Preleukemia. The hematologic syndrome preceding acute leukemia

The trajectory of prognostication and risk stratification for patients with myelodysplastic syndromes

ABSTRACT

Risk stratification and prognostication are crucial for the appropriate management of patients with myelodysplastic syndromes (MDSs) or myelodysplastic neoplasms, for whom the expected survival can vary from a few months to >10 years. For the past 5 decades, patients with MDS have been classified into higher-risk vs lower-risk disease phenotypes using sequentially developed clinical prognostic scoring systems. Factors such as morphologic dysplasia, clinical hematologic parameters, cytogenetics, and, more recently, mutational information have been captured in prognostic scoring systems that refine risk stratification and guide therapeutic management in patients with MDS. This review describes the progressive evolution and improvement of these systems which has led to the current Molecular International Prognostic Scoring System.

Agent Orange and dioxin-induced myeloid leukemia: a weaponized vehicle of leukemogenesis

Agent Orange (AO) was the dominant weaponized herbicide employed by the United States (US) military during the Vietnam war. AO, however, was found to be regularly contaminated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic dioxin known; furthermore, AO was commonly diluted in the field with other aromatic hydrocarbons to assist with delivery mechanisms. Unbeknownst to the US military and the millions exposed, these events have likely contributed to the development of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) that has affected many veterans. Null studies regarding an association between AO exposure and AML/MDS are limited in their methodology and application. The acknowledgement that the known carcinogen TCDD was a contaminant in AO when paired with a strong biological plausibility for its leukemogenicity and an observed increased risk of AML/MDS in TCDD-exposed individuals should suffice to establish causal association and that veterans to whom this might apply should be awarded appropriate indemnity.

A clandestine culprit with critical consequences: Benzene and acute myeloid leukemia

While most clinicians recognize adult therapy-related leukemias following cytotoxic chemotherapy and radiation, environmental regulatory agencies evaluate exposure to "safe levels" of leukemogenic compounds. Benzene represents the most notorious leukemogenic chemical. Used in the production of ubiquitous items such as plastics, lubricants, rubbers, dyes, and pesticides, benzene may be responsible for the higher risk of acute myeloid leukemia (AML) among automobile, janitorial, construction, and agricultural workers. It is possible that ambient benzene may contribute to many cases of "de novo" AML not arising out of germline predispositions. In this appraisal of the available literature, we evaluate and discuss the association between chronic, low-dose and ambient exposure to environmental benzene and the development of adult AML.

Ultrastructural Alterations of Megakaryocytes in Some Hematologic Disorders

Bone marrow and peripheral blood samples of patients affected by hematologic disorders involving the megakaryocytic line were examined at the electron microscope. While in idiopathic thrombocytopenic purpura the megakaryocytes appeared almost normal, in primary thrombocythemia there were various ultrastructural alterations interpreted as a counterpart of ineffective thrombocytopoiesis. In one patient with blastic chronic myeloid leukemia and in another with acute megakaryoblastic leukemia, the electron microscope study was very useful in the identification of immature megakaryocytes. In fact, analysis of various ultrastructural parameters allowed some blast cells to be attributed to the megakaryocytic series. Furthermore, platelet demarcation system abnormalities and alterations of the circulating thrombocytes confirm the hypothesis that there is a block in megakaryocytic maturation.

Preleukemia: one name, many meanings

Definition of preleukemia has evolved. It was first used to describe the myelodysplastic syndrome (MDS) with a propensity to progress to acute myeloid leukemia (AML). Individuals with germline mutations of either RUNX1, CEBPA, or GATA2 can also be called as preleukemic because they have a markedly increased incidence of evolution into AML. Also, alkylating chemotherapy or radiation can cause MDS/preleukemia, which nearly always progress to AML. More recently, investigators noted that AML patients who achieved complete morphological remission after chemotherapy often have clonal hematopoiesis predominantly marked by either DNMT3A, TET2 or IDH1/2 mutations, which were also present at diagnosis of AML. This preleukemic clone represents involvement of an early hematopoietic stem cells, which is resistant to standard therapy. The same clonal hematopoietic mutations have been identified in older ‘normal' individuals who have a modest increased risk of developing frank AML. These individuals have occasionally been said, probably inappropriately, to have a preleukemia clone. Our evolving understanding of the term preleukemia has occurred by advancing technology including studies of X chromosome inactivation, cytogenetics and more recently deep nucleotide sequencing.

