Bone marrow cellularity in myeloid stem cell disorders: impact of age correction

MarrowQuant 2.0: A Digital Pathology Workflow Assisting Bone Marrow Evaluation in Experimental and Clinical Hematology

Bone marrow (BM) cellularity assessment is a crucial step in the evaluation of BM trephine biopsies for hematologic and nonhematologic disorders. Clinical assessment is based on a semiquantitative visual estimation of the hematopoietic and adipocytic components by hematopathologists, which does not provide quantitative information on other stromal compartments. In this study, we developed and validated MarrowQuant 2.0, an efficient, user-friendly digital hematopathology workflow integrated within QuPath software, which serves as BM quantifier for 5 mutually exclusive compartments (bone, hematopoietic, adipocytic, and interstitial/microvasculature areas and other) and derives the cellularity of human BM trephine biopsies. Instance segmentation of individual adipocytes is realized through the adaptation of the machine-learning-based algorithm StarDist. We calculated BM compartments and adipocyte size distributions of hematoxylin and eosin images obtained from 250 bone specimens, from control subjects and patients with acute myeloid leukemia or myelodysplastic syndrome, at diagnosis and follow-up, and measured the agreement of cellularity estimates by MarrowQuant 2.0 against visual scores from 4 hematopathologists. The algorithm was capable of robust BM compartment segmentation with an average mask accuracy of 86%, maximal for bone (99%), hematopoietic (92%), and adipocyte (98%) areas. MarrowQuant 2.0 cellularity score and hematopathologist estimations were highly correlated (R² = 0.92-0.98, intraclass correlation coefficient [ICC] = 0.98; interobserver ICC = 0.96). BM compartment segmentation quantitatively confirmed the reciprocity of the hematopoietic and adipocytic compartments. MarrowQuant 2.0 performance was additionally tested for cellularity assessment of specimens prospectively collected from clinical routine diagnosis. After special consideration for the choice of the cellularity equation in specimens with expanded stroma, performance was similar in this setting (R² = 0.86, n = 42). Thus, we conclude that these validation experiments establish MarrowQuant 2.0 as a reliable tool for BM cellularity assessment. We expect this workflow will serve as a clinical research tool to explore novel biomarkers related to BM stromal components and may contribute to further validation of future digitalized diagnostic hematopathology workstreams.

Clinicopathologic Characterization of Hypocellular Acute Myeloid Leukemia (AML) Showed Fewer Genetic Abnormalities Involving Cell Proliferation and NPM1 When Compared With Nonhypocellular AML

OBJECTIVES

Hypocellular acute myeloid leukemia (AML) is uncommon. Despite the prognostic and therapeutic importance of mutational analysis, the mutational landscape of hypocellular AML is not well understood.

METHODS

We identified 25 patients with hypocellular AML, and 141 patients with nonhypocellular AML were identified as a control group. We applied next-generation sequencing for the first time to profile this entity.

RESULTS

The hypocellular AML patients were older than those with nonhypocellular AML (P = .037). At diagnosis, hypocellular AML had lower leukocyte counts (P = .012), higher hemoglobin (P = .003), and lower blast counts in the peripheral blood (P < .001) and bone marrow (P = .003). Hypocellular AML was less likely to have mutations involving cell proliferation (P = .027) and NPM1 (P = .022) compared with nonhypocellular AML. Hypocellular AML showed a high incidence of spliceosomal mutations and myelodysplastic syndrome-defining chromosome abnormalities (65%), but the incidence was not significantly different from that in nonhypocellular AML. There was no significant survival difference between hypocellular and nonhypocellular AML.

CONCLUSIONS

To our knowledge, this study is the first to demonstrate hypocellular AML showed fewer genetic alterations involving cell proliferation and NPM1 when compared directly with nonhypocellular AML; this finding likely contributes to the low marrow cellularity in at least a portion of the patients with hypocellular AML.

