eTable 1. WHO classification of myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasias (11, 12).
| MDS subtype | Blood | Bone marrow |
|---|---|---|
| Refractory cytopenia with unilineage dysplasia (RCUD) Refractory anemia (RA) Refractory neutropenia (RN) Refractory thrombocytopenia (RT) |
<1% blasts Uni- or bicytopenia |
<5% blasts Dysplasia in ≥10% of cells of only one lineage |
| Refractory anemia with ring sideroblasts (RARS) | Anemia, no blasts | <5% blasts, ≥ 15% ring sideroblasts within erythropoiesis, exclusively dyserythropoiesis |
| Refractory cytopenia with multilineage dysplasia (RCMD) with or without ring sideroblasts | <1% blasts Cytopenia <1000/μl monocytes |
<5% blasts, signs of dysplasia in ≥10% of cells of 2 to 3 lineages |
| MDS with isolated del(5q) | <1% blasts Anemia, platelets often increased |
Mostly typical mononuclear megakaryocytes, <5% blasts, isolated del(5q) abnormality |
| Refractory anemia with excess of blasts I (RAEB I) | Cytopenia <5% blasts <1000/μl monocytes |
Uni- or multilineage dysplasia, blasts 5% to 9%, no Auer rods |
| Refractory anemia with excess of blasts II (RAEB II) | Cytopenia <20% blasts <1000/μl monocytes Auer rods may be found |
Uni- or multilineage dysplasia, blasts 10% to 19%, Auer rods may be found |
| Unclassified MDS (MDS-U) RCUD with pancytopenia RCMD/RCUD with 1% blasts in blood MDS-typical chromosomal aberration without clear signs of dysplasia |
<1% blasts <1000/μl monocytes |
<5% blasts |
| Myelodysplastic/myeloproliferative neoplasias | ||
| Chronic myelomonocytic leukemia I (CMML I) | <5% blasts Uni- or bicytopenia 1000/μL monocytes No Auer rods |
<10% blasts, dysplasia in >10% of cells of 1 to 3 lineages, no Auer rods |
| Chronic myelomonocytic leukemia II (CMML II) | <20% blasts Uni- oder bicytopenia 1000/µL monocytes Auer rods may be found |
<20% blasts, dysplasia in >10% of cells of 1 to 3 lineages, Auer rods may be found |
| Refractory anemia with ring sideroblasts and thrombocytosis (RARS-T) | Cytopenia 450000/μL platelets <1% blasts |
<5% blasts, >15% ring sideroblasts within erythropoiesis, dysplasia in >10% of cells of 1 to 3 lineages, no Auer rods, often sf3b1 and jak-2 mutations |
WHO, World Health Organization; MDS, myelodysplastic syndromes