Introduction
The word leukemia literally means "white blood" and is used to describe a variety of cancers that begin in the blood-forming cells of the bone marrow.
White blood cells (leukocytes) evolve from immature cells referred to as blasts. Malignancy in these blasts is the source of leukemias, which generally progresses as follows:
- Normally, blasts constitute 5% or less of healthy bone marrow. In leukemia, however, these blasts remain abnormally immature and multiply continuously, eventually constituting between 30 - 100% of the bone marrow.
- Eventually these malignant blast cells fill up the bone marrow and prevent production of healthy red cells, platelets, and mature white cells (leukocytes).
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They spill out of the marrow into the bloodstream and lymph system and can travel to the brain and spinal cord (the central nervous system). As the number of normal cells decline, dangerous symptoms develop, which, if untreated, become lethal.
Leukemias are divided into two major types:
- Acute (which progresses quickly with many immature white cells)
- Chronic (which progresses more slowly and has more mature white cells)
Some blasts are called lymphoblasts (which become mature cells called lymphocytes) or myeloblasts (which mature to myeloid cells). Acute leukemias are in turn subdivided into two classifications according to whether the malignant blasts are lymphocytes or myeloid:
- Acute lymphocytic leukemia (ALL), which is the subject of this report
- Acute myeloid leukemia (AML)
Acute Lymphocytic Leukemia
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