Pesticide exposure as a risk factor for myelodysplastic syndromes: a meta-analysis based on 1,942 cases and 5,359 controls

OBJECTIVE

Pesticide exposure has been linked to increased risk of cancer at several sites, but its association with risk of myelodysplastic syndromes (MDS) is still unclear. A meta-analysis of studies published through April, 2014 was performed to investigate the association of pesticide exposure with the risk of MDS.

METHODS

Studies were identified by searching the Web of Science, Cochrane Library and PubMed databases. Summary odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated using random- or fixed-effect models.

RESULTS

This meta-analysis included 11 case-control studies, all of which demonstrated a correlation between pesticide exposure and a statistically significant increased risk of MDS (OR=1.95, 95% CI 1.23-3.09). In subgroup analyses, patients with pesticide exposure had increased risk of developing MDS if they were living in the Europe or Asia and had refractory anemia (RA) or RA with ringed sideroblasts (RARS). Moreover, in the analysis by specific pesticides, increased risk was associated with exposure to insecticides (OR=1.71, 95% CI 1.22-2.40) but not exposure to herbicides or fungicides.

CONCLUSION

This meta-analysis supports the hypothesis that exposure to pesticides increases the risk of developing MDS. Further prospective cohort studies are warranted to verify the association and guide clinical practice in MDS prevention.

Myelodysplastic syndromes in the United States: an update for clinicians

Myelodysplastic syndromes (MDS) are heterogeneous malignant bone marrow disorders diagnosed most often in elderly white persons. MDS have significant clinical consequences, including cytopenias leading to infection, bleeding, and death; and approximately one-third of cases progress to acute myeloid leukemia (AML). Only one potentially curative therapy exists-allogeneic hematopoietic stem cell transplant (HSCT)-but this therapy is not widely used due to associated morbidity and mortality in elderly patients. Recent research suggests MDS occurs more frequently than previously thought and may be responsible for a substantial proportion of unexplained anemias in elderly persons. Incidence of MDS is expected to increase with increases in life expectancy. Therefore, we offer this comprehensive narrative update of MDS to inform the medical community treating the population at risk for MDS, with a focus on MDS epidemiology and clinical management in the United States. This review includes a brief historical background of MDS, provides an overview of the population burden of disease, discusses the molecular pathology of MDS, describes the clinical features and management of MDS, and discusses future directions in MDS research. Our objective is to inform general medicine practitioners and call attention to the need for translational research in MDS.

The epidemiology of myelodysplastic syndromes

The incidence of the myelodysplastic syndromes (MDS) in the United States is reported as 3.4 per 100,000 people, translating to over 10,000 new diagnoses annually. This figure is considered to be an underestimate as our data capture techniques improve, and probably translates to a prevalence of approximately 60,000 people or more living with the disease. Patients are in their seventh or eighth decades at diagnosis, typically present with cytopenias, and have substantive transfusion requirements. The most common risk factors for developing MDS include advanced age, male gender, previous exposure to chemotherapy or radiation therapy, smoking, or, in rare cases, exposure to industrial chemicals.

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.

Secondary hematological changes mimicking the preleukemic syndrome. Report of two cases

Two women with hematological and clinical features typical of the preleukemic syndrome, including low marrow myeloid colony and cluster formation in vitro, showed unexplained spontaneous improvement with normalization of both peripheral blood values and in vitro cloning efficiency after 2-4 years. One patient had and the other developed later an autoimmune disorder. It is therefore suggested that secondary hematopoietic changes might have mimicked the preleukemic syndrome.

Progression of bone marrow abnormalities in malignant hemopoietic dysplasia. Evaluation of cytological changes with serial bone marrow samples

Progression of bone marrow abnormalities in 12 patients with malignant (fatal) hemopoietic dysplasia (HD) was evaluated retrospectively in sequential bone marrow samples, using a simple morphological scoring technique. Special attention was paid to alterations in cytological abnormalities in the myeloid series. Patients who developed acute myeloid leukemia showed increasing scores during the clinical course and a rapid final increase in particularly myeloid nucleolar abnormalities. Patients who did not develop overt myeloid leukemia but died from bleeding and/or infection had low and stable scoring and showed no progression of cytological abnormalities. Repeated evaluation, especially of cytological changes in the bone marrow, and morphological scoring might be useful as predictive tools to estimate the risk of a leukemic transformation in some patients with HD.

