Issues in the Pathology of the Myelodysplastic Syndromes

Involvement of transforming growth factor-β and thrombopoietin in the pathogenesis of myelodysplastic syndrome with myelofibrosis

We investigated the cause of myelofibrosis and proliferation of megakaryocytes in myelodysplastic syndrome with myelofibrosis (MDS-MF (+)). Plasma-transforming growth factor-beta1 (PTGF-beta1) concentrations closely correlated with myelofibrosis grade in MDS-MF (+) and were higher than those in idiopathic myelofibrosis (IMF), essential thrombocythemia (ET), idiopathic thrombocytopenic purpura (ITP), MDS-without MF (MDS-MF (-)) or healthy volunteers (HV). Peripheral blood mononuclear cells from MDS-MF (+) patients expressed more TGF-beta1 mRNA than those from IMF, MDS-MF (-) or HV. When we immunostained bone marrow specimens of MDS-MF (+) for TGF-beta, the intensity of blasts was apparently higher than that of megakaryocytes, while in MDS-MF (-), megakaryocytes were immunostained with a similar intensity as that in MDS-MF (+), but blasts were negative for staining. In IMF, megakaryocytes, monocytes and small mononuclear cells representing CD34+ cells were all similarly stained with a much lower intensity than that of blasts in MDS-MF (+). The number of bone marrow megakaryocytes were increased the most in MDS-MF (+), followed by ET, ITP, MDS-MF (-) and NHL and correlated with plasma thrombopoietin (TPO) levels or with plasma TGF-beta1 levels, respectively, in each disease. Thus, in MDS-MF (+), both myelofibrosis and the increased megakaryocytes were ascribed to overproduction of TGF-beta1 from blasts.

Clonal cytogenetic abnormalities in bone marrow specimens without clear morphologic evidence of dysplasia: a form fruste of myelodysplasia?

Cytogenetic abnormalities suggestive of a myeloid disorder are occasionally observed in the bone marrow (BM) cells of patients with morphologically and immunohistochemically unremarkable marrow aspirates and biopsies. Between 1994 and 2000, 55 such patients were seen at our institution (34 men; median age of 66 years). The indications for BM sampling included unexplained cytopenias (31 patients), staging or follow-up of a lymphoproliferative disorder or a plasma cell dyscrasia (18 patients), or another miscellaneous reason (6 patients). Specific cytogenetic abnormalities included a 20q deletion or monosomy 20 (10 patients), a chromosome 7 deletion (8 patients), +8 (5 patients), del(5q) or a 5q translocation (4 patients), and del(13q) (2 patients). Eleven patients had a complex karyotype. As of January 2002, 23 of the 55 patients were dead; median follow-up for living patients is 20 months. Of the 23 dead patients, 1 died of acute myelogenous leukemia (AML) and 6 of complications related to cytopenias. This study provides support for obtaining cytogenetic studies in patients with unexplained cytopenias if a morphologic explanation for the cytopenias is lacking. Continued follow-up of this heterogeneous cohort and further studies of similar patients will more clearly define the disease processes and prognosis for this constellation of laboratory findings.

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.

Diagnostic utility of flow cytometric immunophenotyping in myelodysplastic syndrome

The myelodysplastic syndromes (MDSs) are characterized by bilineage or trilineage dysplasia. Although diagnostic criteria are well established for MDS, a significant number of patients have blood and bone marrow findings that make diagnosis and classification difficult. Flow cytometric immunophenotyping is an accurate and highly sensitive method for detection of quantitative and qualitative abnormalities in hematopoietic cells. Flow cytometry was used to study hematopoietic cell populations in the bone marrow of 45 patients with straightforward MDS. The results were compared with those obtained in a series of patients with aplastic anemia, healthy donors, and patients with a history of nonmyeloid neoplasia in complete remission. The immunophenotypic abnormalities associated with MDS were defined, and the diagnostic utility of flow cytometry was compared, with morphologic and cytogenetic evaluations in 20 difficult cases. Although morphology and cytogenetics were adequate for diagnosis in most cases, flow cytometry could detect immunophenotypic abnormalities in cases when combined morphology and cytogenetics were nondiagnostic. It is concluded that flow cytometric immunophenotyping may help establish the diagnosis of MDS, especially when morphology and cytogenetics are indeterminate. (Blood. 2001;98:979-987)

Biologic characteristics of patients with hypocellular myelodysplastic syndromes

Rates of proliferation and apoptosis as well as expression of tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta) and the number of macrophages were measured in bone marrow (BM) biopsies of 33 patients who presented with hypocellular (cellularity < 30%) myelodysplastic syndromes (MDS). Results showed that 2/3 of the patients had high apoptosis, high cytokine levels and large number of macrophages in their biopsies while 1/3 did not. Apoptosis and TNF-alpha levels were directly related (r = 0.583, P = 0.003, n = 24) as was apoptosis and the degree of anemia (P = 0.033, n = 18). A subgroup of patients with abnormalities of chromosomes 5 or 7 had higher platelets (P = 0.026) and higher apoptosis (P = 0.038) when compared with the rest of the group. Eight patients had no evidence of apoptosis and almost no detectable TNF-alpha in their biopsies. We conclude that within the hypocellular variant of MDS, there may be two distinct sub-groups of patients, one who present with high cytokine-mediated intramedullary apoptosis and the other who may be better characterized as having a stem-cell failure defect since they showed no evidence of apoptosis.

