Pathology of the myeloproliferative diseases

The classification of myeloid neoplasms now includes CMPD, mixed CMPD/ MDS, MDS, and acute myeloid leukemias. CMPD and CMPD/MDS, both clonal stem cell diseases, share myeloproliferative features, including typical hypercellular marrows, organomegaly, and cell lineage maturation. The CMPD generally differ by which myeloid cell lineage dominates hematopoiesis, and the main diseases include CML, PV, ET, and CIM. The mixed CMPD/MDS disorders also show dysplastic features and variable amounts of effective hematopoiesis; these disorders include CMML, JMML, and atypical CML. Given the overlap in morphology among these diseases, correlation with clinical, hematologic, and cytogenetic/molecular genetic findings is imperative for precise classification.     

Molecular Testing in Patients with Suspected Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal hematologic malignancies characterized by a hypercellular bone marrow and morphologic dysplasia in one or more lineage (i.e., myeloid, erythroid, or megakaryocytic), presenting clinically with leukopenia, anemia, and/or thrombocytopenia and with a propensity to transform to acute myelogenous leukemia. Newer technologies such as next-generation sequencing have allowed better understanding of the genetic landscape in MDS. Nearly 80 % of MDS patients have at least one mutation, and approximately 40 recurrent somatic mutations have been identified to occur in >1 % of cases. Many of these mutations are relevant for prognosis, help with selection of therapy, and/or have specific targeted treatment options. In this article, we will explore the impact of molecular testing on diagnosis, prognosis, and treatment decisions in patients with suspected MDS.     

Updates in Cytogenetics and Molecular Markers in MDS

Myelodysplastic syndromes (MDS) are clonal hematologic neoplasms that can result in cytopenias and increase the risk of leukemic transformation. The disease is characterized by several recurrent cytogenetic defects, which can affect diagnosis, prognosis, and treatment. Metaphase cytogenetics (MC) is the gold standard in karyotypic analysis in hematology. Progress in molecular analysis, including additional karyotypic tools exemplified by fluorescence in situ hybridization, comparative genomic hybridization, and more importantly, single nucleotide polymorphism array (SNP-A) analysis, has led to increased detection of chromosomal abnormalities in myeloid malignancies and improved prognostic risk stratification. SNP-A, together with MC, has also been instrumental in the discovery of genes that have improved our understanding of the biology of MDS. Newly elucidated molecular abnormalities in MDS include mutations in CBL, TET2, ASXL1, IDH1/IDH2, EZH2, DNMT3A, and UTX. This review provides an update on the changing landscape of molecular and cytogenetic characterization in MDS and its significance in disease biology and clinical practice.     

SOHO State of the Art Update and Next Questions: Biology and Treatment of Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid neoplasms characterized by clonal hematopoiesis leading to bone marrow dysplasia and cytopenias. Recently, significant advancements have been made in understanding the pathogenic mechanisms of this disease. In particular, how a wide array of somatic mutations can induce a common clinical phenotype has been investigated. Specifically, activation of innate immune signaling (i.e. myeloid derived suppressor cells) and the NLRP3 inflammasome in hematopoietic stem/progenitor cells play a central role in the biology of MDS, leading to pyroptotic cell death and clonal expansion. Additionally, deciphering the molecular drivers of MDS using next-generation sequencing has rapidly expanded our understanding of MDS with profound implications for prognosis, treatment decisions, and future clinical investigations. Together, unraveling of the role of innate immunity/pyroptosis in the clinical phenotype of MDS patients and comprehensive molecular characterization has identified novel therapeutic strategies that offer significant promise.     

Idiopathic cytopenia of undetermined significance (ICUS) and idiopathic dysplasia of uncertain significance (IDUS), and their distinction from low risk MDS

