| disease | Myelodysplastic Syndrome |
Myelodysplastic syndrome (MDS) is a group of clonal disorders caused by differentiation disorders of hematopoietic stem cells. It is mainly characterized by a decrease in one or two lineages of peripheral blood cells, or pancytopenia, accompanied by cytomorphological abnormalities.
bubble_chart Diagnosis
1. Medical History and Symptoms
(1) History Inquiry: Pay attention to whether there was exposure to radiation, benzene and its derivatives, or chemotherapy drugs before the illness; whether there was a history of hematological diseases or non-hematopoietic tumors.
(2) Clinical Symptoms: Fatigue and lack of strength are common symptoms, and there may be palpitations, shortness of breath, epistaxis, and oral ulcers. A few patients are prone to recurrent infections.
2. Physical Examination Findings
Generally, an anemic appearance is observed, which may be accompanied by grade I splenomegaly. A few patients may develop rashes, while lymphadenopathy and bone tenderness are extremely rare.
3. Auxiliary Examinations
1. Blood Test: Pancytopenia or reduction in one or two cell lines. Abnormal manifestations such as macrocytes, nucleated red blood cells, and giant platelets may be observed.
2. Bone Marrow Examination: Most cases show hypercellularity or marked hypercellularity, with very few cases showing hypocellularity. Dysplasia is present in one, two, or all three of the erythroid, granulocytic, or megakaryocytic lineages.
3. Bone Marrow Biopsy: Abnormal distribution of blast cells, with clusters of blasts and promyelocytes between bone trabeculae.
4. Bone Marrow Histochemical Staining: Diffuse positivity for glycogen staining in nucleated red blood cells; clumped positivity for glycogen staining in dysplastic megakaryocytes.
Cytogenetic Examination: Ph1 chromosome negative; other chromosomal abnormalities may be observed.4. Classification and Differential Diagnosis
1. MDS Classification (See Table 4-1).
Table 4-1 MDS Classification
| Subtype | Blood Test | Bone Marrow Examination |
| Refractory Anemia (RA) | Blasts + Promyelocytes <1% | Blasts + Promyelocytes <5% |
| RA with Ringed Sideroblasts (RAS) | Same as above Ringed sideroblasts ≥15% | Same as above, with ringed sideroblasts in erythroid precursors |
| RA with Excess Blasts (RAEB) | Blasts + Promyelocytes <5% | Blasts + Promyelocytes account for 5–20% |
| RA with Excess Blasts in Transformation (RAEB-t) | Blasts + Promyelocytes >5% or presence of Auer rods | Blasts + Promyelocytes account for 20–30% or presence of Auer rods |
| Chronic Myelomonocytic Leukemia (CMML) | Any of the above subtypes with monocytes ≥1×109/L | Same as RAEB, with or without increased monocytic precursors |
2. Differential Diagnosis: The diagnosis of MDS should exclude acute myeloid leukemia, myelofibrosis, aplastic anemia, hemolytic anemia, megaloblastic anemia, and non-hematopoietic tumors.
bubble_chart Treatment Measures
Currently, there is no satisfactory treatment for MDS, and allogeneic bone marrow transplantation is the only curative method for MDS. The commonly used treatment methods include:
1. Supportive therapy: Red blood cell transfusion is recommended when hemoglobin levels fall below 60g/L; platelet transfusion is administered in cases of life-threatening bleeding due to thrombocytopenia; antibiotics should be used if infection occurs.
2. Treatment for RA and RAS: Managed similarly to chronic aplastic anemia. A minority of RAS cases respond to high-dose vitamin B6: 100–200mg, 2–3 times daily, administered orally. Maintenance therapy: 10–30mg/day.
3. Treatment for RAEB: Retinoic acid: 20mg, 3 times daily; or retinoic acid combined with low-dose cytarabine (10mg, every 12 hours, subcutaneously).4. Treatment for RAEB-t and CMML: Similar to RAEB. For patients under 50 years old with good general condition, chemotherapy regimens such as DA, HA, or intermediate-dose cytarabine may be used.
5. Application of cytokines: G-CSF, GM-CSF, or erythropoietin (Epo) 6,000–10,000 IU/day, administered subcutaneously. However, the use of G-CSF and GM-CSF remains controversial regarding whether it accelerates the transformation of MDS into leukemia. Therefore, these should not be used in patients with high blast cell counts.
