MDS with Excess Blasts

MDS with Excess Blasts

Myelodysplastic syndrome with excess blast is characterized by the presence of myeloblast in the peripheral blood (2-19%) and bone marrow (5-19%). It is further characterized base on the actual blast percentage into MDS-EB1 and EB2 which has prognostic significance.

Classification (WHO 2016)

MDS-EB1:  5 – 9% blasts in the bone marrow or 2-4% blasts in the peripheral blood, no Auer Rods in blast

MDS-EB2: 10 – 19% blasts in the bone marrow or 5 – 19% blasts in the peripheral blood 

Presence of Auer rods in blast classifies as MDS-EB2 irrespective of the blast percentage

Peripheral blood film of a patient with MDS-EB1. Note the occasional circulating myeloblast.

Blood Film Features:

• Cytopenias with dysplasia – usually quite florid (see MDS overview page for specific features)
• Myeloblast: count blast percentage for classification

Bone marrow aspirate of a patient with MDS-EB1.

Bone marrow aspirate of a patient with MDS-EB2.

Bone Marrow Features:

• Bone marrow usually hypercellular
• Dysplastic features (see MDS overview page for specific features)
• Myeloblast: count blast percentage for classification

Other Resources:

• ASH image bank:  Refractory Anemia with Excess Blasts
• Pathology Online: MDS with excess blasts