It is now generally appreciated that hematologic neoplasms can develop over many years if not decades, often being initially occult or showing minimal (subdiagnostic) abnormalities. However, whereas such early neoplastic conditions have been defined in some detail in lymphoproliferative neoplasms, little is known about minimal lesions preceding the manifestation of an overt myeloid neoplasm, about underlying mechanisms, the clinical course and outcome, and the prognostic significance of such conditions. Members of several groups have recently described two ‘premalignant’ myeloid conditions, namely idiopathic cytopenia of undetermined significance (ICUS) and idiopathic bone marrow dysplasia of uncertain significance (IDUS). At least in some patients these are neoplastic conditions. Both conditions may progress to an overt myelodysplastic syndrome (MDS), but may also progress to another myeloid neoplasm such as acute myeloid leukemia, a myeloproliferative neoplasm (MPN), or a mast cell disorder (mastocytosis). In ICUS the dysplasia is mild and does not fulfill the WHO criteria for MDS but cytopenias can be severe. In IDUS the dysplasia is prominent but cytopenias, if detectable, are mild. In both conditions it is possible that a neoplastic clone has already replaced most or all of normal bone marrow cells when ICUS or IDUS is detected, but evidence to support this possibility is not necessarily available. For both groups of patients we recommend a thorough hematologic follow up because of the potential of disease-manifestation and the unpredictable form and time of progression. In the present review, we discuss current concepts relating to ICUS and IDUS as well as diagnostic approaches and available criteria.     

Cytogenetic aspects of adult primary myelodysplastic syndromes: clinical implications

Myelodysplastic syndrome (MDS) is a heterogeneous disease from the clinical, biological and morphological point of view. The pathogenesis of MDS is not well established and it appears to occur complex changes in the stem cell biology. Clonal chromosomal aberrations are found in 30-50% of primary MDS and no specific cytogenetic abnormality has as yet been defined. The chromosomal abnormalities are predominantly characterized by partial/total chromosomal losses or chromosomal gains. These chromosomal abnormalities include mainly -5/del(5q), -7/del(7q), del(11q), del(12p), del(20q), -Y, and +8. The role of cytogenetic analysis in the diagnosis, prognosis, taking treatment decisions and follow up of patients with MDS has been clearly defined. Despite its difficulties in obtaining for analysis high quality metaphases conventional cytogenetics continues to be the basic technique for cytogenetic evaluation of a MDS patient. Other molecular cytogenetic methods have been shown to be complementary, without replacing the information obtained with this technique. Further investigations with both conventional and molecular cytogenetics in relation to clinical features as well as other molecular methods will undoubtedly contribute to improve understanding of the underlying genetic events responsible for the development and evolution of MDS leading to more accurate classification and management of MDS patients.     

Revisiting use of growth factors in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal hematologic neoplasms characterized by morphologic dysplasia, aberrant hematopoiesis and peripheral blood refractory cytopenias. MDS is recognized to be associated with an increased risk of symptomatic anemia, infectious complications and bleeding diathesis, as well as a risk of progression to acute myeloid leukemia, particularly in patients with a high IPSS score. The advent of use of hematopoietic growth factors such as granulocyte colony-stimulating factor (G-CSF) and recombinant erythropoietin (EPO) has improved symptoms in MDS patients in addition to some data that suggest there might be an improvement in survival. G-CSF is an effective therapeutic option in MDS patients, and it should be considered for the management of refractory symptomatic cytopenias. G-CSF and EPO in combination can improve outcomes in appropriate MDS patients such as those with lower-risk MDS and refractory anemia with ring sideroblasts (RARS) . This article reviews use of growth factors for lower-risk MDS patients, and examines the data for G-CSF, EPO and thrombopietic growth factors (TPO) that are available or being developed as therapeutic modalities for this challenging disease.     

Standards and impact of hematopathology in myelodysplastic syndromes (MDS)

The diagnosis, classification, and prognostication of patients with myelodysplastic syndromes (MDS) are usually based on clinical parameters, analysis of peripheral blood and bone marrow smears, and cytogenetic determinants. However, a thorough histologic and immunohistochemical examination of the bone marrow is often required for a final diagnosis and exact classification in these patients. Notably, histology and immunohistology may reveal dysplasia in megakaryocytes or other bone marrow lineages and/or the presence of clusters of CD34-positive precursor cells. In other cases, histology may reveal an unrelated or co-existing hematopoietic neoplasm, or may support the conclusion the patient is suffering from acute myeloid leukemia rather than MDS. Moreover, histologic investigations and immunohistology may reveal an increase in tryptase-positive cells, a coexisting systemic mastocytosis, or bone marrow fibrosis, which is of prognostic significance. To discuss diagnostic algorithms, terminologies, parameters, and specific issues in the hematopathologic evaluation of MDS, a Working Conference involving a consortium of US and EU experts, was organized in June 2010. The outcomes of the conference and resulting recommendations provided by the faculty, are reported in this article. These guidelines should assist in the diagnosis, classification, and prognostication in MDS in daily practice as well as in clinical trials.     