Differential response to cytotoxic therapy explains treatment dynamics of acute myeloid leukaemia patients: insights from a mathematical modelling approach

Disease response and durability of remission are very heterogeneous in patients with acute myeloid leukaemia (AML). There is increasing evidence that the individual risk of early relapse can be predicted based on the initial treatment response. However, it is unclear how such a correlation is linked to functional aspects of AML progression and treatment. We suggest a mathematical model in which leukaemia-initiating cells and normal/healthy haematopoietic stem and progenitor cells reversibly change between an active state characterized by proliferation and chemosensitivity and a quiescent state, in which the cells do not divide, but are also insensitive to chemotherapy. Applying this model to 275 molecular time courses of nucleophosmin 1-mutated patients, we conclude that the differential chemosensitivity of the leukaemia-initiating cells together with the cells' intrinsic proliferative capacity is sufficient to reproduce both, early relapse as well as long-lasting remission. We can, furthermore, show that the model parameters associated with individual chemosensitivity and proliferative advantage of the leukaemic cells are closely linked to the patients' time to relapse, while a reliable prediction based on early response only is not possible based on the currently available data. Although we demonstrate with our approach, that the complete response data is sufficient to quantify the aggressiveness of the disease, further investigations are necessary to study how an intensive early sampling strategy may prospectively improve risk assessment and help to optimize individual treatments.

Proposed diagnostic criteria for classical chronic myelomonocytic leukemia (CMML), CMML variants and pre-CMML conditions

Chronic myelomonocytic leukemia (CMML) is a myeloid neoplasm characterized by dysplasia, abnormal production and accumulation of monocytic cells and an elevated risk of transforming into acute leukemia. Over the past two decades, our knowledge about the pathogenesis and molecular mechanisms in CMML has increased substantially. In parallel, better diagnostic criteria and therapeutic strategies have been developed. However, many questions remain regarding prognostication and optimal therapy. In addition, there is a need to define potential pre-phases of CMML and special CMML variants, and to separate these entities from each other and from conditions mimicking CMML. To address these unmet needs, an international consensus group met in a Working Conference in August 2018 and discussed open questions and issues around CMML, its variants, and pre-CMML conditions. The outcomes of this meeting are summarized herein and include diag nostic criteria and a proposed classification of pre-CMML conditions as well as refined minimal diagnostic criteria for classical CMML and special CMML variants, including oligomonocytic CMML and CMML associated with systemic mastocytosis. Moreover, we propose diagnostic standards and tools to distinguish between 'normal', pre-CMML and CMML entities. These criteria and standards should facilitate diagnostic and prognostic evaluations in daily practice and clinical studies in applied hematology.

Clinical, histopathological and molecular characterization of hypoplastic myelodysplastic syndrome

Diagnostic criteria for hypoplastic myelodysplasic syndrome (h-MDS) have not been clearly established, making the differential diagnosis from other bone marrow failure syndromes (BMF) challenging. In this study, we aimed to delineate clinical, histopathological, and molecular features of h-MDS, based on a large and well-annotated cohort of patients with bone marrow (BM) hypocellularity. The study included 534 consecutive adult patients with hypocellular BM (278 h-MDS and 136 aplastic anemia), and 727 with normo- or hypercellular MDS (n-MDS). Comparison of clinical features of patients with h-MDS as defined by BM cellularity ≤25% (n = 204) or reduced age-adjusted cellularity (n = 74) did not reveal significant differences. We developed a diagnostic score to discriminate h-MDS from non-malignant BMF based on histological and cytological variables with the highest specificity for MDS (h-score). The information from chromosomal abnormalities and somatic mutation patterns was then integrated into a cyto-histological/genetic score (hg-score). This score was able to segregate two groups of h-MDS with a significantly different risk of blast progression (P < 0.001). The integration of cyto-histological and genetic features in adult patients with hypocellular BM facilitated segregation into two distinct groups, one with clinical and genetic features highly consistent with myeloid neoplasm, and one with features more consistent with non-malignant BMF.

Trends in Bone Marrow Sampling and Core Biopsy Specimen Adequacy in the United States and Canada: A Multicenter Study

OBJECTIVES

To assess bone marrow (BM) sampling in academic medical centers.

METHODS

Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed.

RESULTS

BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent.

CONCLUSIONS

CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.