Characteristics of US patients with myelodysplastic syndromes: results of six cross-sectional physician surveys

BACKGROUND

Myelodysplastic syndromes (MDS) comprise a group of pathologically and cytogenetically distinct bone marrow disorders. Little is known about the characteristics of MDS patients, including their pathological and prognostic classifications, cytopenias, transfusion and supportive care needs, and treatment regimens. We describe these characteristics in a large group of recently diagnosed and existing (ie, established) MDS patients.

METHODS

We conducted six consecutive cross-sectional surveys among US hematology and medical oncology specialists (identified from an American Medical Association [AMA] database of physicians who administer chemotherapy) between June 2005 and January 2007. A questionnaire collected data on the characteristics and treatment patterns of the 4-10 most recently seen MDS patients for each physician, including demographic data, transfusion needs, treatment approaches, and consideration for clinical trials or bone marrow transplantation.

RESULTS

A panel of 101 physicians who were geographically representative of physicians registered with the AMA characterized 614-827 patients per survey, for a total of 4514 responses. Among recently diagnosed patients, 55% were male (95% confidence interval [CI] = 52% to 59%), the median age at diagnosis was 71 years (range = 65-80 years), and 10% (95% CI = 8% to 12%) had MDS secondary to chemotherapy, radiation therapy, or environmental exposure. The median duration of MDS in established patients ranged from 13 to 16 months over the six surveys. Among recently diagnosed MDS patients, fewer patients with lower-risk disease than with higher-risk disease were dependent on either red blood cell transfusions (22% vs 68%) or platelet transfusions (6% vs 33%). More than 50% of all newly diagnosed and established patients used erythropoiesis-stimulating agents. A small percentage of all patients either had had or were being considered for bone marrow transplantation (recently diagnosed: 4%; established: 4% or less) or were being treated on clinical trials (recently diagnosed: 1%; established: 4% or less).

CONCLUSIONS

MDS patients in the United States have substantial transfusion needs, and use of erythropoiesis-stimulating agents and are seldom considered for bone marrow transplantation or clinical trials. These data may be useful in characterizing the health care resource use and pharmacoeconomic impact of MDS in the United States.

Evolving classifications of the myelodysplastic syndromes

PURPOSE OF REVIEW

The classification of myelodysplastic syndrome is a continuously evolving process. Every new validated myelodysplastic syndrome classification reflects the better understanding of the disease, its pathogenesis and outcome. The proposed classifications attempt to create more homogenous subtypes of myelodysplastic syndrome, to better predict the prognosis and outcome.

RECENT FINDINGS

The myelodysplastic syndrome classifications evolved from the French-American-British to the WHO classification over the last few years. Several new studies validate the WHO classification. The International Prognostic Scoring System is very important to define patient risk of progression to acute myeloid leukemia and predict overall survival. Recent studies suggest International Prognostic Scoring System modifications and a group proposes a new WHO-based prognostic system.

SUMMARY

The WHO and International Prognostic Scoring Systems serve as tools to categorize patients in risk groups according to which the goal and type of treatment are different. The myelodysplastic syndrome classifications will continue to be reviewed and modified as we learn more about the disease to better perform this risk stratification.

Enhanced growth of myelodysplastic colonies in hypoxic conditions

OBJECTIVE

To determine the response of bone marrow progenitor cells from patients with myelodysplastic syndromes (MDS) to culture in physiologic oxygen tension.

METHODS

Methylcellulose progenitor assays using both unfractionated bone marrow mononuclear cells (MNCs) and purified CD34(+) progenitors were performed in atmospheric oxygen (18.6% O(2)) or one of two levels of hypoxia (1% and 3% O(2)). Assays were performed using normal donor marrow, MDS patient marrow, acute myelogenous leukemia marrow or peripheral blood blasts, chronic phase chronic myelogenous leukemia (CML) marrow MNCs, and blast crisis CML peripheral blood.

RESULTS

The majority of MDS samples showed decreased colony-forming units (CFU) in 18.6% O(2) compared to normal controls, as expected. However, in either 1% or 3% O(2), 9 of 13 MDS samples demonstrated augmentation of CFUs beyond that observed in normal controls, with 6 of 13 demonstrating a greater than ninefold augmentation. This effect is cell autonomous, as it persisted after purification of CD34(+) progenitor cells. Additionally, the augmented response to physiologic oxygen tension is specific to MDS, as it was not observed in either acute or chronic myelogenous leukemia samples.

