1. Aplastic anemia is a condition characterized by pancytopenia (low red blood cells, white blood cells, and platelets) due to bone marrow failure. 2. It can be caused by exposure to toxins, radiation, viruses, or immune system attacks on the bone marrow. The bone marrow is hypocellular with fatty replacement of hematopoietic tissue. 3. Symptoms include anemia, increased risk of infection, bruising/bleeding due to low blood cell counts. Diagnosis involves blood tests showing pancytopenia and a bone marrow biopsy revealing a hypocellular marrow. Treatment options include supportive care, immunosuppressants, bone marrow transplant, or androgens