Distinguishing myelodysplastic syndromes (MDS) from idiopathic cytopenia of undetermined significance (ICUS): HUMARA unravels clonality in a subgroup of patients

MDS patient registries - achievements and challenges

Since the late 1980s, patient registries have played a pivotal role in the elucidation of rare diseases. For myelodysplastic syndromes (MDS), they revealed the disease actually to be diverse rather than rare. Registry data enabled the definition of various MDS subtypes and prognostic scores tailoring therapy. These classifications have been revised and refined several times, and the differential diagnosis of MDS has become increasingly complex. At the same time, the diagnosis has been made more commonly and no longer by specialized centers of expertise only. Consequently, several registries have collected data with different focuses and from different patient subpopulations. The current review presents three MDS registries and their rationale, scope, design, and achievements. All three complement each other and will remain a mainstay to advance the knowledge on MDS as well as to validate the outcomes of clinical trials. However, delineation of subtypes after the most recent WHO and IPC revisions, as well as the determination of the newest risk score M of the International Prognostic Scoring System (IPSS-M), no longer just shift cut-offs but are based on multivariate compilations of highly specific genetic information. This paradigm shift involves challenging registries with respect to the assignment of all patients for whom this information has not yet been available.

Molecular and clinical aspects relevant for counseling individuals with clonal hematopoiesis of indeterminate potential

Clonal hematopoiesis of indeterminate potential (CHIP) has fascinated the medical community for some time. Discovered about a decade ago, this phenomenon links age-related alterations in hematopoiesis not only to the later development of hematological malignancies but also to an increased risk of early-onset cardiovascular disease and some other disorders. CHIP is detected in the blood and is characterized by clonally expanded somatic mutations in cancer-associated genes, predisposing to the development of hematologic neoplasms such as MDS and AML. CHIP-associated mutations often involve DNA damage repair genes and are frequently observed following prior cytotoxic cancer therapy. Genetic predisposition seems to be a contributing factor. It came as a surprise that CHIP significantly elevates the risk of myocardial infarction and stroke, and also contributes to heart failure and pulmonary hypertension. Meanwhile, evidence of mutant clonal macrophages in vessel walls and organ parenchyma helps to explain the pathophysiology. Besides aging, there are some risk factors promoting the appearance of CHIP, such as smoking, chronic inflammation, chronic sleep deprivation, and high birth weight. This article describes fundamental aspects of CHIP and explains its association with hematologic malignancies, cardiovascular disorders, and other medical conditions, while also exploring potential progress in the clinical management of affected individuals. While it is important to diagnose conditions that can lead to adverse, but potentially preventable, effects, it is equally important not to stress patients by confronting them with disconcerting findings that cannot be remedied. Individuals with diagnosed or suspected CHIP should receive counseling in a specialized outpatient clinic, where professionals from relevant medical specialties may help them to avoid the development of CHIP-related health problems. Unfortunately, useful treatments and clinical guidelines for managing CHIP are still largely lacking. However, there are some promising approaches regarding the management of cardiovascular disease risk. In the future, strategies aimed at restoration of gene function or inhibition of inflammatory mediators may become an option.

The National MDS Natural History Study: design of an integrated data and sample biorepository to promote research studies in myelodysplastic syndromes

Myelodysplastic syndromes (MDS), a spectrum of heterogeneous hematopoietic stem cell diseases, vary in clinical severity, response to therapy, and propensity toward progression to acute myeloid leukemia. These are acquired clonal disorders resulting from somatic mutations within the hematopoietic stem or progenitor cell population. Understanding the natural history and the risk of developing leukemia and other adverse outcomes is dependent on access to well-annotated biospecimens linked to robust clinical and molecular data. To facilitate the acquisition and distribution of MDS biospecimens to the wider scientific community and support scientific discovery in this disease, the National MDS Natural History study was initiated by the National Heart, Lung, and Blood Institute (NHLBI) and is being conducted in collaboration with community hospitals and academic medical centers supported by the National Cancer Institute (NCI). The study will recruit up to 2000 MDS patients or overlapping myeloproliferative neoplasms (MDS/MPN) and up to 500 cases of idiopathic cytopenia of undetermined significance (ICUS). The National MDS Natural History Study (NCT02775383) will offer the world's largest disease-focused tissue biobank linked to longitudinal clinical and molecular data in MDS. Here, we report on the study design features and describe the vanguard phase of 200 cases. The study assembles a comprehensive clinical database, quality of life results, laboratory data, histopathology slides and images, genetic information, hematopoietic and germline tissues representing high-quality biospecimens and data from diverse centers across the United States. These resources will be available to the scientific community for investigator-initiated research.

