Myelodysplastic syndrome or MDS

Myelodysplasia refers to a set of syndromes (also called myelodysplastic syndromes, or MDS) in which the normal process of making mature blood cells (red blood cells, white blood cells, and platelets) – known as hematopoiesis – is impaired.  Hematopoiesis begins with a hematopoietic stem cell (HSC) present in the bone marrow. The HSC is capable of differentiating into two more specialized stem cells: lymphoid stem cells and myeloid stem cells. Lymphoid stem cells differentiate into a type of white blood cell called a lymphocyte, while myeloid stem cells can differentiate into red blood cells, platelets, and a group of white blood cells called granulocytes and monocytes. In myelodysplasia, the stem cells do not differentiate completely; they remain as immature “blast cells” instead of maturing into normal red blood cells, white blood cells and platelets. This results in a disproportionately low number of healthy mature blood cells, a condition known as cytopenia. When there is a shortage of red blood cells, this is called anemia. The corresponding deficiencies in the other cell types are called leukocytopenia (white blood cells) and thrombocytopenia (platelets).  Each of these deficiencies is associated with a host of health problems such as bleeding (caused by low platelet counts) and infection (due to low white blood cell counts). Besides the effects caused by a deficiency of normal blood cells, myelodysplasia often produces increased numbers of immature blast cells in the bone marrow. The accumulation of excess blast cells may result in some of the blasts becoming abnormal (their morphology, or form, is defective). This process is known as malignant transformation, and leads to leukemia. Hence, myelodysplasia is often considered to be a premalignant, or preleukemic condition, necessitating careful monitoring and intervention.    Myelodysplasia Symptoms Myelodysplastic syndromes often do not cause early symptoms and are sometimes found during a routine blood test. Although the symptoms below may be indicative of myelodysplasia, other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur: Shortness of breath Weakness or feeling tired Pallor (pale skin) Easy bruising or bleeding Petechiae (flat, pinpoint spots under the skin caused by bleeding) Fever or frequent infections Splenomegaly (enlargement of the spleen)  Diagnosing Myelodysplasia Since myelodysplastic syndromes, or MDS, are diseases of blood and bone marrow, careful analysis of both is critical. Complete Blood Count (CBC) The CBC often provides the first signs that a patient has MDS by revealing unusually low levels of certain types of blood cells. A CBC measures the following: The number of red blood cells and platelets The number and type of white blood cells The amount of hemoglobin (the protein that carries oxygen) in the red blood cells The portion of the blood sample made up of red blood cells (called the hematocrit) Peripheral blood smear This is a procedure in which a sample of blood is checked for changes in the number, type, shape and size of blood cells, and for too much iron in the red blood cells. Bone Marrow Aspiration and Biopsy Knowing how many blasts are in the bone marrow is important to accurately diagnose the type of MDS the patient has. Therefore, a bone marrow aspirate and biopsy are necessary. For this procedure, a needle is inserted into the hipbone or sternum to obtain a small piece of bone and sample of bone marrow, which are then analyzed under the microscope. Cytogenetic Studies In cytogenetic studies, the bone marrow cells are examined for specific chromosomal abnormalities. The presence or absence of these markers can serve as a guide to prognosis and treatment.