Myelodysplastic syndromes

Myelodysplastic syndromes

·        Description:

o  Heterogeneous group of disorders

o  Clonal abnormality of haemopoietic stem cells

o  Abnormal, ineffective haematopoiesis

o  Involves 1 or more lineages

o  Irreversible quantitative and qualitative defects (ie normal count but bad function)

o  Tendency to evolve to acute leukaemia

·        Clinical

o  Usually elderly 

o  Features of bone marrow failure: tired (anaemia), bleeding, infection, mild splenomegaly in 10 – 20%

o  Incidental finding on blood film in 20%

o  4 – 12 per 100,000 per year (definitional problems)

·        Variants:

o  Refractory anaemia +/- further features (eg excess blasts)

o  Chronic myelomonocytic leukaemia

·        Differential diagnosis:

o  Megaloblastic anaemia

o  Acute leukaemia

o  Heavy metal toxicity (lead, arsenic)

o  Chronic infection

o  Immune deficiency (esp HIV)

o  Anticancer chemo/radio therapy

o  Myeloproliferative disorders

o  Bone marrow hypoplasia

·        Progression:

o  70 – 80% die of marrow failure

o  20 – 30% die of progression to leukaemia

o  Median survival varies with subtype from 6 – 50 months

·        Treatment:

o  Response rates to treatment poor

o  Supportive care

o  Maybe cytotoxic chemotherapy or stem cell transplants in the few young cases

o  Growth factors eg erythropoietin

·        Secondary myelodysplasia: 

o  ­Incidence 

o  Complication of former treatment: alkylating agents (including cyclophosphamide, widely used as an immunosuppressive, eg in Rheumatoid arthritis) and topoisomerase II agents

o  Risk related to cumulative dose and duration of exposure

o  Peak 5 years post treatment

·        Poor prognosis