ICUS, IDUS, CHIP and CCUS: Diagnostic Criteria, Separation from MDS and Clinical Implications

Various myeloid neoplasms, including the myelodysplastic syndromes (MDS), bear a certain risk of progression to secondary acute myeloid leukemia (sAML). The evolution from low-risk to high-risk MDS and finally to sAML suggests that leukemogenesis is a multistep process. However, even before an overt neoplasm, such as an MDS, develops, "prediagnostic" clonal conditions may be identified. With the advent of large-scale genomic screens, such conditions may be detected quite frequently and early in apparently healthy individuals. Recent data suggest that these conditions increase with age and are indeed associated with an increased risk of the occurrence of MDS or another myeloid neoplasm. In other patients, unexplained cytopenia may be detected and may precede MDS. More recently, diagnostic criteria for potential pre-MDS conditions, including idiopathic cytopenia of uncertain significance and clonal hematopoiesis with indeterminate potential, have been proposed. The current article provides an overview of pre-MDS states and related criteria through which these conditions can be discriminated from each other and from MDS. In addition, the clinical implications and management of pre-MDS states are discussed.

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.

ICUS/CCUS/CHIP: basics & beyond

INTRODUCTION

Patients presenting with idiopathic cytopenia with non-diagnostic marrow morphology and a normal karyotype pose a diagnostic and therapeutic challenge. Additional diagnostic information from mutation analysis could provide important clinical insights. However, one has to be cautious during such diagnostic interpretations in view of the recent documentation of clonal somatic mutations in healthy elder individuals. Whether to regard clonality synonymous with malignant proliferation or a manifestation of ageing process is to be judged carefully. Areas covered: The review covers defining criteria and diagnostic work up for Idiopathic cytopenia of undetermined significance (ICUS), Clonal cytopenia of undetermined significance (CCUS), Clonal hematopoiesis of indeterminate potential (CHIP). It also presents the results from previous reports on this subject. In addition the evolution and potential impact of these entities is discussed. Expert commentary: Current evidence does not support the use of somatic mutations as presumptive evidence of myelodysplastic syndrome (MDS). Including CCUS under the category of MDS requires further insight on natural disease course. Longitudinal follow up study on ICUS, CCUS, CHIP may eventually identify the pathological significance of the clonal mutations. An absence of mutation however may still be useful as good predictor of not having MDS.

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.

The relationship between idiopathic cytopenias/dysplasias of uncertain significance (ICUS/IDUS) and autoimmunity

INTRODUCTION

This review examines the several lines of evidence that support the relationship between myelodysplasia and autoimmunity, i.e. their epidemiologic association, the existence of common immune-mediated physiopathologic mechanisms, and the response to similar immunosuppressive therapies. The same relationship is reviewed here considering idiopathic cytopenia of uncertain significance (ICUS) and idiopathic dysplasia of uncertain significance (IDUS), two recently recognized provisional conditions characterized by isolated/unexplained cytopenia and/or dysplasia in <10% bone marrow cells. Areas covered: The review focuses on alterations of cytokine profiles, telomere/telomerase and toll-like receptors, and on increased myelosuppressive mediators and apoptotic markers in both myelodysplasia and autoimmunity. In addition, the presence of an autoimmune reaction directed against marrow precursors is described in refractory/relapsing autoimmune cytopenias (autoimmune hemolytic anemia, immune thrombocytopenia, chronic idiopathic neutropenia), possibly contributing to their evolution to ICUS/IDUS/bone marrow failure syndromes. Expert commentary: The increasing availability of omics methods has fuelled the discussion on the role of somatic mutations in the pathogenesis of IDUS/ICUS, clonal hematopoiesis of indeterminate potential, and clonal cytopenias of undetermined significance, and in their possible evolution. Even more attracting is the involvement of the genetic background/accumulating somatic mutations in cytopenias with autoimmune alterations.

New proposals of the WHO working group (2016) for the diagnosis of myelodysplastic syndromes (MDS): Characteristics of refined MDS types

Based on centrally diagnosed 3528 patients in the Düsseldorf registry, we validated the new proposals for the classification of the MDS by the WHO working group: 256 patients were diagnosed as MDSSLD (7,3%), 978 MDSMLD (27,7%), 227 MDS RS SLD (6,4%); 321 MDS RS MLD (9,1%), 159 MDS del(5q) (4,5%), 481 MDSEB 1 (13,6%), 620 MDSEB 2 (17,6%), and 148 MDS-U (4,2%). 352 patients (16,9% of the non blastic types) changed the category, mainly moving from RCMD to MDS RS MLD, RCUD and RCMD to MDS del(5q). Median survival times of the refined groups differed from more than 60 months in the MDSSLD (RS) groups, 37 months in the MDSMLD (RS) groups, 79 months of the MDS del(5q) group and 21 and 11 months in the MDSEB 1 and 2 groups, respectively. The difference between the groups with regard to the risk of AML evolution was also impressing. No major changes were made with regard to the MDS-U categories. In summary, the proposals of the WHO group for the classification of MDS are thoughtful, taking into account biologic parameters of the diseases, a more precise wording, to some extend pragmatic and feasible.

