A new disease categorization of low-grade myelodysplastic syndromes based on the expression of cytopenia and dysplasia in one versus more than one lineage improves on the WHO classification

Morphologic Characteristics of Myelodysplastic Syndromes

Morphologic characterization remains a cornerstone in the diagnosis and classification of myelodysplastic syndromes (MDS) in the updated International Consensus Classification (ICC) and 5th edition World Health Organization Classification of Myeloid Neoplasms (Arber, Orazi, & Hasserjian, 2022; Khoury & Solary, 2022). The presence of dysplasia is one of the key diagnostic criteria required for establishing a diagnosis of MDS, and the percentage of myeloblasts in the blood and bone marrow impacts both disease classification and prognostication. Morphologic features also aid in distinguishing MDS from a myriad of other myeloid neoplasms and non-neoplastic mimics. Additional key morphologic features that should be recorded in any MDS case are the bone marrow cellularity and the degree of reticulin fibrosis. In this review, the morphologic assessment of the bone marrow biopsy, bone marrow aspirate, and peripheral blood smear as it pertains to the diagnosis and up-to-date classification of MDS will be described. The implications of the findings on classification and prognosis will also be discussed.

The International Consensus Classification of myelodysplastic syndromes and related entities

The International Consensus Classification (ICC) of myeloid neoplasms and acute leukemia has updated the classification of myelodysplastic syndromes (MDSs) and placed MDS in a broader group of clonal cytopenias that includes clonal cytopenia of undetermined significance (CCUS) and related entities. Although subject to some interobserver variability and lack of specificity, morphologic dysplasia remains the main feature that distinguishes MDS from other clonal cytopenias and defines MDS as a hematologic malignancy. The ICC has introduced some changes in the definition of MDS whereby some cases categorized as MDS based on cytogenetic abnormalities are now classified as CCUS, while SF3B1 and multi-hit TP53 mutations are now considered to be MDS-defining in a cytopenic patient. The ICC has also recognized several cytogenetic and molecular abnormalities that reclassify some cases of MDS with excess blasts as acute myeloid leukemia (AML) and has introduced a new MDS/AML entity that encompasses cases with 10-19% blasts that lie on the continuum between MDS and AML. Two new genetically defined categories of MDS have been introduced: MDS with mutated SF3B1 and MDS with mutated TP53, the latter requiring bi-allelic aberrations in the TP53 gene. The entity MDS, unclassifiable has been eliminated. These changes have resulted in an overall simplification of the MDS classification scheme from 8 separate entities (including 1 that was genetically defined) in the revised 4th edition WHO classification to 7 separate entities (including 3 that are genetically defined) in the ICC.

Erythroid nuclear dysplasia is associated with inferior outcomes for patients with myelodysplastic syndrome undergoing allogeneic hematopoietic cell transplantation

Disease burden prior to hematopoietic cell transplantation (HCT) is difficult to assess in myelodysplastic syndrome (MDS), particularly in patients without excess blasts. We assessed whether morphologic dysplasia at the time of transplant can be a metric of disease burden that is associated with post-transplant outcomes in MDS patients. We identified 84 MDS patients undergoing allogeneic HCT at our institution between 2010 and 2017 who received a bone marrow evaluation immediately prior to HCT. Dysplasia was independently determined by two hematopathologists blinded to existing pathology reports. Erythroid nuclear dysplasia, but not megakaryocytic or myeloid, was associated with post-HCT outcomes. Presence compared to absence of erythroid nuclear dysplasia was associated with lower 2-year progression-free survival (PFS; 34 % vs 62 %, p = 0.0495) and 2-year overall survival (OS; 34 % vs 62 %, p = 0.042). In a multivariate analysis including age, IPSS-R at the time of transplant, pre-HCT therapy, and donor type as covariates, erythroid nuclear dysplasia remained associated with lower PFS (HR 2.6, p = 0.036) and OS (HR 2.7, p = 0.028). Dysplasia assessment prior to transplant may serve as an estimate of disease burden in MDS and identify high-risk patients who merit additional therapies pre- or post-transplant.

