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Myelodysplastic syndromes
Other Resources UpToDate PubMed

Myelodysplastic syndromes

Contributors: Nina Haghi MD, Paritosh Prasad MD
Other Resources UpToDate PubMed


Myelodysplastic syndrome (MDS) is a rare clonal hematopoietic stem cell disorder characterized by abnormal (dysplastic) blood cells, ineffective bone marrow function, and decreased blood cell counts (cytopenias). There are various types of MDS, classified based on peripheral blood, bone marrow, and cytogenetic features. The risk of developing MDS increases with age, and the median age at diagnosis is 65 years or older, with a male predominance. Some types of MDS are related to prior chemotherapy.

The peripheral blood smear usually demonstrates low cell counts (ie, anemia, thrombocytopenia, leukocytopenia) and dysplastic features in RBCs (basophilic stippling, megaloblastic changes, etc) and/or WBCs (hyposegmented or hypersegmented granulocytes, hypogranularity, etc).

The bone marrow aspirate and biopsy will usually show hypercellularity, as well as single- or multi-lineage dysplasia. Maturing RBCs may show nuclear budding, irregularity, or bridging. Ring sideroblasts may be seen. Megakaryocytes may show hypolobulation of the nucleus. Myeloblasts may be present; however, they must comprise less than 20% of cells. Certain cytogenetic abnormalities may also be present that can determine the subtype of MDS.

Depending on MDS subtype, patients may be at higher risk of developing acute myeloid leukemia (AML).


D46.9 – Myelodysplastic syndrome, unspecified

109995007 – Myelodysplastic syndrome

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Poor nutritional status can lead to dysplastic features of blood cells. Causes include Copper deficiency, zinc excess, Vitamin B12 deficiency, Folate deficiency, and Alcohol use disorder.
  • Certain medications can mimic MDS findings.
  • Inherited disorders such as sideroblastic anemia may present with similar abnormalities.
  • Human immunodeficiency virus disease
  • Aplastic anemia
  • Acute myeloid leukemia
  • Chronic myeloid leukemia (CML)
  • Myelofibrosis
  • VEXAS syndrome

Best Tests

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Management Pearls

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Reviewed:01/18/2018
Last Updated:07/26/2021
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Myelodysplastic syndromes
A medical illustration showing key findings of Myelodysplastic syndromes : Fatigue, Fever, Pancytopenia, Dyspnea, Pallor, Splenomegaly, WBC decreased, PLT decreased, RBC decreased
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