Idiopathic Fatal Pancytopenia: A Case Report

Pancytopenia is defined as decrease in red blood cells, white blood cells and platelets. Many disease processes involve the bone marrow primarily or secondarily resulting in pancytopenia. A 55-year-old male presented with generalized body weakness and few episodes of malena for last one year. Physical and systemic examination was unremarkable. CBC report revealed pancytopenia. Other haematological parameters were within normal limit. Stool for occult blood was positive. USG and CECT abdomen showed no abnormality. The patient was evaluated for any evidence of malignancy but no clue was found. Bone marrow examination was done as patient was having pancytopenia. Bone marrow smears, clot sections and bone marrow biopsy was normal. Immunohistochemistry and cytogenetics study was unremarkable. Patient was admitted in hospital for 1 month and his condition rapidly deteriorated. The cause of pancytopenia remained unexplained and therefore it was named as Idiopathic fatal pancytopenia. "Idiopathic Fatal Pancytopenia (IFP)" is an emerging new entity with a grave prognosis. We wish to sensitize the medical community and the scientists to this rapidly fatal condition.

The shadowlands of MDS: idiopathic cytopenias of undetermined significance (ICUS) and clonal hematopoiesis of indeterminate potential (CHIP)

The WHO classification provides the best diagnostic approach to myelodysplastic syndromes (MDS). However, biologic and analytic limitations have emerged in the criteria currently adopted to establish the diagnosis and to classify MDS. The provisional category of idiopathic cytopenia of undetermined significance (ICUS) has been proposed to describe patients in whom MDS is possible but not proven. To formulate a diagnosis of ICUS, a thorough diagnostic work-up is required and repeated tests should be performed to reach a conclusive diagnosis. Recent studies provided consistent evidence of age-related hematopoietic clones (clonal hematopoiesis of indeterminate potential; CHIP), driven by mutations of genes that are recurrently mutated in myeloid neoplasms and associated with increase in the risk of hematologic cancer. A subset of mutated genes, mainly involved in epigenetic regulation, are likely initiating lesions driving the expansion of a premalignant clone. However, in a fraction of subjects the detected clone may be a small malignant clone expanding under the drive of the detected and additional undetected mutations. In addition, several experimental evidences suggest the potential relevance of an abnormal bone marrow environment in the selection and evolution of hematopoietic clones in MDS. The spreading of massively parallel sequencing techniques is offering translational opportunities in the clinical approach to myeloid neoplasms. Although several issues remain to be clarified, targeted gene sequencing may be of potential value in the dissection between clonal myelodysplasia, nonclonal cytopenia, and clonal hematopoiesis arising upon aging or in the context of acquired marrow failure.

MDS-associated somatic mutations and clonal hematopoiesis are common in idiopathic cytopenias of undetermined significance

Establishing a diagnosis in patients suspected of having a myelodysplastic syndrome (MDS) can be challenging and could be informed by the identification of somatic mutations. We performed a prospective study to examine the frequency and types of mutations encountered in 144 patients with unexplained cytopenias. Based on bone marrow findings, 17% were diagnosed with MDS, 15% with idiopathic cytopenias of undetermined significance (ICUS) and some evidence of dysplasia, and 69% with ICUS and no dysplasia. Bone marrow DNA was sequenced for mutations in 22 frequently mutated myeloid malignancy genes. Somatic mutations were identified in 71% of MDS patients, 62% of patients with ICUS and some dysplasia, and 20% of ICUS patients and no dysplasia. In total, 35% of ICUS patients carried a somatic mutation or chromosomal abnormality indicative of clonal hematopoiesis. We validated these results in a cohort of 91 lower-risk MDS and 249 ICUS cases identified over a 6-month interval. Mutations were found in 79% of those with MDS, in 45% of those with ICUS with dysplasia, and in 17% of those with ICUS without dysplasia. The spectrum of mutated genes was similar with the exception of SF3B1 which was rarely mutated in patients without dysplasia. Variant allele fractions were comparable between clonal ICUS (CCUS) and MDS as were mean age and blood counts. We demonstrate that CCUS is a more frequent diagnosis than MDS in cytopenic patients. Clinical and mutational features are similar in these groups and may have diagnostic utility once outcomes in CCUS patients are better understood.

Myelodysplastic Syndromes Diagnosis: What Is the Role of Molecular Testing?