Etiology and clinico-hematological profile of pancytopenia: experience of a Mexican Tertiary Care Center and review of the literature

BACKGROUND

Pancytopenia is a frequent entity in clinical practice as a feature of a myriad of conditions, ranging from benign to malignant diseases. Since the cause of pancytopenia depends on environmental factors, it is important to know the common etiologies of pancytopenia, however, few studies address this.

OBJECTIVES

To identify the etiology of pancytopenia in our population and compare them with what is reported elsewhere.

METHODS

We conducted an observational study of patients with pancytopenia in a Mexican Tertiary Care Center. Clinical, hematological and bone marrow studies were performed in all patients.

RESULTS

Of 109 cases included, the mean age at diagnosis was 49.4 years, with a slightly higher female incidence (53.2%). The most common causes of pancytopenia were: MDS (20.2%), megaloblastic anemia (18.3%) and AML (12.8%).

DISCUSSION

We found a complex picture of pancytopenia in Mexico and compared it with what is reported elsewhere in the literature.

CONCLUSION

The sociocultural context in which the patients develop helps narrowing the possible etiology of pancytopenia, and therefore hasten the diagnostic process. Of all the studies available, bone marrow aspiration seems the most useful.

PAS positivity of erythroid precursor cells is associated with a poor prognosis in newly diagnosed myelodysplastic syndrome patients

Myelodysplastic syndrome (MDS) is a group of clonal stem cell disorders characterized by hematopoietic insufficiency. The accurate risk stratification of patients with MDS is essential for selection of appropriate therapies. We herein conducted a retrospective cohort study to examine the prognostic value of periodic acid-Schiff (PAS) reaction-positive erythroblasts in MDS patients. We examined the PAS positivity of the bone marrow erythroblasts of 144 patients newly diagnosed with MDS; 26 (18.1%) of them had PAS-positive erythroblasts, whereas 118 (81.9%) did not. The PAS-positive group showed significantly poorer karyotypes as defined in the revised International Prognostic Scoring System (IPSS-R) and higher scores in age-adjusted IPSS-R (IPSS-RA) than the PAS-negative group. Overall survival (OS) and leukemia-free survival (LFS) were also significantly shorter in the PAS-positive group than in the PAS-negative group. Similar results were obtained when only high- and very high risk groups were analyzed using IPSS-RA. This retrospective study suggested that the PAS positivity of erythroblasts is an additional prognostic factor combined with other risk scores for OS and LFS in MDS, and our results may contribute to improved clinical decision-making and rapid risk stratification.

Discriminating myelodysplastic syndrome and other myeloid malignancies from non-clonal disorders by multiparametric analysis of automated cell data

BACKGROUND

We investigated the usefulness of novel complete blood count (CBC) data for discriminating myeloid malignancies from non-clonal CBC abnormalities.

METHODS

Data were obtained during routine CBC tests of 119 samples from 37 myelodysplastic syndrome (MDS) patients, 92 samples from 45 myeloproliferative neoplasm (MPN) patients, and 15 samples from 11 chronic myelogenous leukemia (CML) patients using a DxH800 (Beckman Coulter). Data obtained from patients with hypocellular bone marrow and from those with other non-clonal diseases with CBC abnormalities were included in the comparisons.

RESULTS

For cell population data of neutrophils, the means of median, upper median, lower median, and low angle light scatters were significantly lower in MDS patients than in patients without hematological malignancies. Low hemoglobin density (LHD) did not significantly differ between the MDS and non-clonal cytopenia patients, but it was significantly higher in the MPN and CML patients. We selected 13 parameters and scored the MDS diagnosis using cut-off values obtained from receiver operating characteristic (ROC) curve analysis. Using a score > 9, MDS was distinguished from non-clonal cytopenia with a sensitivity of 92.4% and a specificity of 85.4%.

CONCLUSIONS

Multiparametric analyses of new automated parameters are useful for discriminating MDS from non-clonal cytopenia.

Changes in the World Health Organization 2016 classification of myeloid neoplasms everyone should know

PURPOSE OF REVIEW

This review highlights the main changes in the revised 2016 WHO classification of myeloid neoplasms (published in 2017) that impact diagnosis and ultimately impact management of patients with these diseases.