Proposed minimal diagnostic criteria for myelodysplastic syndromes (MDS) and potential pre-MDS conditions

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of myeloid neoplasms characterized by peripheral cytopenia, dysplasia, and a variable clinical course with about 30% risk to transform to secondary acute myeloid leukemia (AML). In the past 15 years, diagnostic evaluations, prognostication, and treatment of MDS have improved substantially. However, with the discovery of molecular markers and advent of novel targeted therapies, new challenges have emerged in the complex field of MDS. For example, MDS-related molecular lesions may be detectable in healthy individuals and increase in prevalence with age. Other patients exhibit persistent cytopenia of unknown etiology without dysplasia. Although these conditions are potential pre-phases of MDS they may also transform into other bone marrow neoplasms. Recently identified molecular, cytogenetic, and flow-based parameters may add in the delineation and prognostication of these conditions. However, no generally accepted integrated classification and no related criteria are as yet available. In an attempt to address this challenge, an international consensus group discussed these issues in a working conference in July 2016. The outcomes of this conference are summarized in the present article which includes criteria and a proposal for the classification of pre-MDS conditions as well as updated minimal diagnostic criteria of MDS. Moreover, we propose diagnostic standards to delineate between ´normal´, pre-MDS, and MDS. These standards and criteria should facilitate diagnostic and prognostic evaluations in clinical studies as well as in clinical practice.

Hypocellular acute myeloid leukemia treated with bone marrow transplantation

Hypocellular acute myeloid leukemia (AML) mainly occurs in elderly patients, and is extremely rare in childhood. There is still no established treatment for hypocellular AML. We report the case of an 11-year-old boy with hypocellular AML who was treated successfully with allogenic bone marrow transplantation (allo-BMT). He presented with fever, pallor and pancytopenia. Bone marrow aspiration and biopsy confirmed a diagnosis of hypocellular AML. Although low-dose cytarabine induced reduction of blasts, it did not lead to complete remission. He subsequently received myeloablative conditioning and allo-BMT. Graft-versus-host disease (GVHD) prophylaxis included short-course methotrexate and cyclosporine. Neutrophil engraftment (>5 × 10⁸ /L) and platelet recovery (>10 × 10¹⁰ /L) were achieved on days 13 and 27, respectively. He developed acute GVHD of the skin (grade 2), which responded well to treatment with prednisolone. He has remained in complete remission for 5 years since allo-BMT. We consider allo-BMT to be feasible for children with hypocellular AML.

Cellularity, characteristics of hematopoietic parameters and prognosis in myelodysplastic syndromes

BACKGROUND

Myelodysplastic syndromes (MDS) present with a normo- or hyperplastic bone marrow in most cases. We aimed at a characterization of patients with different types of cellularity.

METHODS

We assessed marrow cellularity both by histology and cytology in 1270 patients and analyzed hematologic, cytogenetic, and prognostic parameters accordingly.

RESULTS

The concordance of the assessment of cellularity differed dramatically between histology and cytology as only 36.5% were described as hypocellular by both methods (P < 0.0005) (hypocellular 16.4%, normocellular 23.3%, hypercellular 60.3%). There were no major differences with regard to hematopoietic insufficiency. The presence of fibrosis was associated to hypercellular bone marrow. Median survival differed from 38 months in hypocellular, 42 months in normocellular, and 25 months in hypercellular MDS (P < 0.0005). AML progression rates were 33% for hypercellular MDS after 2 yr, whereas hypo- and normocellular had a progression rate of 19% after 2 yr (P = 0.018). IPSS and IPSS-R were able to identify different risk groups within all three cellularity groups.

CONCLUSION

Based on our data, hypocellular patients obviously do not present as a separate entity, as there were no striking differences with regard to cytogenetics and WHO types. Assessment of cellularity should be performed by histopathology.

Diagnostic criteria to distinguish hypocellular acute myeloid leukemia from hypocellular myelodysplastic syndromes and aplastic anemia: recommendations for a standardized approach

Members of the French-American-British Cooperative Leukemia Working Group met to review cases of aplastic anemia, hypocellular myelodysplastic syndrome and hypocellular acute myeloid leukemia. Criteria were proposed and modified following three workshops. Additional input was obtained from another hematopathologist with a special interest in bone marrow histology and immunohistochemistry. Guidelines were recommended based on the workshop results as well as additional studies including selective immunohistochemistry, flow cytometry and cytogenetics.

