Dysplastic changes of the red cell—Dyserythropoiesis
• Nuclear budding
• Ringed sideroblasts
• Internuclear bridging
• Megaloblastoid asynchrony
Dysplastic changes of the white cell—Dysgranu-lopoiesis
• Abnormal staining throughout the cytoplasm
• Nucleus with little segmentation
• Missing primary granules
• Granules that are poorly stained
Dysplastic changes of platelets—Dysthrombopoiesis
• Abnormal granules
• Giant platelets affected with multiple chromosomal abnormalities, showing marked erythroid hyperplasia with nuclear and cytoplasmic dysplastic changes. There are less than 1% blasts in peripheral blood.
Refractory anemia with excess blasts (RAEB) shows anemia, thrombocytopenia, and neutropenia.
Table 14.2 O The FAB and WHO Classifications of Myelodys-plastic Syndromes
The FAB Classification The WHO Classification
Refractory anemia Refractory anemia with ringed sideroblasts Refractory anemia with excess blasts Chronic myelomono-
cytic leukemia Refractory anemia with excess blasts in transformation
Refractory anemia Refractory anemia with ringed sideroblasts Refractory cytopenia with multilineage dysplasia
Refractory anemia with excess blasts
Myelodysplastic syndrome unclassifiable 5(q) chromosome abnormality
There are abnormalities in all myeloid cell lines with 5% to 19% blasts in the bone marrow. Two subclasses are recognized: RAEB 1, which shows 5% to 10% blasts in bone marrow, less than 5% blasts in the peripheral blood, and RAEB 2, which shows 10% to 19% blasts in the bone marrow and less than 20% blasts in the peripheral blood, hypercellular marrow in most cases.
Myelodysplastic syndrome unclassifiable is a condition that shares features of the MDSs but not a clearcut classification. Neutropenia and throm-bocytopenia are common.
Deleted 5q is seen in female patients primarily as a deletion of the long arm of chromosome 5. Normal or elevated platelet counts are seen. There is a marked anemia with macrocytes and less than 5% blasts in peripheral blood, associated with long survival times.
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