RECENT FINDINGS

The revision was based on data accumulated since the 2008 WHO classification, much of which relate to new molecular genetic information about these neoplasms. This massive recent influx of data concerning the significance of pathogenic mutations has affected all myeloid neoplasm categories. The new information has been incorporated as part of the diagnostic criteria of many diseases and has led to the creation of new provisional entities defined by genetic features. Germline mutations that predispose to myeloid neoplasms are also emerging as important findings that impact disease classification.

SUMMARY

The growing body of genetic data have not only altered the classification of myeloid neoplasms, but are also impacting patient management. Genetically-defined disease categories have characteristic prognoses and predicted clinical behavior. Some mutations are associated with responsiveness to certain therapies, including those that target relevant oncogenes. The disease categories in the new classification facilitate the application of risk-adapted therapy based on the most recently available data.

Myelodysplastic Syndrome, Unclassifiable (MDS-U) With 1% Blasts Is a Distinct Subgroup of MDS-U With a Poor Prognosis

OBJECTIVES

Three situations qualify as myelodysplastic syndrome, unclassifiable (MDS-U): (1) refractory cytopenia with dysplasia and 1% blasts in peripheral blood (BL), (2) pancytopenia with unilineage dysplasia (Pan), and (3) persistent cytopenia, less than 5% bone marrow blasts, and less than 10% dysplastic cells and presence of MDS-defining cytogenetic abnormalities (CG). We compared the clinicopathologic features and mutational profiles for these three groups.

METHODS

MDS-U cases were reviewed at four major academic institutions. Targeted next-generation sequencing for genes implicated in myeloid neoplasms was performed in a subset of cases.

RESULTS

Twenty-seven patients were identified (six MDS-U BL, 13 MDS-U Pan, and eight MDS-U CG). Clonal cytogenetic abnormalities were found in six of six, seven of 13, and eight of eight cases in MDS-U BL, Pan, and CG, respectively (P > .05). Overall, four of six patients with MDS-U BL progressed to acute myeloid leukemia; no MDS-U Pan or CG patients did. The rates of progression-free survival and mortality (overall survival) were significantly higher in MDS-U BL compared with Pan and CG (P < .001 for both).

CONCLUSIONS

We find that MDS-U BL is a distinct subset of MDS-U with a poor prognosis, while MDS-U Pan and CG are relatively indolent. Evaluation of peripheral blood smears in patients with MDS is essential for accurate classification and prognosis.

The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia

The World Health Organization (WHO) classification of tumors of the hematopoietic and lymphoid tissues was last updated in 2008. Since then, there have been numerous advances in the identification of unique biomarkers associated with some myeloid neoplasms and acute leukemias, largely derived from gene expression analysis and next-generation sequencing that can significantly improve the diagnostic criteria as well as the prognostic relevance of entities currently included in the WHO classification and that also suggest new entities that should be added. Therefore, there is a clear need for a revision to the current classification. The revisions to the categories of myeloid neoplasms and acute leukemia will be published in a monograph in 2016 and reflect a consensus of opinion of hematopathologists, hematologists, oncologists, and geneticists. The 2016 edition represents a revision of the prior classification rather than an entirely new classification and attempts to incorporate new clinical, prognostic, morphologic, immunophenotypic, and genetic data that have emerged since the last edition. The major changes in the classification and their rationale are presented here.

Reproducibility and prognostic significance of morphologic dysplasia in de novo acute myeloid leukemia