Comparison of hypoplastic myelodysplastic syndrome (MDS) with normo-/hypercellular MDS by International Prognostic Scoring System, cytogenetic and genetic studies

The differences in clinical features and prognosis between hypoplastic myelodysplastic syndrome (h-MDS) and normo-/hypercellular MDS (NH-MDS) remain unsettled. In this study, the characteristics of 37 h-MDS patients and 152 NH-MDS patients were compared. Peripheral-blood white blood cell counts and bone marrow blast percentage were lower in h-MDS patients than in NH-MDS patients (P=0.012 and 0.016, respectively). Refractory anemia (RA) was predominant (56.8%) in h-MDS, whereas RA with excess of blast (RAEB) was most common (44.7%) in NH-MDS. Chromosomal abnormalities -7/7q- occurred less frequently in h-MDS patients than in NH-MDS patients (0 vs 18.3%, P=0.022). There was no significant difference in the prevalence of mutations of RAS, AML1, JAK2, PTPN11, FLT3/ITD, and hypermethylation of SOCS1 and SHP1 between these two groups. International Prognostic Scoring System (IPSS) was ideal for predicting prognoses in h-MDS patients (P=0.002). In low- or intermediate-1 (Int-1)-risk MDS patients, h-MDS patients had a superior survival than NH-MDS patients (P=0.01). In conclusion, distinct from NH-MDS, h-MDS patients have different patterns of hemogram, distribution of French-American-British subtypes, cytogenetic changes and prognoses. IPSS is applicable in h-MDS as in NH-MDS. In patients with low- or Int-1-risk MDS, h-MDS patients have a better prognosis than NH-MDS patients.

Hypocellularity in myelodysplastic syndrome is an independent factor which predicts a favorable outcome

Hypocellular myelodysplastic syndrome (MDS) represents only a small portion of MDS, of which, the clinical significance has not been well-defined. By using currently accepted age-adjusted criteria to define hypocellularity as <30% in patients <70 years old, and <20% in >70 years old, we identified 163 (15.5%) hypocelluar MDS from 1049 consecutive adult MDS patients over an 11-year period (1995-2006). Compared to normal/hypercellular MDS, hypocellular MDS patients were younger (p<0.01), less anemic (p=0.02), but more neutropenic (p<0.001) and thrombocytopenic (p=0.05), and had a comparable cytogenetic risk group distribution (p=0.09) and international prognostic scores (IPSS, p=0.13). With a median follow-up of 52 months, hypocellular MDS showed a favorable overall survival (56 months versus 28 months, log-rank p<0.0001) over normal/hypocellular MDS, and this survival preference was also demonstrated in all IPSS groups and cytogenetic risk groups, and was independent of all other risk factors (Cox regression test, p=0.01). In conclusion, our study demonstrated that hypocellular MDS has characteristic clinicopathologic features, and bone marrow hypocellularity in MDS is an independent factor which predicts a favorable outcome.

Definitions and standards in the diagnosis and treatment of the myelodysplastic syndromes: Consensus statements and report from a working conference

The classification, scoring systems, and response criteria for myelodysplastic syndromes (MDS) have recently been updated and have become widely accepted. In addition, several new effective targeted drugs for patients with MDS have been developed. The current article provides a summary of updated and newly proposed markers, criteria, and standards in MDS, with special reference to the diagnostic interface and refinements in evaluations and scoring. Concerning the diagnostic interface, minimal diagnostic criteria for MDS are proposed, and for patients with unexplained cytopenia who do not fulfill these criteria, the term 'idiopathic cytopenia of uncertain significance' (ICUS) is suggested. In addition, new diagnostic and prognostic parameters, histopathologic and immunologic determinants, proposed refinements in scoring systems, and new therapeutic approaches are discussed. Respective algorithms and recommendations should facilitate diagnostic and prognostic evaluations in MDS, selection of patients for therapies, and the conduct of clinical trials.

