Aplastic Anemia

INTRODUCTION:
  • Pancytopenia resulting from aplasia of the B.M.
  • classified into primary and secondary types.
  • The bone marrow produces too few of all three types of blood cells: red cells, white cells, and platelets (pancytopenia) 
ETIOLOGY:
  • Primary:
  1. congenital (as Fanconi's anemia).
  2. Idiopathic acquired (67% of cases).
  • B- secondary:
  1. Chemicals (benzene, toluene, glue sniffing).
  2. Drugs (chemotherapeutics, antibiotics, gold,Carbamazepine , phenytoin)
  3. Insecticides.
  4. Ionizing radiation
  5. Infections (as hepatitis).
  6. Parvovirus
  7. HIV-1
  8. Pregnancy
  9. Chloramphenicol
  10. Paraxysmal nocturnal haemoglobinuria.
PATHOGENESIS:
  • Reduction in the number of haemopoietic pluripotential stem cells: fault in the remaining stem cells
  • Immune reaction against stem cell : unable to divide and differentiate sufficiently to produce the blood cells.
CLINICAL FEATURES:
  • Anemia with malaise, pallor and other associated symptoms such as palpitations.
  • Fever ,Weakness
  • Thrombocytopenia (low platelet counts), leading to increased risk of hemorrhage, bruising and petechiae.
  • Leukopenia (low white blood cell count), leading to increased risk of infection.
  • Reticulocytopenia (low reticulocyte counts).
  • Occurs at any age.
  • Male predominance.
DIAGNOSIS:
  • Complete Blood Picture (CBP): which shows pancytopenia and reticulocytes.
  • Bone marrow aspirate: Markedly hypocellular marrow, due to replacement of hemopoietic marrow by adipose tissue (not fibrosis or neoplastic cells).
THERAPY:
  • General:
  1. The cause is removed.
  2. Supportive care with blood Transfusion, paltlets concentrate.
  3. Prevention of infection.
  • Specific:
BONE MARROW TRANSPLANTATION:
  1. Treatment of choice.
  2. From HLA matched donor. Usually siblings.
  3. Long term survival rates: 60-70%.
  • IMMUNOSUPPRESSION: by using drugs
  1. Antithymocyte globulin (ATG)
  2. Antilymphocyte glubulin (ALG)
  3. Cyclosporin
  4. Intensive immunosupression : cyclophosphami
  5. Corticosteroids.
  • Splenectomy 
Exam Question
  • A patient aged 65 years, is diagnosed to have severe aplastic anemia with HLA compatible sibling is best treated with Antithymocyte globulin followed by cyclosporine
  • Carbamazepine may lead to aplastic anemia.
  • Parvovirus causes aplastic anemia in chronic hemolytic diseases
  • Pancytopenia is caused by Aplastic anemia
  • Reticulocytopenia is caused by Aplastic anemia 
  • Aplastic anemia can progress to AML,Myelodysplastic anemia,Paroxysmal nocturnal hemoglobinuria
  • Splenectomy done in Aplastic anemia
  • Aplastic anemia is seen in PNH,Chloramphenicol,HIV- I,Pregnancy,Gold salts
  • Fever , weakness,splenomegaly , low hemoglobin & pancytopenia are features seen in aplastic anemia
  • Most common cause of aplastic anemia is Exposure to drugs
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