Chronic Myeloid Neoplasms
Myelodysplastic syndromes
MDS - WHO classification

Author: Nikhil Sangle, M.D. (see Authors page)

Revised: 1 March 2017, last major update August 2011

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PubMed Search: MDS WHO classification

Cite this page: MDS - WHO classification. PathologyOutlines.com website. http://pathologyoutlines.com/topic/myeloproliferativemdsclasswho.html. Accessed May 29th, 2017.
WHO 2008 Classification
  • Refractory anemia (RA): < 5% blasts, > 15% ringed sideroblasts; variable marrow cellularity, unicytopenia or bicytopenia, unilineage dysplasia > 10% in one myeloid lineage
  • RA with Ringed Sideroblasts (RARS): 15% or more sideroblasts, less than 5% blasts, erythroid dysplasia only
  • Refractory cytopenia with multilineage dysplasia (RCMD): cytopenia, < 5% blasts, dysplasia in > 10% of cells in two or more lineages, no Auer rods
  • RA with Excess Blasts (RAEB): type 1 has 5 - 9% blasts in blood / marrow, peripheral cytopenia, unilineage or multilineage dysplasia, no Auer rods; type 2 has 10 - 19% blasts in blood / marrow, unilineage or multilineage dysplasia, Auer rods may be present, peripheral cytopenia
  • MDS with isolated 5q- syndrome: anemia, < 5% blasts, del(5q), no Auer rods, normal / increased hypolobated megakarycoytes
  • MDS, unclassified: cytopenia(s), dysplasia in < 10% of cells in one or more myeloid cell lines, accompanied by cytogenetic abnormalities with presumptive evidence of MDS, < 5% blasts
  • Therapy related MDS
Changes of WHO 2001 from FAB
French American British (FAB) Classification System for Myelodysplasia (used prior to WHO)
  • Refractory anemia (RA): < 5% blasts, < 15% ringed sideroblasts; variable marrow cellularity
  • RA with Ringed Sideroblasts (RARS): 15% or more sideroblasts, less than 30% erythroblasts
  • RA with Excess Blasts (RAEB): 5 - 30% blasts in marrow, < 5% in peripheral blood
  • RA with Excess Blasts in Transformation (RAEB-T): 20 - 30% blasts in marrow, > 5% in peripheral blood (now AML in WHO classification)
  • Chronic myelomonocytic leukemia (CMML): elevated WBC, monocytosis > 1 billion/liter; trilinear dysplasia; 5 - 20% blasts in marrow, > 5% in peripheral blood
  • MDS, unclassified