CONCLUSION

These results suggest that the reported decrease in MDS CFUs reflects greater sensitivity of MDS progenitors or their progeny to the nonphysiologic oxygen tensions routinely used in vitro, rather than a true decrease in progenitor frequency. Importantly, these experiments for the first time describe an experimental system that can be used to study the growth of primary cells from patients with MDS.

Immunomodulation in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) - bone-marrow stem-cell malignancies that share pathogenetic overlap with acute myeloid leukemia - are characterized by peripheral-blood cytopenias and, in more advanced subtypes, varied degrees of maturation arrest. Premature apoptosis of bone-marrow cellular elements contributes to ineffective hematopoiesis, which is exacerbated by stromal production of inflammatory cytokines. Abrogation of the effects of these cytokines represents an area of active clinical research, particularly in the treatment of low-risk MDS. Agents such as thalidomide, lenalidomide, and infliximab have shown promising efficacy and tolerability in clinical trials, and may represent a springboard for future treatment combinations.

Who is WHO in myelodysplastic syndromes? Clinical implications of the WHO classification

Myelodysplastic syndromes (MDS) are a heterogeneous group of neoplastic clonal stem cell diseases characterized by dysplastic morphologic features with a varying percentage of leukemic blasts and clinical bone marrow failure. The French-American-British (FAB) system served as the gold standard of MDS classification for more than two decades. The World Health Organization (WHO) classification, built on the backbone of the FAB classification, is an attempt to further improve the prognostic value of MDS classification as well as to establish its clinical utility as a tool to select different treatments. In this article we highlight the major differences between the FAB classification and the WHO MDS classification. We discuss in more detail the experience of using the new WHO classification since its publication and review the studies that have tried to validate the prognostic value of the new classification or apply it to predict clinical responses to various treatments.

The myelodysplastic syndrome(s): a perspective and review highlighting current controversies

The myelodysplastic syndrome (MDS) includes a diverse group of clonal and potentially malignant bone marrow disorders characterized by ineffective and inadequate hematopoiesis. The presumed source of MDS is a genetically injured early marrow progenitor cell or pluripotential hematopoietic stem cell. The blood dyscrasias that fall under the broad diagnostic rubric of MDS appear to be quite heterogeneous, which has made it very difficult to construct a coherent, universally applicable MDS classification scheme. A recent re-classification proposal sponsored by the World Health Organization (WHO) has engendered considerable controversy. Although the precise incidence of MDS is uncertain, it has become clear that MDS is at least as common as acute myelogenous leukemia (AML). There is considerable overlap between these two conditions, and the former often segues into the latter; indeed, the distinction between AML and MDS can be murky, and some have argued that the current definitions are arbitrary. Despite the discovery of several tantalizing pathophysiological clues, the basic biology of MDS is incompletely understood. Treatment at present is generally frustrating and ineffective, and except for the small subset of patients who exhibit mild marrow dysfunction and low-risk cytogenetic lesions, the overall prognosis remains rather grim. In this narrative review, we highlight recent developments and controversies within the context of current knowledge about this mysterious and fascinating cluster of bone marrow failure states.

Evolving concepts in myelodysplastic syndromes

Myelodysplastic syndromes continue to be "a riddle, wrapped in a mystery inside of an enigma". Clearly, MDS represent a heterogeneous group of disorders, and no uniform etiology or treatment can be prescribed for all patients. This further underscores the need for MDS patients to be seen at specialized centers and placed on experimental protocols if they need treatment. The important thing to remember is that ultimately, the patient must remain the measure of all things, and must be given all the therapeutic choices including that of waiting and watching with supportive care alone. Recent biologic insights have expanded the therapeutic options, but no curative therapies except stem cell transplants are available at this time. By dissecting the biology and focusing efforts towards understanding the etiology of the cytopenias, significant therapeutic advances are being made in this disease. The momentum built up so far must not be lost now.

