Aplastic anaemia

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Progressive bone marrow failure, resulting in pancytopenia. In some cases, there are identifiable factors such as drugs, chemicals, radiation and certain infections, but in a proportion of cases, no obvious cause is found.

The anaemia appears to be mediated by aberrant cytokine expression by T-cells, inhibiting haematopoiesis. Improvement with immunosuppressive treatments (usually ciclosporin and anti-thymocyte globulin) support an autoimmune cause, possibly following a trigger. Haematopoietic stem cell transplantation is second-line treatment.

Diagnosis

International Agranulocytosis and Aplastic Anaemia Study Group (1987):

  • At least 2 lineages affected in peripheral blood:
    • Haemoglobin <10g
    • Neutrophils <1.5
    • Platelets <50
  • Bone marrow:
    • Cellularity <30% (not applicable to older individuals)
    • Absence of dysplasia or bone marrow fibrosis.

Other diagnoses to consider/exclude:

Severity

Graded according to modified Camitta criteria.[2][3] Of less prognostic value now with more effective treatments.

Non-severe AA
Decreased bone marrow cellularity and peripheral blood cytopenia, not fulfilling criteria for SAA
Severe AA
Bone marrow cellularity <25%. 2 or more of following: neutrophil count <0.5 × 109/l, platelet count <20 × 109/l, reticulocyte count <20 × 109/l.
Very severe AA
Criteria of severe AA and neutrophil count <0.2 × 109/l

References