Bone marrow neoplastic

Bone marrow - neoplastic myeloid

Myelodysplastic syndromes (MDS)

MDS with excess blasts

Topic Completed: 1 August 2011

Minor changes: 6 December 2021

Copyright: 2002-2022,, Inc.

PubMed Search: MDS with excess blasts[TI]

Nikhil Sangle, M.D.
Page views in 2021: 2,192
Page views in 2022 to date: 84
Cite this page: Sangle N. MDS with excess blasts. website. Accessed January 21st, 2022.
Definition / general
  • Myeloblasts are 5 - 19% of bone marrow differential
  • Usually cytopenias in 2 or 3 lineages
  • Considered high risk MDS
  • Type 1: 5 - 9% blasts in bone marrow or 2 - 4% blasts in peripheral blood, no Auer rods, < 1 billion/L monocytes
  • Type 2: 10 - 19% blasts in bone marrow or 5 - 19% blasts in peripheral blood or Auer rods in any MDS (Am J Clin Pathol 2005;124:191), < 1 billion/L monocytes; more aggressive, greater tendency to progress to AML
  • Refractory anemia with excess blasts in transformation (RAEB-T): classified as AML under WHO classification
  • Median survival of 16 months for RAEB-1 and 9 months for RAEB-2 (Br J Haematol 2006;132:162)
  • Anemia (normochromic, normocytic or macrocytic), usually neutropenia and thrombocytopenia
Case reports
Microscopic (histologic) description
  • Peripheral blood: nucleated red blood cells, immature granulocytes, neutrophilic hyposegmentation, pseudo-Pelger-Huet cells and hypogranulation, myeloblasts 2 - 4% (RAEB-1) or 5 - 19% (RAEB-2), occasional micromegakaryocytes
  • Bone marrow: normocellular or hypercellular; hyperplasia of granulocytes or erythrocytes; myeloblasts comprise 5 - 9% (RAEB-1) or 10 -19% (RAEB-2) of white blood cells; Auer rods often seen; severe dysplastic changes in all 3 lineages, more severe than other MDS; abnormal localization of immature precursors (ALIP / clusters or aggregates of blasts located away from bone trabeculae and vascular structures); may have increased reticulin fibers
Microscopic (histologic) images

Peripheral blood:

Neutrophil has hypogranular cytoplasm

Neutrophil has hypogranular
cytoplasm and bilobed,

Bone marrow smear:

Blast in center with adjacent
hypogranular neutrophils,
erythroid precursor with multiple
nuclear fragments in upper left

and myelocytes
and 2 myeloblasts
on right

Large neutrophil (upper right) is hypogranular
with marked nuclear hyperlobulation, also single
myeloblast with prominent nucleolus and 2
neutrophils with markedly hypogranular cytoplasm


Auer rod present in blast, 6 - 8% myeloblasts, neutrophils show nuclear hypolobulation

RAEB-2: 47 year old woman with 12% myeloblasts and occasional Auer rods:

Normocellular biopsy

Normal erythroid precursors but shift to immature granulocytes

Same patient 4 years later has slightly more cellular marrow

High power shows
more immature granulocytes
than 4 years prior

RAEB-2: 62 year old man with pancytopenia and subsequent AML-M2:

Marked fibrosis with streaming effect
plus mature megakaryocytes,
some in clusters, no
shift to immaturity identified

Bone marrow aspirate
produced only a few cells,
including this blast with
an Auer rod

Images hosted on other servers:


Various images


Blood, marrow and myocardial infiltration

Molecular / cytogenetics description
Differential diagnosis
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