The 2008 WHO classification of acute myeloid leukemia includes a category of acute myeloid leukemia with myelodysplasia-related changes; however, the significance of multilineage dysplasia alone is controversial and its reproducibility has not been evaluated in acute myeloid leukemia. We performed an in-depth analysis of morphologic dysplasia in 159 de novo acute myeloid leukemia cases lacking myelodysplasia-related cytogenetic abnormalities. Using the 2008 WHO criteria, there were 89 acute myeloid leukemia-not otherwise specified (56%) and 43 acute myeloid leukemia with myelodysplasia-related changes (27%), while 27 cases were ambiguous as to myelodysplasia-related changes status due to limited maturing cells (acute myeloid leukemia-not evaluable, 17%). On multivariable analysis, neither acute myeloid leukemia with myelodysplasia-related changes nor acute myeloid leukemia-not evaluable showed significantly different event-free survival compared with acute myeloid leukemia-not otherwise specified in the 137 patients treated with induction chemotherapy. When individual dysplastic features were analyzed, only micromegakaryocytes and hypogranulated myeloid cells emerged as factors significantly associated with shorter event-free survival in a multivariable analysis that included the other significant covariates of age, white blood count, platelet count, abnormal karyotype and stem-cell transplantation. Our findings indicate that the current 2008 WHO definition of multilineage dysplasia in acute myeloid leukemia in its current form is not optimal, and that the use of a more restricted definition of morphologic dysplasia results in more relevant risk stratification that is independent of other conventional prognostic factors.

Importance of classical morphology in the diagnosis of myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are hematopoietic stem cell disorders characterized by dysplastic, ineffective, clonal and neoplastic hematopoiesis. MDS represent a complex hematological problem: differences in disease presentation, progression and outcome have necessitated the use of classification systems to improve diagnosis, prognostication, and treatment selection. However, since a single biological or genetic reliable diagnostic marker has not yet been discovered for MDS, quantitative and qualitative dysplastic morphological alterations of bone marrow precursors and peripheral blood cells are still fundamental for diagnostic classification. In this paper, World Health Organization (WHO) classification refinements and current minimal diagnostic criteria proposed by expert panels are highlighted, and related problematic issues are discussed. The recommendations should facilitate diagnostic and prognostic evaluations in MDS and selection of patients for new effective targeted therapies. Although, in the future, morphology should be supplemented with new molecular techniques, the morphological approach, at least for the moment, is still the cornerstone for the diagnosis and classification of these disorders.

Refractory thrombocytopenia and neutropenia: a diagnostic challenge

The 2008 WHO classification identified refractory cytopenia with unilineage dysplasia (RCUD) as a composite entity encompassing refractory anemia, refractory thrombocytopenia (RT), and refractory neutropenia (RN), characterized by 10% or more dysplastic cells in the bone marrow respective lineage. The diagnosis of RT and RN is complicated by several factors. Diagnosing RT first requires exclusion of familial thrombocytopenia, chronic auto-immune thrombocytopenia, concomitant medications, viral infections, or hypersplenism. Diagnosis of RN should also be made after ruling out differential diagnoses such as ethnic or familial neutropenia, as well as acquired, drug-induced, infection-related or malignancy-related neutropenia. An accurate quantification of dysplasia should be performed in order to distinguish RT or RN from the provisional entity named idiopathic cytopenia of unknown significance (ICUS). Cytogenetic analysis, and possibly in the future somatic mutation analysis (of genes most frequently mutated in MDS), and flow cytometry analysis aberrant antigen expression on myeloid cells may help in this differential diagnosis. Importantly, we and others found that, while isolated neutropenia and thrombocytopenia are not rare in MDS, those patients can generally be classified (according to WHO 2008 classification) as refractory cytopenia with multilineage dysplasia or refractory anemia with excess blasts, while RT and RN (according to WHO 2008) are quite rare. These results suggest in particular that identification of RT and RN as distinct entities could be reconsidered in future WHO classification updates.

A case of myelodysplastic syndrome with marked eosinophilia showing favorable prognosis

Myelodysplastic syndrome (MDS) with eosinophilia is a rare condition and has yet to be classified under the 2008 World Health Organization classification. However, reports have described the prognostic significance of chronic persistent eosinophilia in MDS. Here, we report a case of a 67-year-old woman who was admitted to the hospital in July 2007 with generalized weakness, dizziness, and dyspnea on exertion persisting for 5 years. In the initial investigation, eosinophilia (22.1%) in peripheral blood and an increased proportion of eosinophils (5.6%) in normocellular bone marrow with dysplastic megakaryocytes and erythroid cells were noted. Eosinophilia was continuously detected during follow-up over 3 years. In a second bone marrow examination in August 2010, hypercellular bone marrow with similar features was observed. These findings led to the diagnosis of MDS with chronic persistent eosinophilia. To increase awareness of the prognostic significance of MDS with chronic eosinophilia, here we report a slow-progressing case of MDS with chronic persistent eosinophilia lasting over 6 years.