Flow cytometry evaluation of erythroid and myeloid dysplasia in patients with myelodysplastic syndrome.

The purpose of this study was to develop a flow cytometric approach to the evaluation of marrow dysplasia in myelodysplastic syndromes (MDS). We first studied a cohort of 103 MDS patients as well as 46 pathological and healthy controls. Flow cytometry data were expressed as percentage of positive cells. Analysis of erythroid cells showed higher proportions of immature cells (P < 0.001) and decreased levels of CD71 expression on nucleated red cells (P = 0.02) in MDS. Analysis of myeloid cells showed lower proportions of CD10+ and higher proportions of CD56+ granulocytes (P < 0.001), and increased ratios of immature to mature cells (P = 0.007). Since no single immunophenotype could accurately differentiate MDS from other conditions, we used discriminant analysis for generating erythroid and myeloid classification functions using combinations of immunophenotypic parameters. These functions were prospectively validated in a testing cohort of 69 MDS patients and 46 pathological controls. A diagnosis of MDS was obtained in 60/69 cases (87%). No false-positive results were noticed among controls. Significant correlations between values of these functions and both degree of morphological dysplasia and the International Prognostic Scoring System were found. These findings indicate that flow cytometry evaluation of marrow dysplasia is feasible and may be useful in the work-up of individual MDS patients.     

Molecular Testing in Myelodysplastic Syndromes for the Practicing Oncologist: Will the Progress Fulfill the Promise?

Myelodysplastic syndromes (MDS) are heterogeneous hematopoietic neoplasms that are driven by somatically acquired genetic mutations and epigenetic alterations. Accurate risk stratification is essential for delivery of risk-adaptive therapeutic interventions. The current prognostic tools sum the impact of clinical, pathologic, and laboratory parameters. Newer technologies with next-generation targeted deep sequencing and whole-genome and -exome sequencing have identified several recurrent mutations that play a vital role in the pathophysiology of MDS and the impact of these genetic changes on disease phenotype. Equally important, well-annotated databases of MDS patients with paired clinicopathologic and genetic data have enabled better understanding of the independent prognostic impact of several molecular mutations on important clinical endpoints such as overall survival and probability of leukemic progression. Cumulative evidence suggests that genomic data can also be used clinically to aid with the diagnosis, prognosis, prediction of response to specific therapies, and the development of novel and rationally targeted therapies. However, the optimal use of this mutational profiling remains a work in progress and currently there is no standard set of genes or techniques that are recommended for routine use in the clinic. In this review, we discuss the genomic revolution and its impact on our understanding of MDS biology and risk stratification. We also discuss the current role and the challenges of the application of genetic mutational data into daily clinical practice and how future research could help improve the prognostication precision and specific therapy selection for patients with MDS.

Implications for Practice:

Heterogeneity in clinical outcomes of MDS is partly related to interpatient variability of recurrent somatic mutations that drive disease phenotype and progression. Although clinical risk stratification tools have functioned well in prognostication for patients with MDS, their ability to predict clinical benefits of specific MDS therapies is limited. Molecular testing shows promise in aiding diagnosis, risk stratification, and therapy-specific benefit prediction for MDS patients. Nonetheless, logistical issues related to assay performance standardization, validation, interpretation, and development of guidelines for how to use the results to inform clinical decisions are yet to be resolved.     

Myelodysplastic syndromes, aging, and age: correlations, common mechanisms, and clinical implications

Myelodysplastic syndromes (MDS) are a heterogenous group of myeloid neoplasms that develop primarily in elderly patients. Although a specific molecular basis for the predominant incidence of MDS in higher age groups remains unknown, several lines of evidence suggest that the biology of aging and the pathogenesis of MDS share several genetic, epigenetic, and molecular features. The current review attempts to delineate these common aspects as well as additional discriminative features that are specific for MDS and thus help explaining disease-evolution and progression. In addition, the present review discusses age as an important prognostic factor and co-variable to be considered in treatment algorithms in MDS.     