Epidemiological features of myelodysplastic syndromes: results from regional cancer surveys and hospital-based statistics

Although myelodysplastic syndromes (MDS) have been increasingly diagnosed in recent years, precise data on their prevalence and incidence are still lacking. Due to difficulties of diagnosis and classification, large-scale population-based studies that are required for obtaining truly representative data on the epidemiology of MDS are currently not available. Our present knowledge of the incidence and other epidemiological characteristics of MDS is based on a few regional studies performed by authors with a long-lasting interest in these hemopathies. Despite certain limitations, these studies have consistently shown that MDS are relatively common hematological malignancies. Their crude incidence varies from 2.1 to 12.6 cases per 100,000 people per year. Among the age group that is mainly affected, people older than 70 years, we are now faced with incidence rates of about 15 to 50 cases per 100,000 people per year. The recent increase in MDS incidence observed in some studies is probably not the result of an actual increase in the number of cases, but reflects improvements in geriatric medical care and diagnosis.

Growth characteristics of myelodysplastic CD34+ cells

Myelodysplastic syndromes (MDS) are a heterogeneous group of disorders of hematopoiesis entailing hyperproliferative and ineffective hematopoiesis associated with morphologic evidence of marrow cell dysplasia resulting in refractory cytopenia(s), and an increased risk of transformation into acute myeloblastic leukemia (AML). The administration of colony-stimulating factor(s) (CSFs) to patients with MDS increased blood neutrophil concentrations, in most patients, and it was anticipated to be of benefit to prevent infections. The progression to AML while being treated with CSFs has come under close scrutiny. In vitro studies are expected to produce more pertinent criteria for selection of patients who are likely to benefit, as well as the overall benefits of various therapies. For this purpose, in vitro colony assays are an excellent approach for investigation of the biologic characteristics of MDS progenitor cells. The stem cell phenotype CD34 is the one of the best markers of progenitor cells, and can be used for the purification of these cells to unify levels of maturation; a direct comparison of proliferative and differentiative capacity of MDS progenitor cells with normal CD34+ cells can thus be made. The properties of MDS CD34+ cells are described here in association with proliferation and differentiation, with special emphasis on the role of stem cell factor (a ligand for c-kit) in leukemic type growth of MDS CD34+ cells.

Increasing incidence of myelodysplastic syndromes: real or fictitious?

Over the past 10-20 years, there has been a growing interest in the myelodysplastic syndromes (MDS). Due to difficulties of diagnosis, classification and case recording, the epidemiological features of MDS are still poorly defined. Recently, a number of cancer registries have published data on the regional occurrence of MDS, suggesting that MDS are much more common than previously thought. The crude incidence of MDS in these studies was 3.5-12.6 per 100,000 population per year. In people over the age of 70 years, incidence rates varied between 15 and 50 per 100,000 per year. Contrary to the assumption of most hematologists, cancer surveys usually failed to demonstrate a rising incidence of MDS. In those studies showing a significant increase in MDS, the rising number of cases was probably due to increased physician awareness and extended use of invasive diagnostic procedures in elderly people. Differences in incidence figures between regional studies may be attributed to several causes, including regional variations in disease incidence, small and ill-defined reference populations, bias due to patient referral patterns, varying intensity of diagnostic procedures and different observation periods. Because of the paucity of clinical symptoms and insignificance of morphological bone marrow changes particularly in early stage MDS, the currently available incidence figures are likely to underestimate the true incidence of MDS. Large-scale epidemiological studies are required for obtaining truly representative statistics on the incidence and prevalence of the MDS. In industrialized countries, a dramatic increase in these disorders can be expected over the next few decades due to the 'greying' of the population.

A novel chromosomal abnormality involving chromosomes 2 and 18 in a patient with myelodysplastic syndrome

Cytogenetic analysis of bone marrow cells from a patient with myelodysplastic syndrome associated with eosinophilia showed a complex translocation with a 46,XY,t(2;18;2)(p23;q11;q32) karyotype. The patient has refractory anemia (RA) according to the French-American-British Cooperative Group (FAB) classification, and after 90 months of follow-up he shows no evidence of leukemic transformation. This chromosomal abnormality has not been previously described in myelodysplastic syndromes and may be associated with good prognosis as the patient has been stable for a long time.

The preleukemic syndrome: clinical and laboratory features, natural course, and management

The clinical and laboratory features of the stages in the evolution of acute nonlymphocytic leukemia are reviewed. Based on a retrospective analysis of 34 patients who died with an acute myelomonoblastic leukemia, the "preleukemic syndrome" has been shown to display a clinical picture sufficiently specific to permit its recognition prospectively (i.e., before the development of overt leukemia). The results to date of a variety of prospective studies are reviewed, and the approach(es) to the management of these cases is considered.

