A disorder where the bone marrow fails to produce enough new blood cells.
* Progressive weakness * Fatigue * Lethargy * Headache after exertion * Respiratory problems after exertion * Increased susceptibility to bacterial infection * Low blood cell count * Anemia * Pale skin * Waxy skin * Brown skin pigmentation * Low blood platelet level * Bleeding into skin * Bleeding into mucous membranes * Hemorrhagic skin spots * Mucosal ulceration * Tachycardia * Systolic murmur
Aplastic anemias usually develop when damaged or destroyed stem cells inhibit red blood cell (RBC) production. Less commonly, they develop when damaged bone marrow microvasculature creates an unfavorable environment for cell growth and maturation. About one-half of such anemias result from drugs (antibiotics and anticonvulsants), toxic agents (such as benzene and chloramphenicol), or radiation. The rest may result from immunologic factors (unconfirmed), severe disease (especially hepatitis), or preleukemic and neoplastic infiltration of bone marrow. Idiopathic anemias may be congenital. Two such forms of aplastic anemia have been identified: Congenital hypoplastic anemia (Blackfan-Diamond anemia) develops between ages 2 and 3 months; Fanconi’s syndrome, between birth and age 10. In Fanconi’s syndrome, chromosomal abnormalities are usually associated with multiple congenital anomalies, such as dwarfism, and hypoplasia of the kidneys and spleen. In the absence of a consistent familial or genetic history of aplastic anemia, researchers suspect that these congenital abnormalities result from an induced change in the fetus’development. Incidence is 0.6 to 6.1 cases per 1 million people. There is no racial predilection.
Identifiable causes must be eliminated and vigorous supportive measures must be provided, such as transfusions of packed RBCs and platelets. Human leukocyte antigen–matched leukocytes or antithymocyte globulin, used alone or in combination with cyclosporine, has especially impaired outcomes for children and severely neutropenic patients. Experimental trials of androgen therapy are in process. Even after elimination of the cause, recovery can take months. Bone marrow transplantation is the treatment of choice for patients with anemia resulting from severe aplasia and for patients who need constant RBC transfusions.