The role of mutations in epigenetic regulators in myeloid malignancies

Recent genomic studies have identified novel recurrent somatic mutations in patients with myeloid malignancies, including myeloproliferative neoplasms (MPNs), myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). In some cases these mutations occur in genes with known roles in regulating chromatin and/or methylation states in haematopoietic progenitors, and in other cases genetic and functional studies have elucidated a role for specific mutations in altering epigenetic patterning in myeloid malignancies. In this Review we discuss recent genetic and functional data implicating mutations in epigenetic modifiers, including tet methylcytosine dioxygenase 2 (TET2), isocitrate dehydrogenase 1 (IDH1), IDH2, additional sex combs-like 1 (ASXL1), enhancer of zeste homologue 2 (EZH2) and DNA methyltransferase 3A (DNMT3A), in the pathogenesis of MPN, MDS and AML, and discuss how this knowledge is leading to novel clinical, biological and therapeutic insights.     

Usefulness of cytogenetics in leukemias

Present study consists of cytogenetic evaluation in 141 cases referred to our centre for various leukemias. This includes 110 cases of CML, 10 of ALL, 16 of AML (M3), 2 of AML(M2), 2 of MDS and 1 of CMML. The conventional cytogenetic study was carried out in all the cases using G Banding technique. Of the 141 patients studied, 17 patients showed secondary chromosomal alterations along with primary chromosomal alterations. In two patients of CML with secondary chromosomal alteration t(4:9:22), molecular cytogenetic technique (FISH) has been carried out which has confirmed the primary observations revealed by the conventional cytogenetic technique. Other secondary alterations were numerous and would have been missed if only FISH or PCR technique would have been used for diagnosis. We observed from our study that advanced molecular techniques like FISH and PCR cannot replace the conventional cytogenetic study but are useful as supportive and confirmative diagnostic tools.     

Malignant hematopoietic cell lines: in vitro models for the study of myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are clonal myeloid disorders characterized by bone marrow cell dysplasia and ineffective hematopoiesis leading to peripheral refractory cytopenias. The course of the disease ranges from a chronic status with progressively impaired hematopoiesis to rapid evolution to acute myeloid leukemia (AML). A panel of continuous malignant hematopoietic cell lines has been established from the whole spectrum of MDS variants and also from the different stages of the diseases, namely from the MDS phase or the overt leukemia post-MDS phase. Ten cell lines were derived from the various MDS subtypes; 17 cell lines were established from patients with leukemia (mainly AML) post-MDS. While most cell lines display myelocytic, monocytic or erythroid features, some cell lines carry lymphoid characteristics (precursor B-cell, B-cell, or T-cell), With regard to these lymphoid MDS-derived cell lines, more detailed authentication (prove of derivation from the assumed patient) and verification (prove of the malignant nature of the cell line and derivation from the assumed neoplastic cells) are required to validate the cell lines as true in vitro representatives of MDS and to exclude any cross-contamination with other cells or immortalization of normal bystander cells. On the other hand, lymphoid MDS-derived cell lines may attest to the clonal nature of MDS which may afflict progenitor cells giving rise to lymphoid or myelomonocytoid cells. Many of the MDS-derived cell lines carry cytogenetic and molecular genetic abnormalities typically associated with MDS: gain or loss of all or parts of chromosomes 5, 7, 8 and 20 (-5/5q-, -7/7q-, + 8, 20q-); alterations of oncogenes and tumor suppressor genes (IRF-1, p15, p16, p53, RAS, RB). In summary, the present panel of cell lines provides continuously growing cells and thus unlimited cell material for use as in vitro paradigms covering the whole spectrum of MDS-related hematopoetic malignancies. Properly authenticated and verified MDS-derived cell lines which should be made freely available will represent important research tools for the study of MDS biology.     

原因不明的特发性血细胞减少和方向不明的克隆造血

介绍世界卫生组织（WHO）对骨髓增生异常综合征（MDS）中原因不明的特发性血细胞减少（ICUS）和方向不明的克隆造血（CHIP）的解读。MDS的诊断基于2个特征，即病态造血的证据和克隆造血的证据。病态造血用于描述伴1系或以上血细胞系列形态学异常。MDS中检测到的绝大多数染色体异常或基因损伤不是特异性的，而在缺少形态学或无细胞遗传学异常的情况下，排除或明确MDS的诊断则极具挑战性。为了描述可疑但未确诊的MDS，引入了意义不明的ICUS的概念。 CHIP目前定义那种未明确诊断为肿瘤，但是携带与血液系统肿瘤相关体细胞突变基因的状态。大规模平行测序技术的推广，为髓系肿瘤临床治疗提供了良机。尽管关于克隆造血的肿瘤潜能和其意义的问题仍有待于说明，但是基因测序在鉴别克隆性病态造血、非克隆性血细胞减少、由于衰老或其他原因导致的获得性骨髓衰竭相关的克隆造血等方面是非常有价值的。     