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 approximately 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.

Proliferation and differentiation of myelodysplastic CD34+ cells

Myelodysplastic syndromes (MDS) are a heterogeneous group of disorders of hematopoiesis involving hyperproliferative and ineffective hematopoiesis associated with morphologic evidence of marrow cell dysplasia resulting in refractory cytopenia(s), and an increased risk of transformation into acute myeloblastic leukemia (AML). The administration of colony-stimulating factor(s) (CSFs) to patients with MDS increased blood neutrophil concentrations, in most patients, and was also expected to be beneficial and to prevent infections. However, the progression to AML during the treatment with CSFs was suspected in some patients. Therefore, extensive in vitro studies were expected to lead to the establishment of criteria for selection of patients who are likely to benefit from CSF's as well as to establish the overall value of the different types of CSFs therapy. For this purpose, in vitro colony assays provide an excellent tool for investigating the biologic characteristics of MDS progenitor cells. However, conditions of the culture must be such that each progenitor can express its full potential for proliferation and differentiation. Because of the above, MDS progenitor cells cannot be used because they carry an impairment in proliferation and differentiation. To address this problem, one needs to know how many cells are being handled and the maximum numbers of colonies and clusters expected. CD34, a stem cell phenotype, is at present one of the best markers of progenitor cells, and can be used for purposes of purification. Using a defined number of CD34+ cells, it was feasible to make direct investigations on MDS progenitor cells. In this review the properties of MDS progenitor cells are described, in association with proliferation and differentiation, with special emphasis on the phenotypic subpopulations of MDS CD34+ cells.

Myelodysplastic syndromes in the elderly: the role of growth factors in management

Myelodysplastic syndrome (MDS) comprises a group of heterogeneous clonal bone marrow disorders leading to peripheral cytopenia(s) and hypercellular marrow in the majority of the patients. The morphology of the cell lines is characterized by dysplastic features in some or all cell lines. The FAB classification has divided MDS in five subgroups, namely (1) RA (refractory anemia); (2) RARS (refractory anemia with ring sideroblasts); (3) CMML (chronic myelomonocytic leukemia); (4) RAEB (refractory anemia with excess blasts); and (5) RAEB-T (refractory anemia with excess blasts in transformation). Myelodysplastic syndrome remains primarily a disease of the elderly. With a reported median age of 74.4 years, patients have a chronic relentless course with complication of cytopenias, and a significant number of MDS patients, especially from the RAEB and RAEB-T categories, end up in acute myeloid leukemic transformation. Cytogenetic abnormalities are present in 40-58% of the cases and can provide not only help in diagnosis, but also understanding regarding the clinical course and prognostic aspect. Management of MDS is quite pragmatic and at this stage far from satisfactory. Various modalities have included use of differentiating agents, aggressive chemotherapy, bone marrow transplant and, more recently, significant interest has been generated in the use of hematopoietic growth factors. Differentiating agent trials have been unrewarding so far; chemotherapy trials have resulted in less benefit and more early toxic deaths, especially in the elderly MDS patients where the disease predominates. Bone marrow transplant appears suitable for some patients who are at a younger age. Salvation from this disease is being searched in the proper usage of hematopoietic growth factors and cytokines. There has been concern, however, that usage of growth factors has led to early and enhanced transformation of these patients to frank acute leukemic states. This concept appears to be somewhat refuted by newer controlled trials with GM-CSF and G-CSF, emphasizing that the acute leukemic transformation is the natural course of the disease and is not hastened by growth factor use. Preliminary studies are also suggesting that a combination of growth factors, especially G-CSF and erythropoietin as compared to chemotherapies, could be more beneficial in prolonging the survival of MDS patients who have progressed to the acute leukemic phase. More studies are needed for the understanding of the pathogenetic mechanism(s) in order to facilitate a more suitable and appropriate management strategy for MDS.

Myelodysplasia. The clinical spectrum of 51 patients

BACKGROUND

Over a 15 year period, the authors followed 51 male patients with myelodysplastic syndromes whose clinical findings, laboratory data, and evolution demonstrated a wide spectrum of disease.

METHODS

The following characteristics were assessed: age at diagnosis, risk factors, clinical presentation, laboratory features, category of myelodysplasia, leukemic conversion, and overall survival.

