Table 1.

2016 WHO Criteria of classifications of myelodysplastic syndromes

Type	Dysplastic lineages	Cytopenias1	Ring sideroblasts in erythroid elements of BM	Blasts	Cytogenetics
MDS-SLD	1	1 or 2	RS<15% (or <5%2)	PB <1% BM <5% No Auer rods	Any, unless fulfills criteria for isolated del(5q)
MDS-MLD	2 or 3	1-3	RS<15% (or<5%2)	PB <1% BM <5% No Auer rods	Any, unless fulfills criteria for isolated del(5q)
MDS-RS
MDS-RS-SLD	1	1 or 2	RS≧ 15% (or ≧5%2)	PB <1% BM <5% No Auer rods	Any, unless fulfills criteria for isolated del(5q)
MDS-RS-MLD
	2 or 3	1-3	RS≧ 15% (or ≧5%2)	PB <1% BM <5% No Auer rods	Any, unless fulfills criteria for isolated del(5q)
MDS with isolated del(5q)	1-3	1-2	None or any	PB <1% BM <5% No Auer rods	del(5q) alone or with 1 additional abnormality except -7 or del(7q)
MDS-EB
MDS-EB-1	0-3	1-3	None or any	PB 2 ~ 4% or BM 5 ~ 9%, no Auer rods	Any
MDS-EB-2	0-3	1-3	None or any	PB 5 ~ 19% or BM 10% ~ 19% or Auer	Any
MDS-U With 1% PB blast	1-3	1-3	None or any	PB = 1%3, BM < 5%, Auer rods	Any
with SLD and pancytopenia	1	3	None or any	PB <1% BM <5% No Auer rods	Any
Defining cytogenetic abnormality	0	1-3	<15%4	PB <1% BM <5% No Auer rods	MDS defining abnormality
RCC	1-3	1-3	None	PB < 2% BM < 5% No Auer rods	Any

WHO: World Health Organization; MDS: myelodysplastic syndromes; PB: peripheral blood; BM: bone marrow; RS: ring sideroblasts;

MDS-SLD: MDS with single lineage dysplasia; MDS-MLD: MDS with multilineage dysplasia; MDS-EB: MDS with excess blasts;

MDS-U: MSD, unclassifiable; RCC: refractory cytopenia of childhood.

¹Cytopenias MDS-defining: Hb < 100g/L, PLT < 100 × 10⁹/L, ANC < 1.8 × 10⁹/L; absolute monocytes count < 1.0 × 10⁹/L;

²with SF3B1 mutation;

³1% PB blasts must be recorded on at least two separate observations;

⁴If with >15% ring sideroblasts and significant erythroid dysplasia, and are classified as MDS-RS-SLD.