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(A) etiology
Not understand the pathogenesis of MDS, suggesting that due to biological, chemical, or physical factors such as gene mutations, chromosomal abnormalities to a clonal proliferation of malignant cells, has been recognized mutagens such as viruses, certain drugs (such as chemotherapy drugs) , radiation (radiotherapy), industry reaction agent (such as benzene, polyethylene) and environmental pollution can be carcinogenic, mutagenic agents can cause chromosomal rearrangements or gene rearrangement, it may only cause a change in gene expression in MDS , but in cell culture, cytogenetics, molecular biology and clinical studies have confirmed, MDS is a derived hematopoietic stem / progenitor cell level of clonal disease, its causes and leukemia similar to the present have shown that at least 2 lymphocytes and malignant diseases
Category (a) cause categories can be divided into primary and secondary health (secondary to long-term chemotherapy, radiotherapy, or secondary to cancer, autoimmune disease, etc.) (b) morphological classification of hematology and bone marrow morphology according to characteristics, FAB MDS Cooperative Group will be divided into 5 types, various features are as follows: 1. refractory anemia (RA) mostly occurs in elderly patients aged over 50, the main clinical, anemia, decreased reticulocytes, peripheral blood neutrophil and platelet are mostly reduced. Peripheral blood progenitor cells rare, not more than 1%. Proliferation of normal b


one marrow cells or hyperactivity, and more obvious erythroid hyperplasia, a rare ring sideroblasts, red blood cell morphological abnormalities more common. Granulocyte and megakaryocyte has some form of abnormal cells, but usually less severe. The original bone marrow
Abnormal cells in hematopoietic stem cells no more than 5%. 2. Refractory anemia with ring sideroblasts granulocyte (RAS) This group of patients with RA appears the main difference is that the ring sideroblasts, bone marrow nucleated red blood cells account for more than 15%. The majority of white blood cells and platelet count normal, serum ferritin concentration increased. 3. Refractory anemia with blasts (RAEB) patients were older, most of them in 50 years of age. Most three-line cells in peripheral blood were reduced to varying degrees, a few cases only two lines were reduced. Three-line cells were markedly abnormal. Peripheral blood progenitor cells often appear, but no more than 5%. Primitive bone marrow cells between 5% to 20%. Immature myeloid and erythroid cells increased, significant morphological changes. 4. Chronic myelomonocytic leukemia (CMML) are more seen in the elderly. Liver, splenomegaly common. Anemia and thrombocytopenia. The main feature is more blood and bone marrow mononuclear cells. Peripheral blood mononuclear cells in the absolute number of 1 109 / L, often accompanied by an increase in neutrophils, and morphologic abnormalities. Primitive cells in peripheral blood of less than 5%. Bone marrow cell proliferation was significantly increased grain: red ratio increased, the original cells in 5% to 20%. Three-line cells can be significantly abnormal morphology. 5. Refractory anemia with excess blasts type transformation (RAEB-T) patients are over the age of 50, but not uncommon in young adult domestic coverage. Liver and spleen not enlarged. RAEB blood and bone marrow in addition to a number of changes, often the following characteristics: the original peripheral blood c 5% but not more than 20%; primitive bone marrow cells in more than 20%, but less than 30%; primitive cells Auer bodies are visible; 50% of the patients evolved to acute leukemia, the patient survival time is short, most not more than one year. (C) WHO Classification (2000 Revision): In recent years, with cytology, immunology, genetics and molecular biology and its application in the rapid development of MDS diagnosis, classification, staging and prognostic applications, MDS classification system has been improved gradually, since 1995 WHO classification of MDS, an amendment made in 2000. The classification is as follows: MDS by the FAB classification criteria has been the transition to the WHO standard. Each department to determine whether abnormalities of other cells 0.10, the lowest so far no generally accepted morphological diagnostic criteria for MDS, there are difficulties in determining the diagnosis of RA patients should be regularly followed up. Etiology and pathogenesis of MDS, but the primary, that is, for unknown reasons. Or had chemical carcinogens, radiation therapy or history of exposure