A myelodysplastic syndrome (MDS) is one of a group of cancers in which immature blood cells in the bone marrow do not mature, so do not become healthy blood cells.[3] Early on, no symptoms typically are seen.[3]Later, symptoms may include feeling tired, shortness of breath, bleeding disorders, anemia, or frequent infections.[3] Some types may develop into acute myeloid leukemia.[3]
Risk factors include previous chemotherapy or radiation therapy, exposure to certain chemicals such as tobacco smoke, pesticides, and benzene, and exposure to heavy metals such as mercury or lead.[3] Problems with blood cell formation result in some combination of low red blood cell, platelet, and white blood cell counts.[3] Some types have an increase in immature blood cells, called blasts, in the bone marrow or blood.[3] The types of MDS are based on specific changes in the blood cells and bone marrow.[3]
Treatments may include supportive care, drug therapy, and hematopoietic stem cell transplantation.[3]Supportive care may include blood transfusions, medications to increase the making of red blood cells, and antibiotics.[3] Drug therapy may include the medications lenalidomide, antithymocyte globulin, and azacitidine.[3]Certain people can be cured with chemotherapy followed by a stem-cell transplant from a donor.[3]
About seven per 100,000 people are affected, with about four per 100,000 people newly acquiring the condition each year.[4] The typical age of onset is 70 years.[4] The outlook depends on the type of cells affected, the number of blasts in the bone marrow or blood, and the changes present in the chromosomes of the affected cells.[3] The typical survival time following diagnosis is 2.5 years.[4] The conditions were first recognized in the early 1900s.[5] The current name came into use in 1976.[5]
| Myelodysplastic syndrome | |
|---|---|
| Other names | Preleukemia, myelodysplasia[1][2] |
 | |
| Blood smear from a person with myelodysplastic syndrome. A hypogranular neutrophil with a pseudo-Pelger-Huet nucleus is shown. There are also abnormally shaped red blood cells, in part related to removal of the spleen. | |
Signs and symptoms[edit]
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[6]
- Neutropenia (low neutrophil count) – increased susceptibility to infection[7]
- Thrombocytopenia (low platelet count) – increased susceptibility to bleeding and ecchymosis (bruising), as well as subcutaneous hemorrhaging resulting in purpura or petechiae[8][9]
Many individuals are asymptomatic, and blood cytopenia or other problems are identified as a part of a routine blood count:[10]
- Neutropenia, anemia, and thrombocytopenia
- Splenomegaly or rarely hepatomegaly
- Abnormal granules in cells, abnormal nuclear shape and size
- Chromosome abnormality, including chromosomal translocations and abnormal chromosome number
Although some risk exists for developing acute myelogenous leukemia, about 50% of deaths occur as a result of bleeding or infection. However, leukemia that occurs as a result of myelodysplasia is notoriously resistant to treatment. Anemia dominates the early course. Most symptomatic patients complain of the gradual onset of fatigue and weakness, dyspnea, and pallor, but at least half the patients are asymptomatic and their MDS is discovered only incidentally on routine blood counts. Previous chemotherapy or radiation exposure is an important factor in the person's medical history. Fever and weight loss should point to a myeloproliferative rather than myelodysplastic process.[citation needed]
Cause[edit]
Some people have a history of exposure to chemotherapy (especially alkylating agents such as melphalan, cyclophosphamide, busulfan, and chlorambucil) or radiation (therapeutic or accidental), or both (e.g., at the time of stem cell transplantation for another disease). Workers in some industries with heavy exposure to hydrocarbons such as the petroleum industry have a slightly higher risk of contracting the disease than the general population. Xylene and benzene exposures have been associated with myelodysplasia. Vietnam veterans exposed to Agent Orange are at risk of developing MDS. A link may exist between the development of MDS "in atomic-bomb survivors 40 to 60 years after radiation exposure" (in this case, referring to people who were in close proximity to the dropping of the atomic bombs in Hiroshima and Nagasaki during World War II).[11] Children with Down syndrome are susceptible to MDS, and a family history may indicate a hereditary form of sideroblastic anemia or Fanconi anemia.[citation needed]
https://en.wikipedia.org/wiki/Myelodysplastic_syndrome
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