Review of therapeutic options and the management of patients with myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a poorly understood group of disorders caused by one or more genetic aberrations in the bone marrow-derived cell line responsible for hematopoiesis. Recent advances in genetic medicine have offered new insights into the epigenesis as well as the prognosis of MDS, but have not resulted in new or improved curative treatment options. Bone marrow transplantation, introduced before the advent of genetic medicine, is still the only potential cure. Advances in other medical and pharmaceutical areas have broadened the scope of supportive care and disease-modifying therapies, and treating physicians now have a broad range of disease management options depending on a patient's likely prognosis. There is now clear evidence that appropriate supportive care and therapeutic intervention can improve progression-free and overall survival of MDS patients.

Longitudinal bone marrow evaluations for myelodysplasia in patients with myeloma before and after treatment with lenalidomide

Lenalidomide (LEN) treatment in multiple myeloma (MM) results in a superior outcome. However, there is concern for increased myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) associated with LEN. Thus, bone marrow morphology and cytogenetics studies from 40 patients were evaluated for early signs of MDS prior to therapy, during therapy and at follow-up. Newly diagnosed patients with MM treated with LEN and dexamethasone (LD) alone or followed by autologous stem cell transplant (LD/ASCT), or patients with relapsed/refractory MM treated with LEN, bendamustine and dexamethasone (BLD) were included. One patient developed MDS. Baseline prevalence of mild morphologic myelodysplasia was highest in pretreated patients with MM (BLD, 71%), but was also seen in newly diagnosed patients (LD and LD/ASCT, 17%). The prevalence of myelodysplasia did not increase over time. Thus, this study did not reveal rapidly emerging MDS in 39 of 40 patients with MM treated with LEN. The development of MDS in one patient suggests that longer follow-up is needed for all.

Diagnosis of myelodysplastic syndromes in cytopenic patients

Sustained clinical cytopenia is a frequent laboratory finding in ambulatory and hospitalized patients. For pathologists and hematopathologists who examine the bone marrow (BM), a diagnosis of cytopenia secondary to an infiltrative BM process or acute leukemia can be readily established based on morphologic evaluation and flow cytometry immunophenotyping. However, it can be more challenging to establish a diagnosis of myelodysplastic syndrome (MDS). In this article, the practical approaches for establishing or excluding a diagnosis of MDS (especially low-grade MDS) in patients with clinical cytopenia are discussed along with the current diagnostic recommendations provided by the World Health Organization and the International Working Group for MDS.

Erythroid proliferations in myeloid neoplasms

Prominent erythroid proliferations (in which erythroid elements comprise ≥50% of total bone marrow cells) can be seen in various hematopoietic stem cell neoplasms. The myeloproliferative neoplasm polycythemia vera exhibits effective, overexuberant erythropoiesis resulting in an increased red blood cell mass; in contrast, most other diseases characterized by erythroid predominance exhibit ineffective hemopoiesis. The latter include acute erythroid leukemia (erythroid-myeloid and pure erythroid leukemia subtypes) as well as some cases of myelodysplastic syndromes, acute myeloid leukemia with myelodysplasia-related changes, and therapy-related myeloid neoplasms. Some nonneoplastic reactive conditions may also manifest a striking bone marrow erythroid predominance. In this article, we review the literature relevant to this group of diseases for a better understanding of their clinicopathologic features and surrounding controversies. We also examine the position of neoplastic erythroid proliferations in the current 2008 World Health Organization Classification of Myeloid Neoplasms and provide recommendations as to how to approach the differential diagnosis of this group of diseases.