RESULTS

The clinical manifestations included hemolytic episodes in two patients, antibody-mediated thrombopenia in one, marked marrow fibrosis in two; thrombocytosis in three, and simultaneous lymphoproliferative disorders in two. There were 21 patients whose marrow was either normo- or hypocellular. Six patients presented with single cytopenia but not anemia. There were six instances of overlapping of the French-American-British classification. Eighteen patients progressed to acute leukemia and 1 to chronic myelomonocytic leukemia.

CONCLUSIONS

These observations indicate that patients with myelodysplastic syndromes may have single cytopenia without anemia that progresses to acute leukemia and may, rarely, evolve into chronic myelomonocytic leukemia. The clinical aspects of these syndromes may include autoimmune phenomena and myeloproliferative features.

Proliferation and differentiation of myelodysplastic CD34+ cells in serum-free medium: II. Response to combined colony-stimulating factors

To investigate the role of colony stimulating factors (CSFs) in the proliferation and differentiation of progenitor cells from myelodysplastic syndromes (MDS), marrow progenitor cells from 18 MDS patients were highly purified using CD34 monoclonal antibody and immunomagnetic microspheres (MDS CD34+ cells). These cells were cultured in serum-free medium with various combinations of five colony stimulating factors (CSFs): recombinant human interleukin-3 (rIL-3), granulocyte/macrophage-CSF (rGM-CSF), granulocyte-CSF (rG-CSF), macrophage-CSF (rM-CSF), and erythropoietin (rEP). Among the tested CSFs, such as rM-CSF, rG-CSF, rGM-CSF and rIL-3, a combination of the first three CSFs was the most effective stimulus for the proliferation of non-erythroid MDS progenitor cells. An increase of undifferentiated "blast" cell colonies in 5/18 MDS patients occurred and these 5 patients belonged to the high-risk group. In the presence of these three CSFs, rIL-3 had no effect on the proliferation and differentiation of MDS CD34+ cells; however, IL-3 was efficient for the proliferation of MDS CD34+ cells to the erythroid lineage. rGM-CSF or rIL-3 alone did not efficiently support proliferation and differentiation of CD34+ cells. M-CSF is present in normal human serum at a concentration of 550 +/- 110 U/ml, a concentration exceeding that used in this study (100 U/ml). Therefore, in vivo administration of G-CSF combined with GM-CSF to MDS patients may be one of the most effective CSF combinations for proliferation of MDS progenitor cells to the non-erythroid lineage. However, the effect on the capacity for differentiation was minimal, especially in patients belonging to the high-risk group.

Epidemiological and etiological aspects of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are increasingly recognized as a cause of bone marrow failure, and are at least as frequent as acute myeloid leukemias. While the overall incidence is about 2-4/100,000/year, incidence figures rise steeply with age. Incidence rates of 20-30/100,000/year in persons over 70 demonstrate that MDS are among the most common hematological neoplasias in this age group. However, due to difficulties of diagnosis and classification, patient registration in population-based registers is far from complete. As a prerequisite for truly representative statistics, future revisions of disease classification systems must incorporate MDS as a separate group of disorders. The difficulties in conducting epidemiological studies also impede the identification of risk factors for the development of MDS. Current knowledge of occupational risk factors is also reviewed here. More rapid progress in our understanding of MDS may come from recent advances in methodology that have begun to shed some light on the cytogenetic and molecular aspects of leukemogenesis in general, and MDS in particular. Non-random chromosomal changes can be found in about 50% of cases at diagnosis, but they are probably late events in the evolution of MDS, reflecting the progressive genomic instability of the premalignant clone. Proto-oncogene mutations have also been suggested to be relevant to the pathogenesis of MDS, but longitudinal studies of point mutations of the N-ras proto-oncogene revealed that such events, although often associated with rapid deterioration and transformation to AML, also appear to be late events during the course of disease. Therefore, it remains a major challenge to identify those lesions that initiate the multistep development of preleukemia. As the incidence of MDS correlates strongly with age, it is reasonable to presume that age-dependent changes of the hematopoietic system may play a role in the initiation of MDS. Aging is probably associated with a compromised marrow reserve through reduction in the size of the stem cell pool. Through increased proliferative activity, the remaining stem cells may be particularly vulnerable to mutagenic insults. Immunological attack on stem cells, mitochondrial DNA mutations, and the regulatory influence of the hematopoietic microenvironment must also be considered as possibly contributing to the early stages of MDS.

