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Lawrence B. Gardner

and Chi V. Dang

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date: 28 April 2017

Myelodysplasia is a common haematological disorder that may occur at any age, although prevalence increases with age and most patients are over 60 years old. It is associated with a wide variety of acquired clonal abnormalities that may affect all lineages of blood cells and frequently lead to the development of leukaemia. Some particular chromosomal abnormalities are characteristic, and in a few cases functional studies of candidate genes implicated in the chromosomal abnormalities suggest cause–effect relationships, e.g. an activating mutation in the JAK2 kinase.

Clinical features, diagnosis, and classification

Most patients present with features of chronic anaemia or manifestations related to thrombocytopenia (bleeding and bruising) or infection (usually when the absolute neutrophil count is <0.5 × 109/litre).

Diagnosis—this may be suggested by the presence of normocytic or macrocytic anaemia, with the peripheral blood smear showing dysplastic changes in red blood cells and/or neutrophils. Bone marrow aspirate and biopsy confirms these findings and permits detailed cytogenetic study, which is critical for diagnostic classification and prognosis

Classification—based on the morphological appearance of the peripheral blood and bone marrow, the following are recognized in the World Health Organization (WHO) classification: (1) refractory anaemia; (2) refractory anaemia with ringed sideroblasts; (3) refractory cytopenias with multilineage dysplasia; (4) refractory cytopenias with multilineage dysplasia and ringed sideroblasts; (5) refractory anemia with excess blasts-1; (6) refractory anemia with excess blasts-2; (7) 5q– syndrome; and (8) other subtypes—including chronic myelomonocytic leukaemia, refractory anaemia with thrombocytosis, and secondary myelodysplastic syndrome.

Treatment and prognosis

Treatment is symptomatic in most cases. The only potentially curative treatment is allogeneic bone marrow transplantation, but this is not usually an option for the elderly. Some patients, particularly those with a hypocellular marrow, may show a response to immunosuppression with ciclosporin. Many of the few patients with isolated 5q– deletions respond dramatically to lenalidomide, an immunomodulatory and antiangiogenic drug.

Prognosis—mean survival is 12 to 28 months from the time of diagnosis, but prognosis varies widely according to particular subtype. Most patients die as a result of either bleeding or infection, but in some transformation to leukaemia proves fatal.

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