Altered immunophenotypic features of peripheral blood platelets in myelodysplastic syndromes

BACKGROUND

Multiparameter flow cytometric analysis of bone marrow and peripheral blood cells has proven to be of help in the diagnostic workup of myelodysplastic syndromes. However, the usefulness of flow cytometry for the detection of megakaryocytic and platelet dysplasia has not yet been investigated. The aim of this pilot study was to evaluate by flow cytometry the diagnostic and prognostic value of platelet dysplasia in myelodysplastic syndromes.

DESIGN AND METHODS

We investigated the pattern of expression of distinct surface glycoproteins on peripheral blood platelets from a series of 44 myelodysplastic syndrome patients, 20 healthy subjects and 19 patients with platelet alterations associated to disease conditions other than myelodysplastic syndromes. Quantitative expression of CD31, CD34, CD36, CD41a, CD41b, CD42a, CD42b and CD61 glycoproteins together with the PAC-1, CD62-P, fibrinogen and CD63 platelet activation-associated markers and platelet light scatter properties were systematically evaluated.

RESULTS

Overall, flow cytometry identified multiple immunophenotypic abnormalities on platelets of myelodysplastic syndrome patients, including altered light scatter characteristics, over-and under expression of specific platelet glycoproteins and asynchronous expression of CD34; decreased expression of CD36 (n = 5), CD42a (n = 1) and CD61 (n = 2), together with reactivity for CD34 (n = 1) were only observed among myelodysplastic syndrome cases, while other alterations were also found in other platelet disorders. Based on the overall platelet alterations detected for each patient, an immunophenotypic score was built which identified a subgroup of myelodysplastic syndrome patients with a high rate of moderate to severe alterations (score>1.5; n = 16) who more frequently showed thrombocytopenia, megakaryocytic dysplasia and high-risk disease, together with a shorter overall survival.

CONCLUSIONS

Our results show the presence of altered phenotypes by flow cytometry on platelets from around half of the myelodysplastic syndrome patients studied. If confirmed in larger series of patients, these findings may help refine the diagnostic and prognostic assessment of this group of disorders.

Assessment of dysplastic hematopoiesis: lessons from healthy bone marrow donors

BACKGROUND

According to WHO 2008 guidelines, the required percentage of cells manifesting dysplasia in the bone marrow to qualify as significant is 10% or over in one or more hematopoietic cell lineages, but this threshold is controversial. No 'normal' values have been established. Therefore, we investigated dyshematopoiesis in bone marrow aspirate squash preparations of 120 healthy bone marrow donors.

DESIGN AND METHODS

Bone marrow squash slides of 120 healthy unrelated bone marrow donors were examined independently by 4 experienced morphologists. Samples were taken from the first aspiration during the harvest. Bone marrow preparation and assessment were performed according to WHO recommendations and ICSH guidelines.

RESULTS

More than 10% dysmyelopoiesis could be detected in 46% of bone marrow aspirate squash preparations with 26% in 2 or more cell lineages and 7% in 3 cell lineages in healthy bone marrow donors. Donors under the age of 30 years exhibited more dysgranulopoietic changes and dysmegakaryopoietic changes (P<0.001) compared to the older donors. Female donors showed more dysgranulopoietic changes than male donors (P = 0.025). The concordance rate between the 4 investigators was modest in dysgranulopoiesis but poor in dyserythropoiesis and dysmegakaryopoiesis.

CONCLUSIONS

The poor reliability of the 10% cut off was partly related to the proximity of the current criteria to the observed cut-off mean values of the normal population. These findings question the current WHO threshold of the 10% or over necessary for the percentage of cells manifesting dysplasia to be considered significant, and suggest that either a higher threshold would be more appropriate or different thresholds should be set for each lineage.

Diagnosis of Myelodysplastic Syndromes in Cytopenic Patients

Sustained clinical cytopenia is a frequent laboratory finding in ambulatory and hospitalized patients. For pathologists and hematopathologists who examine the bone marrow (BM), a diagnosis of cytopenia secondary to an infiltrative BM process or acute leukemia can be readily established based on morphologic evaluation and flow cytometry immunophenotyping. However, it can be more challenging to establish a diagnosis of myelodysplastic syndrome (MDS). In this article, the practical approaches for establishing or excluding a diagnosis of MDS (especially low-grade MDS) in patients with clinical cytopenia are discussed along with the current diagnostic recommendations provided by the World Health Organization and the International Working Group for MDS.