Myelodysplastic syndrome: a search for minimal diagnostic criteria

We have evaluated dyshemopoietic features in bone marrow (BM) samples obtained from healthy people aged over 50 without peripheral blood (PB) cytopenia patients and compared them with MDS patients. Control group displayed BM features of dyserythropoiesis and dysgranulopoiesis in up to 15 and 27% of the considered cell elements (P90) respectively, overlapping in part with MDS patients. Interobserver agreement in dyshemopoietic features was highest for BM blast cell and pathological sideroblast counts. An algorithm based on BM blast cell and pathological sideroblast counts that has been verified on 613 patients from different Spanish centers may be of help to improve reproducibility in Myelodysplastic syndrome (MDS) diagnosis.

Practical aspects in the diagnosis and management of aplastic anemia

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

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.

Bone marrow pathology in relapsing polychondritis: high frequency of myelodysplastic syndromes

Haemopathologic changes were studied in 19 patients (13 male, six female, age 33-85 years, mean 56 years) with relapsing polychondritis (RP). Anaemia was found in eight, thrombocytopenia in two and splenomegaly in three patients. A total of 17 bone marrow biopsies were obtained from seven individuals. Bone marrow evaluation revealed myelodysplastic syndromes (MDS) with marked trilineage hyperplasia and dysplasia in three cases. Since an excess of myeloblasts or an increase of CD34 positive progenitor cells was not seen, the disorders were designated as 'refractory anaemia' or with regard to the dysplastic megakaryopoiesis 'MDS, unclassifiable'. Two of the three patients died after 10 and 55 months of follow-up due to infectious complications. In a further patient, bone marrow analysis repeatedly showed an unexplained granulopoietic hyperplasia, which, however, was not dysplastic enough to allow a diagnosis of MDS. The remaining patients had clearly reactive changes. Our findings support the notion that RP is a heterogenous disorder and suggest that RP may at times represent a paraneoplastic phenomenon of an underlying MDS. Since HLA typing revealed a significantly increased frequency of the antigen DR4 (10/17 patients positive = 59%), we hypothesize that immunological imbalances due to the MDS in conjunction with a specific immunogenetic background may play key roles in the pathogenesis of RP in these patients.

An isochromosome of the long arm of chromosome 18 in a patient with myelodysplastic syndrome with myelofibrosis

A case of myelodysplastic syndrome (MDS) with myelofibrosis and i(18q) is reported. The patient, a 29-year-old Chinese man, was noted to be anemic over a 10-year period. Recently, his spleen became progressively massive and bone marrow aspirates yielded "dry taps" on several occasions. Hematologic investigation disclosed pancytopenia, numerous nucleated red cells, and slightly increased myeloblasts (8%) in the peripheral blood. Bone marrow aspirate and biopsy revealed hypercellular marrow, trilineage dysplasia, and significant reticulin fibrosis, but without collagen formation. Bone marrow karyotypic analysis with R-banding showed an isochromosome 18q as a sole abnormality in 20 of 24 metaphases analysed. The patient died of severe anemia and bleeding due to bone marrow failure. We believe that i(18q) and myelofibrosis may be related to his poor prognosis.

Myelodysplastic syndromes in childhood--classification, epidemiology, and treatment

Much of the applied terminology of myelodysplastic syndromes (MDS) in childhood is confusing and not mutually exclusive. It is therefore proposed that the FAB classification of MDS is used in children in order to improve diagnostic precision and to facilitate epidemiologic, clinical, and therapeutic comparisons. The true incidence of childhood MDS is unknown but the rate may approximate the incidence of acute myelogenous leukemia. A pooled analysis of eight larger series representing 110 children less than 15 years old at diagnosis with de novo MDS classified according to the FAB recommendations showed that the more aggressive subtypes dominated, which partly may reflect that the less advanced cases are underdiagnosed. The median age at presentation was 6.0 years. The male/female ratio was 1.6. Monosomy 7 was the most frequent cytogenetic abnormality. The median survival was 13 months and the probability of survival three years from diagnosis was 16%. Spontaneous remission may be observed very infrequently. Allogeneic bone marrow transplantation (BMT) represents the only potentially curative treatment. The survival rate three years after BMT is about 50%. Major differences between childhood and adult MDS exist with respect to the distribution of FAB subgroups, the rate of progression, and the cytogenetic findings. The literature on MDS in children is still sparse and there is an obvious need for more studies designed to determine the incidence, clinical and laboratory characteristics, the natural course, and the efficacy of contemporary treatment options.