refractory anemia with excess blasts
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Clinical- age 50+
- 40% of MDS
- anemia, thrombocytopenia, neutropenia
- progress to AML (25% RAEB1, 33% RAEB2)
- CD7 = poorer prognosis
- prognosis: RAEB1 > RAEB2 by Auer rod > RAEB2 by blast count
Types- RAEB1: 5-9% marrow blasts or 2-4% blood blasts
- RAEB2: 10-19% marrow blasts, 5-19% blood blasts, or Auer rods in blast
- RAEBF: myelofibrosis
Morphology—- anisopoik—- giant plt, hypogranular plt- neutrophils: abnormal granularity, segmentation
- 2-19% blasts
- marrow
- usually hypercellular, abnormal paratrabecular clustering of erythroids and megas
- erythroid
- can be increased
- macrocytic
- megaloblastoid
- abnormal lobation, nuclear bridging
- granulocytic
- usually increased
- small neuts
- nuclear hypolobation, hypersegmentation
- cytoplasmic hypogranularity, pseudo Chediak Higashi granules
- megakaryocyte
- normal to increased
- paratrabecular clustering
- micromegakaryocytes
- multinucleation
- 5-19% blasts, tend to localize away from trabeculae and vessels
Immunophenotype- precursor cells (CD34, CD117)
- myeloid lineage: CD13, CD33
- can have aberrant CD7 (worse prognosis), CD56
- CD61 stains dysplasic megas
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