.     

Myelodysplastic syndromes: analysis of 131 cases according to the FAB classification

The clinical and haematological findings in 131 patients with myelodysplastic syndromes (MDS), none of which had previously received chemotherapy or radiotherapy, classified according to the FAB criteria, were analysed. The distribution among the 5 subgroups was: RA 31 patients, RAS 19, RAEB 23, CMML 29 and RAEBT 29 patients. There were difficulties in the classification of 24 patients. These included, first, 8 cases with myeloid hyperplasia of the bone marrow (BM) but without monocytosis or excess of blasts of the BM. They were classified as RA. Second, 8 cases with sideroblastosis but with monocytosis or excess of blasts of the BM were classified 3 as RAEB, 2 as CMML and 3 as RAEBT. Finally, 8 cases with absolute monocytosis and BM blasts 15-30% were classified as CMML. 37 of 82 dead patients (45.1%) had transformed to acute non-lymphoblastic leukaemia (ANLL). The incidence of evolution to ANLL was low for RA and RAS (6.30% and 12.5% respectively), while it was 37.5% for RAEB, 57.1% for CMML and 77.2% for RAEBT. The median survival for each subgroup was: RA 18 months; RAS 25; RAEB 13; CMML 14 and RAEBT 10 months. It is concluded that the FAB classification with some modifications recognises group of MDS with different prognosis.