to alkylating agent, that is secondary. In all cases of acute leukemia, only a small number of clinical MDS can be clearly observed in the process. About 50% MDS patients with specific chromosomal abnormalities can be seen. Way MDS patients and whether the progress of transformation to acute leukemia, depends largely on the cell type is activated and the number of cancer genes. The disease is currently considered to occur at an early stage hematopoietic stem cells after damage to the result of clonal variation. Of bone marrow cells and chromosome banding analysis of G6PD isoenzymes, suggesting that MDS system evolved from a stem cell, so for cloning disease. Clinical manifestations of the disease onset and more insidious, more common in middle-aged male, about 70% of cases 50 years of age. Rare in children, but also increased incidence of young people in recent years. Diverse clinical manifestations, the lack of specific performance, often to anemia, bleeding and infection treatment, some patients may be asymptomatic, was found in the examination process. 1, anemia: In addition to individual patients, the vast majority of patients with varying degrees of symptoms as the main clinical manifestations of anemia, such as pale, dizziness, fatigue, shortness of breath, palpitations, etc. after the event. 2, bleeding: more than half of the patients had bleeding, but the early symptoms of mild bleeding, mostly for skin and mucous membrane bleeding, gum bleeding or epistaxis, because not serious and rarely require special treatment, women are rarely seen in patients with menorrhagia ; But with the development of the disease to the late, increased bleeding tendency, as in patients with cerebral hemorrhage leading cause of death. 3, the infection: neutropenia and function due to abnormal result in infection, early disease (refractory anemia, RA) more stable, more non-serious infections and fever, the late (RAEB or RAEBt) easier to co-infection. As low immunity, easy to cause potential abscess and septic arthritis, tuberculosis, Pseudomonas aeruginosa conjunctivitis, gangrene and other unusual infections. Fungal infection in the latter part of the more common, often septic complications and end-stage disease, the major cause of death. 4, the signs: some patients the liver, spleen, lymph nodes may have mild swelling, which can occur, but also occur alone was not significant because of the degree was easily ignored. Small number of patients may have tenderness of sternum, ribs or limbs, joint pain. MDS, the lack of specificity of symptoms onset, some patients may be no obvious symptoms. Most patients have dizziness, fatigue, abdominal discomfort and bone and joint pain. Most of onset of anemia, can be used as the first symptom of treatment, continuing for several months to several years. About 20% to 60% of the cases with bleeding tendency in the course of the disease, degree of severity varies, the performance of skin petechiae. Gum bleeding, epistaxis. Severe cases may have gastrointestinal or cerebral hemorrhage. Reduce bleeding and platelet related, some patients have defects in platelet function. About half of the patients in the course of the disease are fever, fever and infection, heat-type variable, respiratory infections, while the rest had sepsis, perianal, perineal infection. Without conversion to acute leukemia cases, infection and / or bleeding is the main cause of death. Liver, spleen, or may have mild swelling, 1 / 3 of the patients had enlarged lymph nodes, as painless. Individual patients with sternal tenderness. A laboratory examination, peripheral blood pancytopenia, the extent varies according to different classification. Such as refractory anemia (RA), anemia mainly refractory anemia associated with the original
Myelodysplastic syndrome therapy cells increased (RAEB), or changes in RAEB (RAEB-T) is often marked pancytopenia. Second, most patients bone marrow or bone marrow hyperplasia was extremely active, a small number of normal or reduced proliferation. MDS abnormal cell morphology reflects the pathological hematopoiesis. Immature erythroid cells in various stages of degeneration, often accompanied by class megaloblastic nuclear imbalance mature plasma, red blood cell volume large or oval, with basophilic stippling, nuclear fragmentation, and Howell-Jolly bodies. RA-S can be detected ring sideroblasts. Granulocyte in RAEB and RAEB-T were seen higher than normal proportion of primitive cells. Coarse grain granular cytoplasm or decrease in the nuclear sub leaves too much or too little, there Pelger-Hu


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