see also:

• haematology
• neutropenia

• aplastic anaemia is an auto-immune, rare (1-4 per million population) life threatening disorder in which the stem cells in bone marrow are destroyed leading to severe anaemia, thrombocytopenia and agranulocytosis (ie. pancytopenia)
• more frequent in teenagers and young adult but is also common among the elderly
• many have clones of cells (perhaps as an escape mechanism from immune destruction of stem cells) characteristic of paroxysmal nocturnal haemoglobinuria
• Rx is generally immunosuppressive drugs, blood transfusions and protection from infections whilst awaiting bone marrow transplant
  • for allografting (grafting between individuals), the donor's stem cells must be as compatible as possible with those of the recipient to avoid the risk of immunological complications including graft-versus-host disease

• ~50% of cases are idiopathic
• post-viral
  • 2% of cases of acute viral hepatitis
  • parvovirus may cause a short-lived aplastic anaemia as parvovirus binds to P antigen and causes temporary cessation of red cell production which is usually unnoticed as RBC life span is 120 days
  • EBV / glandular fever / infectious mononucleosis
  • cytomegalovirus (CMV)
  • HIV / AIDS
• vaccines
• medications
  • cytotoxic chemotherapy
  • chloramphenicol (> 1 in 40,000 Rx courses perhaps 1 in 100,000 risk?)
  • carbamazepine
  • felbamate
  • phenytoin
  • quinine
  • phenylbutazone
• chemicals
  • benzene
• radiation

• mild disease may self-resolve
• severe disease:
  • high risk of death if untreated
  • with stem cell transplant, 5 yr survival rates are¹⁾:
    • 42% for age < 20yrs
    • 32% for 20-40yrs
    • 10% for age > 40yrs
  • elderly not suited to stem cell transplants have a 5 yr survival up to 35% with immunosuppressive Rx
• 10–15% of severe aplastic anemia cases evolve into myelodysplastic syndrome and leukemia