Clinical Aspects, Cytogenetics and Disease Evolution in Myelodysplastic Syndromes

Myelodysplastic syndrome (MDS) is a morphologically characterized hematologic entity that is one of the clonal myeloproliferative disorders. Approximately 50 ∼ 70% of MDS patients have cytogenetic abnormalities; these are usually chromosomal deletions, but some involve translocations such as t(1;7)(q10;p10). Translocations involving chromosomal regions 3q26 or 22q11 are often therapy-related. Recent studies have demonstrated that cytogenetic changes in MDS patients have clinical relevance. Accordingly, there are now scoring systems for predicting the prognoses of MDS patients. In this review, we describe the clinical significance of cytogenetic changes in MDS. We include MDS with some atypical forms, such as MDS with hypocellular bone marrow, MDS with minimal dysplasia, and MDS with myelofibrosis.     

Chronic myelomonocytic leukemia and atypical chronic myeloid leukemia: novel pathogenetic lesions

Chronic myelomonocytic leukemia (CMML) and atypical chronic myeloid leukemia (aCML) are distinct, yet related, entities of myelodysplastic/myeloproliferative neoplasms (MDS/MPN) characterized by morphologic dysplasia with accumulation of monocytes or neutrophils, respectively. Our understanding of the molecular pathogenesis of CMML and aCML has advanced, mainly due to the application of novel technologies such as array-based karyotyping and next-generation sequencing. In addition to previously known recurrent aberrations, somatic uniparental disomy affecting chromosomes 3, 4, 7, and 11 frequently occurs in CMML. Novel somatic mutations of genes, including those associated with proliferation signaling (CBL, RAS, RUNX1, JAK2 (V617F)) and with modification of epigenetic status (TET2, ASXL1, UTX, EZH2) have been found. Various combinations of mutations suggest a multistep pathogenesis and may account for clinical heterogeneity. Most recently, several spliceosome-associated-gene mutations were reported and SRSF2 mutations are frequently detected in CMML. The prognostic and diagnostic significance of these molecular lesions, in particular their value as biomarkers of response or resistance to specific therapies, while uncertain now is likely to be clarified as large systematic studies come to completion.     

Array-based cytogenetic approaches in acute myeloid leukemia: clinical impact and biological insights

Conventional cytogenetic studies have shown that the clinical and biological diversity of acute myeloid leukemia (AML) can be attributed, in part, to distinct chromosome aberrations, several of which are now routinely used for diagnosis, risk stratification, and outcome prediction. Although chromosome banding analysis has recently been complemented by the identification of point mutations in a growing number of hematopoiesis-associated genes, current genetic categories do not fully reflect the heterogeneity of AML. To close the gap between standard karyotyping and molecular analyses at the single-base-pair level and gain additional insight into the genetics underlying myeloid leukemogenesis, AML is increasingly being studied using genome-wide, microarray-based cytogenetic methods. These investigations have revealed that AML genomes commonly harbor acquired submicroscopic copy number alterations, even though the prevalence of most of these cryptic lesions appears to be low, as well as regions of uniparental disomy that are often associated with homozygosity of functionally relevant gene mutations. Current efforts are focusing on the application of this expanded knowledge to improve the classification of AML, develop new tools for prognostication and prediction of response to therapy, and accelerate the discovery of genes that are likely to contribute to AML pathogenesis.     

Pathogenetic implications of internuclear bridging in myelodysplastic syndrome. An Eastern Cooperative Oncology Group/Southwest Oncology Group Cooperative Study

Numerous morphologic features have been described in bone marrow and peripheral blood in myelodysplastic syndrome (MDS). We draw attention to a high incidence of a subtle morphologic feature, internuclear bridging (INB), not previously recognized as a morphologic feature in MDS. The occurrence of INB in MDS suggests an underlying abnormality of mitotic division that could explain the impaired production of hematopoietic cells, the addition and deletion cytogenetic changes, and the stepwise disease progression and cytogenetic progression characteristic of MDS. Lack of awareness that INB occurs in MDS may cause confusion of MDS and congenital dyserythropoietic anemia type I, a congenital process also characterized by INB.