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Myelodysplastic Syndrome (MDS)
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Preleukemia, hemopoietic dysplasia
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- Bone marrow is spongy, cell-rich tissue in the bones that is the site in the body where red blood cells (RBC), white blood cells (WBC), and platelets are generated and mature into normal, functioning cells. RBC carry oxygen to the cells of the body, WBC fight infection, and platelets assist in blood clotting.
- In Myelodysplastic Syndrome (MDS), these cells are unable to mature normally. Known as blast cells, an abnormal increase in the number of these immature cells interferes with the normal production and maturation of WBC, RBC, and platelets.
- Such a lack in the production of mature cell types may lead to serious problems. Individuals with MDS have anemia, low platelets, and a decrease in neutrophiles (cells that fight infection). MDS is a chronic disease that progresses to acute myeloid Leukemia in many
cases -- with more severe symptoms that present rapidly, causing bleeding, infections, and severe anemia.
- There are 5 types of MDS, classified according to the percentage and nature of the blast cells present in the blood and the bone marrow. These subgroups are as follows:
- Refractory Anemia (RA) -- less than 1 % blast cells in the blood, and less than 5% in bone marrow.
- Refractory Anemia
with ringed sideroblasts (RAS) -- less than 5% blast cells in marrow, less than 1 % in the blood, and greater than 15% ringed sideroblasts. (Ringed sideroblasts are caused when iron is unable be used normally in forming hemoglobin (i.e., the oxygen-carrying molecule in RBC), appearing under microscope as ring-shaped iron deposits attached to immature blast cells.
- Refractory Anemia
with excess blasts (RAEB) -- currently considered to be acute myeloid Leukemia (AML), characterized by the presence of 5-20% blasts in the marrow, and less than 5 % in the blood.
- Refractory Anemia
with blasts in transformation (RAEB-t) -- defined by 20-30% blasts in marrow; and presenting Auer bodies (rodlike structures seen in the cytoplasm of blasts in Leukemia) under microscope.
- Chronic myelomonocytic Leukemia (CMML) --
less than 55% blast cells in the blood, and 5-20% in the marrow. The major increase is seen in a cell type called a monocyte, used to fight bacteria under normal conditions.
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- Bruising
- Abnormal bleeding from minor cuts
- Nose bleeds
- Fatigue
- Shortness of breath
- Lightheadedness
- Paleness
- Bacterial Infections that do not resolve with antibiotics
- Feeling of fullness in left upper abdomen (enlarged spleen), especially in those with CMML
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- Unknown
- Mutations of certain genes may be a factor-most commonly involved are chromosomes 5 and 7.
- The MDS diseases are not inherited (not passed down from parent to child).
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- Often discovered in the course of routine physical examination, presenting an enlarged spleen (splenomegaly), swollen lymph glands, and unexplained Bruising.
- The patient is then referred to a blood specialist (hematologist).
- The doctor may examine a blood smear from the patient under a microscope, looking for abnormal cell types and their number.
- Blood tests may reveal anemia (low RBC), thrombocytopenia (low platelets), or low WBC count.
- A bone marrow sample can be obtained (by aspiration), either from the hip or breastbone area, and can confirm the diagnosis of MDS.
- Cytogenetic testing can show chromosomal abnormalities in some MDS patients.
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- Gasoline and benzene exposure
- Radiation therapy
- Chemotherapy with alkylating agents
- Most cases are seen in those over age 55.
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- Treatment depends on the type of MDS, the patient's age and general health
- It is often supportive, involving --
- Transfusion of blood for anemia or bleeding. With repeated transfusions there is a risk of iron overload (accumulates and damages certain organs) requiring iron chelation therapy
- Platelet transfusion
- Antibiotic for infections
- Immunization against flu, pneumococcal Pneumonia, and hepatitis is often administered.
- Vitamins (i.e., A & D) and good nutritional (low in iron) practices may be recommended.
- Chemotherapy aims to kill the leukemic cells.
- Biological therapy stimulates the body's natural defenses to fight against MDS. G-CSF (granulocyte-colony stimulating factor) and EPO (stimulates RBC growth) is one such therapy that may be used in combination with others, such as chemotherapy. Other growth factors are being developed to help increase the number of other blood cell types (e.g., macrophages, platelets, etc.).
- Bone marrow transplant is especially effective in those under the age of 50. The only drawback is in finding donors to match the recipient's blood type.
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