Bone marrow cells from myelodysplastic syndromes show altered immunophenotypic profiles that may contribute to the diagnosis and prognostic stratification of the disease: a pilot study on a series of 56 patients

A heterogeneous spectrum of immunophenotypic abnormalities have been reported in myelodysplastic syndromes (MDS). However, most studies are restricted to the analysis of CD34(+) cells and/or other major subsets of CD34(-) cells, frequently not exploring the diagnostic and prognostic impact of immunophenotyping.

METHODS

We propose for the first time an immunophenotypic score (IS) based on the altered distribution and immunophenotypic features of maturing/mature compartments of bone marrow (BM) hematopoietic cells in 56 patients with MDS that could contribute to a refined diagnosis and prognostic evaluation of the disease.

RESULTS

Although MDS-associated phenotypes were detected in reactive BM, the overall immunophenotypic profile of BM cells allowed an efficient discrimination between MDS and both normal and reactive BM, once the number and degree of severity of the abnormalities detected per patient were simultaneously considered in the proposed IS. Interestingly, increasingly higher IS were found among patients with MDS showing adverse prognostic factors and in low- versus high-grade cases. The most informative prognostic factors included the number of CD34(+) cells, presence of aberrant CD34(-)/CD117(+) precursors, decreased mature neutrophils and CD34(-) erythroid precursors, and increased numbers of CD36(-/lo) erythroid precursors; in addition, the IS was an independent prognostic factor for overall survival.

CONCLUSIONS

Assessment of immunophenotypic abnormalities of maturing/mature BM cells allows an efficient discrimination between MDS and both normal and reactive BM, once the number and degree of severity of the abnormalities detected are simultaneously scored. Interestingly, progressively higher IS were found among patients with MDS with adverse prognostic features and shorter overall survival.

Myelodysplastic syndromes/neoplasms: recent classification system based on World Health Organization Classification of Tumors - International Agency for Research on Cancer for Hematopoietic and Lymphoid Tissues

The myelodysplastic Syndromes (MDS) are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more of the major myeloid cell lines, ineffective hematopoiesis, and increased risk of development of acute myeloid leukemia. The classification and the diagnostic criteria have been redefined by the recent World Health Organization Classification of Tumors – International Agency for Research on Cancer for Hematopoietic and Lymphoid Tissues. The myelodysplastic syndromes are now classified into the following categories – refractory cytopenia with unilineage dysplasia, refractory anemia with ring sideroblasts, refractory cytopenia with multilineage dysplasia, refractory anemia with excess blasts, myelodysplastic syndrome associated with isolated del (5q), myelodysplastic syndrome – unclassifiable, and childhood myelodysplastic syndrome. The clinicopathologic features, morphology, differential diagnosis, immunophenotyping, cytogenetics, prognosis and predictive factors are presented in the light of recent World Health Organization Classification of Tumors – International Agency for Research on Cancer.

Myelodysplastic syndromes classification and risk stratification

Myelodysplastic syndromes (MDS) are spectrum of bone marrow failure disorders that share a common pathologic feature: cytologic dysplasia. The classification of MDS reflects the understanding of the disease. It is hoped that in the future classification and risk stratification will be based on underlying pathobiology of different disease subsets and molecular signatures where the pathologic classification represents their phenotype. This article reviews MDS classification and risk stratification highlighting differences between the various systems.

Diffuse cellular and fibrosing interstitial pneumonitis with desquamative interstitial pneumonitis-like features associated with myeloid neoplasia

Patients with preleukemic myeloid neoplasia can develop nonhematologic disease. Five patients with the myelodysplastic syndrome presented with interstitial lung disease that heralded acute leukemia in 3. Chest radiographs showed diffuse interstitial opacities, and the lung biopsies showed diffuse cellular interstitial and fibrosing pneumonitis with prominent alveolar filling by macrophages. There was no evidence to support a drug-induced or infectious etiology, and all cases lacked an identifiable leukemic infiltration. The inflammatory infiltrates and fibrosis were analyzed morphometrically, and this revealed a trend toward an indirect correlation between both CD68 cells and MPO-positive inflammatory cells and pulmonary fibrosis. We conclude that preleukemic myeloid neoplasia can be associated with an interstitial pneumonitis with histopathologic features that are distinguishable from both leukemic infiltration and "usual" nonspecific interstitial pneumonia.