Diagnosing a myelodysplastic syndrome (MDS) can be challenging. Somatic mutations are common in MDS and might have diagnostic utility in patients with idiopathic cytopenias of undetermined significance (ICUS). However, using mutations to diagnose MDS is complicated by several issues: (1) no gene is mutated in most cases, (2) no mutated gene is highly specific for MDS, (3) clonal hematopoiesis is common in older individuals without disease, and (4) we lack outcome data for ICUS patients with clonal cytopenias of undetermined significance (CCUS). Despite these caveats, genetic sequencing can inform the diagnosis of MDS. CCUS patients more closely resemble patients with MDS than age matched controls with somatic mutations. Genetic testing can identify alternative diagnoses in cytopenic patients and help risk stratify those with proven MDS. While we cannot include somatic mutations in the diagnostic definition of MDS now, testing to recognize CCUS will help characterize outcomes in these diagnostically challenging patients.

High frequency of autonomous T-cell proliferation compatible with T-cell large granular lymphocytic leukemia in patients with cytopenia of unknown etiology

Large granular lymphocytic leukemia/lymphoproliferative disorder (LGL-L/LPD) is a heterogeneous neoplastic disease of large granular lymphocytes and is a well-known cause of cytopenias. We aimed to reveal the incidence of LGL-L/LPD in patients with cytopenia(s) of unknown etiology (CUE). Twenty-eight patients with CUE were investigated for LGL-L/LPD. T-cell LGL leukemia (LGL-L) was diagnosed in 12 (42.9 %) patients. The frequencies of LGL-L in patients who had anemia, neutropenia, and thrombocytopenia were 9/14 (64.2 %), 11/23 (47.8 %), and 3/10 (30 %), respectively. Seventeen of the 28 patients met the criteria of idiopathic cytopenia of undetermined significance (ICUS), and LGL-L was found in six (35.3 %) of them. We conclude that LGL-L is a rather common disease in patients with CUE and ICUS. It should be considered in this patient group and investigated thoroughly.

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.

Dysplasia has A differential diagnosis: distinguishing genuine myelodysplastic syndromes (MDS) from mimics, imitators, copycats and impostors

Just as a pawnshop owner who is unable to distinguish a genuine Rolex™ watch from a cheap knockoff courts financial ruin, the physician who fails to discriminate between authentic myelodysplastic syndromes (MDS) and conditions resembling MDS risks misinforming or harming patients. This review summarizes minimal criteria for diagnosing MDS and discusses common diagnostic challenges. MDS needs to be separated from numerous neoplastic and non-clonal hematologic disorders that can mimic MDS, including other myeloid neoplasms, nutritional deficiencies, toxin exposures, aplastic anemia, and inherited disorders (e.g., congenital sideroblastic anemia). Some distinctions are more critical therapeutically than others; e.g., recognizing B12 deficiency is more important than parsing high-risk MDS from erythroleukemia. Diagnostically ambiguous cases may be assigned holding-pattern terms, "idiopathic cytopenia(s) of undetermined significance" (ICUS) or "idiopathic dysplasia of undetermined significance" (IDUS), while awaiting clarifying information or further clinical developments. In the future, advances in molecular pathology will improve diagnostic accuracy, especially in morphologically non-descript cases.

Low blood counts: immune mediated, idiopathic, or myelodysplasia

Traditionally, cytopenias are classified as deficiency mediated, immune mediated, BM failure induced, renal, or idiopathic, with the latter including the so-called idiopathic cytopenias of undetermined significance (ICUS). Clinical findings, symptoms, blood counts, BM findings, and other laboratory parameters are usually sufficient to reveal the type and cause of a marked cytopenia. However, in patients with chronic mild cytopenia, it may be a challenge for the physician to establish a correct diagnosis. In such patients, laboratory features and findings often reflect a diagnostic interface, so that criteria that are otherwise robust may hardly be applicable or are not helpful. Even if the BM is examined, the diagnosis often remains uncertain in these patients. In addition, more than one potential cause of cytopenia may be present, especially in the elderly. A myelodysplastic syndrome (MDS) or another BM disorder, but also an overt autoimmune or other inflammatory disease, may develop during follow-up in these patients. A key problem is that in an early phase of MDS, most laboratory and clinical signs are “nonspecific.” One of the very few reliable peripheral blood parameters distinguishing between an early or “pre-phase” of MDS and most other causes of a mild cytopenia are the numbers of circulating colony-forming progenitor cells. In addition, flow cytometric and molecular investigations may sometimes assist in the delineation between clonal and reactive conditions underlying mild cytopenias. This review provides an overview of diagnostic approaches and algorithms for patients with mild unexplained cytopenia(s).

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.

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.

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.