Aplastic Anemia

• Pancytopenia caused by bone marrow insufficiency

• Should NOT be confused with aplastic crisis, a condition in which erythropoiesis is temporarily suppressed (e.g., due to parvovirus B19 infection in patients with hemolytic anemias)

• Idiopathic in > 50% of cases

  • Possibly immune-mediated

  • May follow acute hepatitis (hepatitis-associated aplastic anemia)

• Medication side effects: carbamazepine, methimazole, NSAIDs, chloramphenicol, propylthiouracil, sulfa drugs, cytostatic drugs (esp. alkylating agents and antimetabolites)

• Toxins: benzene, cleaning solvents, insecticides, toluene

• Ionizing radiation

• Viruses: HBV, EBV, CMV, HIV

• Fanconi anemia

• Hereditary autosomal recessive disorder due to a DNA crosslink repair defect resulting in bone marrow failure

• Skeletal and organ abnormalities: short stature, hypo- and hyperpigmentation, cafe-au-lait spots, microcephaly, developmental delay, thumb and forearm malformations, kidney, GI, heart, eye, and ear abnormalities

• Laboratory tests show pancytopenia and normocytic or macrocytic anemia.

• ∼ 50% of patients with Fanconi anemia will develop acute myeloid leukemia or myelodysplastic syndromes in early adulthood.

• Fatigue, malaise

• Pallor

• Purpura, petechiae, mucosal bleeding

• Infection

• CBC:

  • Pancytopenia (in contrast to aplastic crisis characterized by anemia only)

  • Normocytic or macrocytic anemia

• Reticulocyte count: low

• EPO level: high

• Bone marrow biopsy findings

  • Hypocellular fat-filled marrow (dry bone marrow tap)

  • RBCs normal morphology

• Cessation of the causative agent

• Supportive therapy

  • Treatment of infections

  • Blood transfusion

  • Platelet transfusion

• Bone marrow stimulants (e.g., GM-CSF, eltrombopag)

• Immunosuppressive therapy

  • Cyclosporine

  • Antithymocyte globulin (ATG)

  • Tacrolimus

  • Alemtuzumab

• Consider hematopoietic cell transplantation (HCT) in young patients.

Can't Make New Blood Cells Properly = Carbamazepine, Methimazole, NSAIDs, Benzenes, Chloramphenicol, Propylthiouracil

Aplastic anemia

Photomicrograph of a bone marrow biopsy (H&E stain; 100x magnification)

The marrow is hypocellular and fat-filled.

This is the characteristic histological appearance of aplastic anemia.