Erythroid dysplasia, megaloblastic anemia, and impaired lymphopoiesis arising from mitochondrial dysfunction

Recent reports describe hematopoietic abnormalities in mice with targeted instability of the mitochondrial genome. However, these abnormalities have not been fully described. We demonstrate that mutant animals develop an age-dependent, macrocytic anemia with abnormal erythroid maturation and megaloblastic changes, as well as profound defects in lymphopoiesis. Mice die of severe fatal anemia at 15 months of age. Bone-marrow transplantation studies demonstrate that these abnormalities are intrinsic to the hematopoietic compartment and dependent upon the age of donor hematopoietic stem cells. These abnormalities are phenotypically similar to those found in patients with refractory anemia, suggesting that, in some cases, the myelodysplastic syndromes are caused by abnormalities of mitochondrial function.

Standardization of flow cytometry in myelodysplastic syndromes: report from the first European LeukemiaNet working conference on flow cytometry in myelodysplastic syndromes

The myelodysplastic syndromes are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more cell lineages and increased risk of evolution to acute myeloid leukemia (AML). Recent advances in immunophenotyping of hematopoietic progenitor and maturing cells in dysplastic bone marrow point to a useful role for multiparameter flow cytometry (FCM) in the diagnosis and prognostication of myelodysplastic syndromes. In March 2008, representatives from 18 European institutes participated in a European LeukemiaNet (ELN) workshop held in Amsterdam as a first step towards standardization of FCM in myelodysplastic syndromes. Consensus was reached regarding standard methods for cell sampling, handling and processing. The group also defined minimal combinations of antibodies to analyze aberrant immunophenotypes and thus dysplasia. Examples are altered numbers of CD34(+) precursors, aberrant expression of markers on myeloblasts, maturing myeloid cells, monocytes or erythroid precursors and the expression of lineage infidelity markers. When applied in practice, aberrant FCM patterns correlate well with morphology, the subclassification of myelodysplastic syndromes, and prognostic scoring systems. However, the group also concluded that despite strong evidence for an impact of FCM in myelodysplastic syndromes, further (prospective) validation of markers and immunophenotypic patterns are required against control patient groups as well as further standardization in multi-center studies. Standardization of FCM in myelodysplastic syndromes may thus contribute to improved diagnosis and prognostication of myelodysplastic syndromes in the future.

Myelodysplastic syndromes

Session 4 of the 2007 Workshop of the Society for Hematopathology/European Association for Haematopathology was devoted to myelodysplastic syndromes (MDSs). Submitted cases highlighted important issues and difficulties in relation to the diagnosis and classification of MDS. Much of the discussion focused on the correlation, or lack of it, between morphologic examination and other diagnostic techniques, cytogenetics in particular. The cases included examples of isolated del(5q) chromosomal abnormality, including the "classical" 5q- syndrome and other myeloid neoplasms. Other cytogenetic abnormalities in MDSs and the role of cytogenetics in diagnosing MDSs were addressed. Particularly challenging is the correct identification of fibrotic subtypes of MDSs and their separation from subsets of acute myeloid leukemia with myelofibrosis such as acute panmyelosis with myelofibrosis. The association and eventual relation of MDSs (hypoplastic in particular) with aplastic anemia, paroxysmal nocturnal hemoglobinuria, and other nonneoplastic disorders were illustrated. Novel cytogenetic and molecular genetic approaches are likely to revolutionize the classification of MDSs. However, it is unlikely that these new techniques will be capable, on their own, of adequately stratifying patients for treatment purposes. At least for the foreseeable future, the diagnosis of MDS requires integration of morphologic, immunophenotypic, and genetic features in the light of patient history and clinical manifestations.