Demo page 6: PB and BM finding of MDS, WHO 2022 criteria
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Note: this is not a complete overview of all syndromes in the group of MDS, but only those that are important for the assessment of the morphology of blood and bone marrow.
Cytopenia is defined by:
Hemoglobin ♂ <13 g/dL (< 8,1 mmol/L) / ♀ <12 g/dL (< 7,4 mmol/L)
absolute neutrophil count < 1,8 x 10^9/L
platelet count < 150 x 10^9/L
The recommended thresholds for cytopenias established in the original International Prognostic Scoring System (IPSS) for risk stratification are:
haemoglobin concentration <10 g/dL
absolute neutrophil count < 1,8 x 10^9/L
platelet count < 100 x 10^9/L
The morphological classification is based upon number of blasts in peripheral blood and/or bone marrow, in combination with manifest morphologic dysplasia. At least 10% of a hematopoietic lineage shows dysplasia as threshold. However, the lineage(s) manifesting significant morphologic dysplasia frequently do not correlate with the specific cytopenia(s) in individual MDS cases.
Calculating blast percentage should be performed on all nucleated BM cells, not just the “nonerythroid cells.” (The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia):
MDS is grouped in two major sections: those with defining genetic abnormalities and those morphological defined.
If a leukocytosis (> 13 x 109/L), thrombocytosis (platelets ≥ 450 × 109/L, except in cases meeting criteria for MDS with del(5q) or with inv(3q)/t(3;3) cytogenetic aberrations), or monocytosis (monocytes ≥ 10% of leukocytes and absolute monocyte count ≥ 0.5 × 109/L) is present at the time of initial diagnosis this excludes MDS and classification as MDS/MPN or MPN should be considered.
Note: All MDS cases that are therapy related should be qualified as such by entering a “therapy-related” statement after the diagnosis.
Note: The presence of excess blasts supersedes any of the above MDS subtypes, except for MDS with mutated TP53
| diagnosis | cytopenias | dysplastic linaeges | peripheral blood blasts |
bone marrow blasts |
ring sideroblasts | cytogenetics | mutations |
| MDS with defining genetic abnormalaties | |||||||
| MDS with mutated TP53 | 1-3 | 0-3 | 0-9% | 0-9% | usually complex | Multi-hit TP53 mutation3 or TP53 mutation (VAF2> 10%) and complex karyotype often with loss of 17p | |
| MDS/AML with mutated TP53 | 1-3 | 0-3 | 10-19% | 10-19% | usually complex | Any somatic TP53 mutation (VAF2> 10%) | |
| MDS with del(5q) | ≥1 note: Thrombocytosis allowed |
≥1 | <2%1 | <5% | none or any | del(5q), with up to 1 additional, except −7/del(7q) |
Any, except multi-hit TP53 |
| MDS with mutated SF3B1 (MDS-SF3B1) | ≥1 | ≥0 | <2% | <5% | None or any Detection of ≥15% may substitute for SF3B1 mutation Alternative terminology: MDN with low blasts and ring sideroblasts |
Any, except isolated del(5q), −7/del(7q), abn3q26.2, or complex |
SF3B1 (≥ 10% VAF2), without multi-hit TP53 or RUNX1 |
| MDS, NOS without dysplasia | ≥1 | 0 | <2%1 | <5% | −7/del(7q) or complex | Any, except multi-hit TP53 or SF3B1 (≥ 10% VAF2) |
|
| MDS morphologically defined | |||||||
| MDS, NOS with single lineage dysplasia | ≥1 | 1 | <2%1 | <5% | not relevant | Any Except not meeting criteria for MDS-del(5q); The del(5q) must be isolated or accompanied by only one other cytogenetic aberration except for −7 or del(7q) |
Any, except multi-hit TP53 and not meeting criteria for MDS-SF3B1 |
| MDS, NOS with multilineage dysplasia | ≥1 | ≥2 | <2%1 | <5% | not relevant | Any Except not meeting criteria for MDS-del(5q); The del(5q) must be isolated or accompanied by only one other cytogenetic aberration except for −7 or del(7q) |
Any, except multi-hit TP53 and not meeting criteria for MDS-SF3B1 |
| MDS with excess blasts (MDS-EB) | ≥1 | ≥1 | 2-9%1 | 5-9% | Any | Any, except multi-hit TP53 |
|
| MDS/AML | ≥1 | ≥1 | 10-19% | 10-19% | Any, except AML-defining |
Any, except NPM1, bZIP CEBPA or TP53 |
1. 1% blasts confirmed twice on 2 separate occasions also qualifies for MDS-EB
2. Variant Allele Fraction
3. Defined as 2 distinct TP53 mutations (each VAF > 10%) OR a single TP53 mutation with (1) 17p deletion on cytogenetics; (2) VAF of >50%; or (3) Copy-neutral LOH at the 17p TP53 locus