The myelodysplastic syndromes: diagnosis and treatment

The myelodysplastic syndromes (MDSs) are common, acquired, clinically challenging hematologic conditions that are characterized by bone marrow failure and a risk of progression to acute leukemia. These disorders can arise de novo, especially in elderly patients or, less often, as a consequence of prior chemotherapy or radiotherapy for an unrelated disease. The MDS classification systems were revised recently and updated. These refined classification and prognostic schemes help stratify patients by their risk of leukemia progression and death; this knowledge can help clinicians select appropriate therapy. Although many treatments for MDS have been proposed and evaluated, at present, only hematopoietic stem cell transplantation offers any real hope for cure, and no available therapy beyond general supportive care offers benefit to more than a minority of patients. However, recent clinical trials enrolling patients with MDS have reported encouraging results with use of newer drugs, including lenalidomide, decitabine, and darbepoetin alfa. Other exciting treatment regimens are being tested. Here, we present a contemporary, practical clinical approach to the diagnosis and risk-stratified treatment of MDS. We review when to suspect MDS, detail how to evaluate patients who may have a form of the condition, explain key features of treatments that are currently available in the United States, and summarize a general, common-sense therapeutic approach to patients with MDS.

Hypocellular myelodysplastic syndromes: clinical and biological significance

The article is concerned with incidence, clinical features, response to therapy, and prognosis of patients with hypocellular myelodysplastic syndromes. Bone marrow (BM) cellularity <30% (or <20% in patients >70 yr) was found in 24 of 236 (10.2%) trephine biopsies. Median age was 61 yr, with significant male predominance (M/F=3.0) At diagnosis, median hemoglobin was 83 g/L, median platelet and neutrofil counts were 31x109/L and 1.2x109/L, respectively. According to FAB classification, 17 patients had RA, 6 had RAEB, and only 1 had RAEB-t. Beside marrow hypoplasia, the most prominent PH finding was megakaryocyte hypoplasia and dysplasia, found in two-thirds of cases, each. Comparison between hypocellular and normo/hypercellular MDS cases regarding clinicopathological features showed younger age, more severe cytopenia, less blood and BM blast infiltration, MK hypoproliferation, and more pronounced stromal reactions in former cases. Karyotypic abnormalities were present in 12.5% hypocellular cases, in contrast to 44.6% normo/hypercellular cases (p=0.0025). Eleven patients were treated with supportive therapy alone, six with danazol or androgens, six with immunosuppressive therapy, and one with LDARAC. However, complete or partial response was achieved in only four patients treated with danazol or androgens. None of the patients developed leukemia. Eleven patients died, so marrow insufficiency was the main cause of death. Median survival was 33 mo for hypocellular MDS, and 19 mo for normo/hypercellular MDS (p=0.09). The results confirm the existence of hypocellular variant of MDS, which seems to have better prognosis than those patients with normo/hypercellular disease.

Familial myelodysplastic syndrome with early age of onset

A family is described in which three members, the propositus, his brother, and son, developed a myelodysplastic syndrome (MDS) at the ages of 52, 35, and 25, respectively. A fourth member, the paternal uncle of the propositus, was diagnosed with chronic lymphocytic leukemia. Two of the three affected Individuals had megaloblastoid marrows with recognizable bone marrow cytogenetic abnormalities and progressive, nonleukemic bone marrow failure. The propositus was unresponsive to G-CSF and eventually died of sepsis. The second affected family member died of bone marrow transplant complications. The third affected family member underwent bone marrow transplantation and is showing signs of graft survival despite minor complications. The affected members of this pedigree appear to represent a continuum in severity of disease and, therefore, pathogenesis. The pattern of inheritance and clinical progression of the disease suggest a genetic defect which may predispose individuals to the development of MDS.

Practical aspects in the diagnosis and management of aplastic anemia

Aplastic anemia may result from several pathogenic mechanisms, the most common is idiopathic. The current definitive treatments for aplastic anemia are bone marrow transplantation (BMT) or immunosuppressive (IS) therapy. The benefits of each are comparable. However, certain subsets of patients derive superior benefit from one or the other. Bone marrow transplantation is the initial treatment of choice for young patients (< 20 years old). It results in the complete reconstitution of hematopoiesis, whereas autologous hematopoietic remissions after IS therapy are more susceptible to relapse. Survival rates after BMT, in patients between the ages of 20 and 40, are comparable to those reported for IS therapy. Better survival rates after BMT have been achieved with improved conditioning regimens and graft-versus-host disease prophylaxis. For patients older than 40, the treatment of choice is IS. Long-term complications of IS therapy include recurrence and development of clonal myeloid disorders. Long-term complications after BMT include graft-versus-host disease and secondary neoplasms. The IS regimen includes the combination of antithymocyte globulin and cyclosporin A. The addition of growth factor to the IS regimen seems promising; however, their use on their own is not recommended. Androgens have been shown to be inferior in the treatment of aplastic anemia. The role of BMT from an unrelated donor is being investigated.

