Overview of Myelodysplastic/Myeloproliferative Neoplasms

Overview of Myelodysplastic/Myeloproliferative Neoplasms

Kathryn Foucar, MD

Blood smear from a patient with MDS/MPN shows marked leukocytosis with left shift. The patient also has a moderate anemia, while the platelet count is preserved. Note dysplastic neutrophils image.

Marked dysplastic features of neutrophils are evident in this peripheral blood smear from a patient with MDS/MPN. Note the nuclear segmentation abnormalities and hypogranularity of the neutrophil image.



  • Myelodysplastic/myeloproliferative neoplasms (MDS/MPN)


  • De novo clonal chronic myeloid neoplasm characterized by hybrid myelodysplastic and myeloproliferative features manifested by at least 1 cytopenia and at least 1 cytosis in blood

  • Maturation is intact, mature cells predominate

  • Blasts and blast equivalents are < 20% in blood and bone marrow

  • Multiple subtypes defined with specific criteria

WHO 2008 Classification of MDS/MPN

  • Chronic myelomonocytic leukemia (CMML)

  • Atypical chronic myeloid leukemia, BCR-ABL1 negative (aCML)

  • Juvenile myelomonocytic leukemia (JMML)

  • Myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN-U)

  • Refractory anemia with ring sideroblasts and thrombocytosis (RARS-T) (provisional category)


Molecular Genetic Findings

  • No disease defining molecular/cytogenetic features

  • Aberrations in RAS/MAPK signaling pathways common and linked to abnormal cell proliferation

    • May include mutations in PTNPN11, NRAS, KRAS, or NF1 most notably in JMML

  • Many exclusionary genetic findings including absence of BCR-ABL1, PDGFRA/B, FGFR1 mutations, isolated del(5q), inv3(q21q26), and AML-defining translocations

    • All of these mutations are pathogenetically linked to other types of myeloid neoplasms

Jun 13, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Overview of Myelodysplastic/Myeloproliferative Neoplasms
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