Cutaneous involvement in chronic myelomonocytic leukemia

BACKGROUND

Chronic myelomonocytic leukemia has been associated with various nonspecific cutaneous manifestations. Rarely has the leukemia been reported to directly affect the skin.

METHODS

This case documents the progression of a patient who ultimately developed chronic myelomonocytic leukemia, by clinical examination, hematologic parameters, dermatopathology, and bone marrow pathology.

RESULTS

The skin showed nonspecific cutaneous involvement, progressing to specific leukemic lesions parallel with increasing systemic and hematologic involvement.

CONCLUSIONS

Chronic myelomonocytic leukemia can manifest with lesions of leukemia cutis. The possibility of nonspecific cutaneous involvement in the preleukemic phase exists.

Impaired proliferation and differentiation of myelodysplastic CD34+ cells

The myelodysplastic syndromes (MDS) are a heterogeneous group of disorders of hematopoiesis entailing hyperproliferative and ineffective hematopoiesis resulting in refractory cytopenia(s), and increased risk of transformation into acute myeloblastic leukemia (AML). The widely used classification defined by the French-American-British group (FAB) recognizes 5 cytological subtypes of different prognosis, based essentially on the presence and the frequency of marrow blasts. The percentage of marrow blasts does not exceed 30%, hence, direct investigations of biological and biochemical events of MDS blast cells have been hampered. The CD34 antigen is currently unique in its narrow specificity of expression on human lymphohematopoietic progenitor cells. This cell membrane phosphoglycoprotein has been used for immunologic blast cell purification, notwithstanding the frequency of marrow blasts, and has provided a set of tools for investigations of MDS i.e. a direct comparison of the nature of blast cells in each of the MDS subtypes, using immunologic, biologic, biochemical and molecular biological methodology. A combination of serum-free medium and a purification method for blast cells provided evidence that the progenitor cell growth abnormalities in these disorders involve a defect in the capacity of progenitor cells to respond to stimulation with growth factor(s), and has presented direct evidence for the manner in which myelodysplastic CD34+ cells are impaired.

Erythroblasts as an index of initial stage of 2,7-FAA, ENU and BNU-induced rat leukemia

The appearance of orthochromatic erythroblasts in the peripheral blood was evaluated as an index of the initial stage of leukemia induced in rats by the oral administration of N,N'-2,7-fluorenylenebisacetamide, 1-ethyl-1-nitrosourea and 1-butyl-1-nitrosourea. Solitary leukemia lesions found mainly in the bone marrow and composed of one or a few nodular foci were found by using erythroblasts as an index. The time interval from the first appearance of erythroblasts to autopsy was short in solitary lesions, slightly longer in scattered lesions, and even longer in diffuse leukemia lesions. Although the appearance of orthochromatic erythroblasts in the peripheral blood was due to several causes other than leukemia, this appearance was useful as an index of the initial stage of chemically induced leukemia in rats.

Proliferation and differentiation of myelodysplastic CD34+ cells in serum-free medium: response to individual colony-stimulating factors

The presence of serum or contaminant cells may alter clonal development of haematopoietic progenitor cells in vitro. To investigate the pathogenesis of myelodysplastic syndromes (MDS), marrow progenitor cells from 13 MDS patients were highly purified using monoclonal antibodies including CD34 and immunomagnetic microspheres. The cells positive for CD34 in the purified cells were in the range from 87% to 98%. These purified cells were cultured in serum-free medium with individual colony stimulating factors (CSFs) to investigate whether CD34+ cells from MDS patients have abnormal responses to individual CSFs. Dose response experiments with the purified CD34+ cells and recombinant human macrophage-CSF (rM-CSF), granulocyte-CSF (rG-CSF), granulocyte/macrophage-CSF (rGM-CSF), interleukin-3 (rIL-3) or erythropoietin (rEP) were performed in serum-free fibrin clots in 11 patients. Five patients showed a diminished response to rG-CSF and one patient to rEP. In the remaining six patients the purified CD34+ cells did not respond to a stimulation of any individual CSFs. The results indicate that the progenitor cell growth abnormalities in these disorders involve a defect in the capacity of progenitor cells to respond to stimulation with G-CSF, and present direct evidence for the manner in which myelodysplastic CD34+ cells are impaired.