Overview
Myelodysplasia refers to the presence of morphologically and functionally abnormal blood cells.
Myelodysplasia may be seen in the context of myelodysplastic syndromes (MDS), where clonal expansion of mutated stem cells results in ineffective haematopoiesis. This condition is at risk of transforming to acute myeloid leukaemia (AML).
Myelodysplasia may also occur due to secondary causes which may be reversible.
Pathogenesis
Causes of Myelodysplasia
Primary
- Myelodysplastic syndromes (MDS)
- Myelodysplastic / myeloproliferative neoplasms - chronic myelomonocytic leukaemia (CMML)
Secondary
- Cytotoxic chemotherapy
- Benzene exposure
- Ionising radiation
Diagnosis
Investigations
- Blood film - evidence of dysplasia
- Bone marrow aspirate + trephine - histology, cytogenetics, molecular, flow cytometry
Blood Film Findings in Myelodysplasia
Red Blood Cells
- Macrocytic hyperchromic anaemia
- Anisocytosis: variation in the size of red blood cells
- Poikilocytosis (abnormal red cell shape)
- Basophilic stippling
- Nucleated red blood cells
White Blood Cells
- Leukocytosis or leukopaenia
- Hypogranular neutrophils
- Pseudo Pelger-Huet neutrophils: hypolobated neutrophils with peanut-shaped or spectacle-shaped nuclei
Platelets
- Thrombocytopaenia
- Platelet anisocytosis: variation in size of platelets, with large and sometimes giant platelets seen
Other
- Circulating blasts may be seen
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