4- APLASTIC ANEMIA

• Aplastic anemia


  Pancytopenia and hypocellularity of bone marrow, decreased number of pluripotent stem cells with fault or immune reaction in those remaining so that they're unable to repopulate the bone marrow
• Causes of aplastic anemia

  • Hereditary (e.g. Fanconi's anemia)
  • Idiopathic (67%)
  • Drugs (dose-related: chemotherapy, idiosyncratic: chloramphenicol, phenytoin, NSAIDs, carbamazepine)
  • Chemicals, benzene, insecticides, radiation
  • Infections (EBV, HIV, TB, hepatitis, parvovirus B19)
  • Paroxysmal nocturnal hemoglobinuria
  • SLE
  • B12 and folate deficiency
• Fanconi's anemia


  • DNA crosslink repair defect, associated with congenital malformations, AML, SCC, liver/brain/renal tumors, autosomal recessive, classic features include abnormal thumbs, absent radii, short stature, skin hyperpigmentation, chromosome fragility assay showing increased chromosomal breaks can make the diagnosis
• Signs and symptoms of anemia

  • Increased susceptibility to infection (mouth infections common)
  • Bleeding (bruising, bleeding gums, epistaxis)
• Pancytopenia


  Decreased or absent retics
• Bone marrow


  • Hypocellular with increased fat spaces (BM trephine biopsy is essential, dry aspiration)
• Prognosis factors


  • Neutrophils < 0.5x10^9
  • Platelets<20x10^9
  • Retics<40x10^9
• Definitive treatment


  1. Under 40 years: BMT from HLA identical donor

  2. Above 40 years: immunosuppressive treatment (antilymphocyte globulin & cyclosporine)
• The course of anemia is variable (spontaneous remission or persistent increasingly severe)
• Poor prognosis if neutrophils, platelets or retics are below certain thresholds