Leukemia
Life-threatening disorderDescription
Abnormal, uncontrolled proliferation of white blood cells (WBCs)
Acute lymphocytic leukemia (ALL) most common type of leukemia and cancer in children
Peak age 2 to 5
90% to 95% of children achieving a first remission
Almost 80% living 5 years
Child between ages 3 and 7 and an initial WBC count of less than 10,000/µl at the time of diagnosis having the best prognosis
Acute myeloblastic (myelogenous) leukemia (AML) more common than ALL in adolescents
50% to 70% of adolescents achieving a first remission
40% living 5 years
Pathophysiology
WBCs produce so rapidly that immature cells (blast cells) release into the circulation.
Blast cells are nonfunctional, can’t fight infection, and multiply continuously without respect to the body’s
needs; they appear in the peripheral blood (where they normally don’t appear).
Blast cells are as high as 95% in the bone marrow (normally less than 5%), as measured by marrow aspiration in the posterior iliac crest (the sternum can’t be used in children).
Increased proliferation of WBCs robs healthy cells of nutrition.
Bone marrow first undergoes hypertrophy, possibly resulting in pathologic fractures.
Bone marrow then undergoes atrophy, which results in a decrease in all blood cells, leading to anemia, bleeding disorders, and immunosuppression.
Causes
Exact cause unknown
Increasing evidence suggesting a combination of contributing factors
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