Diagnostic criteria for hypocellular acute leukemia: a clinical entity distinct from overt acute leukemia and myelodysplastic syndrome

In order to establish diagnostic criteria for hypocellular acute leukemia (HL), we have reviewed 32 cases selected on the basis of hypothetical 40% or less cellularity, by focusing on morphology, immunophenotype, karyotype and response to low dose Ara-C (LDAC) regimen and compared them with 40 cases of myelodysplastic syndrome (MDS) and 66 cases of overt acute myeloid leukemia (AML). The onset age ranged from 44 to 75 years (median 67 years). Bone marrow (BM) cellularity ranged from 12.4 to 39.8% (mean 29.8%) in HL, being significantly lower than in MDS (mean 80.7%) or AML (mean 86.4%) (P < 0.001). All reviewed cases characteristically showed smoldering clinical course, bi- or pancytopenia with rare leukemic blasts in the peripheral blood (PB), proliferation of type I leukemic blasts in the BM and markedly reduced background hematopoietic cells with some dysplastic changes in 12/32 cases (37.50/6). Blast percentage (blast %) in the BM ranged from 38.2 to 93.7% (mean 57.3%) in all nucleated cells (ANC). Although a considerable number of cases had blasts with negative or very low myeloperoxidase activity, immunophenotyping revealed that the leukemic blasts in HL had only myeloid markers. Karyotyping revealed non-random chromosome abnormalities in 30% of cases analyzed, which were considerably different from those seen in MDS. With LDAC regimen, a significantly higher CR rate (13/20 cases: 65.0%) was gained in HL than in RAEB/RAEB-t (0%) and overt AML in the elderly cases (27.3%) (P < 0.05). In CR, most cases showed recovery to normocellular BM with an apparent normalization of PB parameters. However, 12 CR cases relapsed 4-12 months later; most of which again showed hypocellular BM. These results indicate that HL is a distinct subtype of AML characterized by slow but distinct proliferation of immature myeloid blasts and by unique hematological features distinct from MDS or overt AML in the elderly. We propose the following diagnostic criteria: (1) pancytopenia with rare appearance of blasts in PB; (2) less than 40% BM hypocellularity; (3) more than 30% blasts in BM-ANC; and (4) myeloid phenotypes of leukemic blasts by MPO staining and/or immunophenotyping.

Hypocellular myelodysplastic syndromes (MDS): new proposals

To determine whether hypocellular MDS differs from normo/hypercellular MDS, we attempted to identify hypocellular MDS cases either by correcting the bone marrow (BM) cellularity by age (28 patients) or by using a single arbitrary value of BM cellularity (25 patients) and compared these two groups of hypocellular cases to the normo/hypercellular MDS cases (72 patients). 18 patients were common to both hypocellular groups. Patients with hypocellular MDS in both of these selected groups have similar features with regard to age and sex distribution, peripheral blood and bone marrow parameters, FAB subtypes, karyotypes, leukaemic transformation, and survival. However, the median age of patients in < 30% BM cellularity group was higher than those patients in the age-corrected group (69 years v 62 years). The selection of < 30% cellularity excluded 10 cases in the age group < 70 years but included another seven patients in the age group of > 70 years. However, correction of BM cellularity by age revealed that those included patients (selected for < 30% cellularity) who had normocellular BM by their age. Therefore we recommend the age-correcting grouping to ensure comparable series for comparison, for response to treatment, and survival. Finally, BM cellularity does not appear to be an important factor on prognosis in MDS, because patients with hypocellular MDS in both selected groups have similar prognosis to those with normo/hypercellular MDS patients.