| Morphological Subtype | Peripheral Blood | Bone Marrow |
|---|---|---|
| Refractory Anemia (RA)* (12-43%of cases) | Blasts <1% | Blasts <5% Erythroid hyperplasia Dyserythropoiesis No or few ringed sideroblasts |
| Refractory Anemia with Ring Sideroblasts (RARS) (14-37% of cases) | Blasts <1% Occasional dysplastic neutrophils and platelets |
Blasts <5%; >15% of NRBC are ring sideroblasts Erythroid hyperplasia |
| Refractory Anemia with Excess Blasts (RAEB) (13-43% of cases) | Blasts <5% Cytopenias |
Blasts 5-19% Panmyeloid hyperplasia >15% ringed sideroblasts |
| Refractory Anemia with Excess Blasts in Transformation (RAEB-T) (4-27% of cases) | Blasts >5% or Auer rods present** Cytopenia |
Panmyeloid hyperplasia Blasts 20-29% or Auer rods present** |
| Chronic Myelomonocytic Leukemia (CMML) (1-22% of cases) | As any of the above but with >1 x 109/l monocytes 5 – 29% blasts |
As any of the above with or without an increase in monocytes and/or promonocytes |
| Myelodysplastic syndrome unclassified (MDS-U) | < 5% blasts Cytopenias < 1% blasts |
< 5% blasts Multilineage dysplasia |