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The myelodysplastic syndromes (MDS, formerly known as preleukemia) are a diverse collection of hematological (blood-related) medical conditions that involve ineffective production (or dysplasia) of the myeloid class of blood cells.
The myelodysplastic syndromes are all disorders of the stem cell in the bone marrow. In MDS, hematopoiesis (blood production) is disorderly and ineffective. The number and quality of blood-forming cells decline irreversibly, further impairing blood production.
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The median age at diagnosis of a MDS is between 60 and 75 years; a few patients are younger than 50; MDS diagnoses are rare in children. Males are slightly more commonly affected than females.
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Signs and symptoms are nonspecific and generally related to the blood cytopenias:
Anemia(low RBC count or reduced hemoglobin) —chronic tiredness, shortness of breath, chilled sensation, sometimes chest pain
Neutropenia (low neutrophil count) —increased susceptibility to infection
Thrombocytopenia (low platelet count) —increased susceptibility to bleeding and ecchymosis (bruising), as well as subcutaneous hemorrhaging resulting in purpura or petechia
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This bone marrow film demonstrates an almost complete replacement of normal hematopoiesis by blasts in a refractory anemia with an excess of blasts in transformation. Note the signs of abnormal maturation such as vacuolation, double nucleus, and macrocytosis.
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In about one third of patients with MDS, the disease transforms into acute myelogenous leukemia (AML), usually within months to a few years.
Although there is some risk for developing acute myelogenous leukemia, about 50% of deaths occur as a result of bleeding or infection. Leukemia that occurs as a result of myelodysplasia is notoriously resistant to treatment.
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MDS must be differentiated from anemia, thrombocytopenia, and/or leukopenia. Usually, the elimination of other causes of these cytopenias, along with a dysplastic bone marrow, is required to diagnose a myelodysplastic syndrome.
A typical investigation includes:
Full blood count and examination of blood film. The blood film morphology can provide clues about hemolytic anemia, clumping of the platelets leading to spurious thrombocytopenia, or leukemia.
Bone marrow examination by a hematopathologist. This is required to establish the diagnosis, since all hematopathologists consider dysplastic marrow the key feature of myelodysplasia.
Cytogenetics or chromosomal studies. This is ideally performed on the bone marrow aspirate.
Flow cytometry is helpful to establish the presence of any lymphoproliferative disorder in the marrow.
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Supportive therapy, including transfusions of the cells that are deficient (red blood cells, platelets). Bone marrow transplantation.
Cytotoxic chemotherapy is used in patients with MDS with increasing myeloblasts and those who have progressed to acute leukemia.
Drugs
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A risk factor is anything that changes your chance of getting a disease.
-Prior treatment with chemotherapy is the most important risk factor for MDS. Patients who have been treated with certain chemotherapy drugs for cancer are more likely to develop MDS.
-Some of the drugs that can lead to MDS include:
Genetic syndromes - Some bone marrow problems are caused by abnormal (mutated) genes. People with certain inherited syndromes are more likely to develop MDS.
Familial MDS - In some families, MDS has been found to occur more often than would be expected.
Smoking
Environmental exposures - Environmental risk factors, such as radiation and certain chemicals,
Age - The risk of MDS increases with age. This disease is rare in people younger than 40, with most cases found in those older than 60.
Sex - MDS is more common in men.