1. Bone Marrow Aplasia Objective 3: Discuss the components and causes of bone marrow aplasia.

2. Morphology/Components ( Modern Hematology Biology and Clinical Management, Second Edition © 2007 Humana Press Inc.; Robbins 8 th Ed.): Contains acellular or hypocellular “spicules” (spicules: small needle-shaped bodies). Cellular elements: –May include a minimal number of residual myeloid or erythroid cells. –Plasma cells and lymphocytes may be relatively increased in numbers but they do not represent clonal populations. –Fat cells and fibrous stroma

3. Severe damage to the hematopoietic cell compartment --> replacement of bone marrow by fat Committed and primitive progenitor cells are virtually absent Idiopathic Acquired Hereditary

4. Idiopathic About 60% of cases

5. Acquired Drugs (anti-cancer agents, antibiotics, anti- inflammatory agents, seizure medications, and antithyroid drugs) Radiation: marrow aplasia is a major sequela of radiation Chemical exposure (benzene and insecticides)

6. Acquired Infection –Hepatitis: most common preceding infection; seronegative –Epstein Barr Virus, Parvovirus, HIV Pregnancy: rare; resolves with delivery or abortion Paroxysmal nocturnal hemoglobinuria, graft-vs-host disease, connective tissue diseases

7. Hereditary Relatively rare Fanconi's anemia –Progressive pancytopenia –Short stature, café au lait spots, anomalies of thumb and radius and GUT Shwachman-Diamond syndrome Dyskeratosis congenita –Aplastic anemia during childhood –Mucous membrane leukoplasia –Dystrophic nails