chronic leukemia is usually gradual because these
cells, though defective, can function to some
extent and enter the blood circulation at the nor-
mal rate. In all types of leukemia, the defective
cells also block the bone marrow from producing
platelets and erythrocytes, resulting in dysfunc-
tional COAGULATION(clotting) and ANEMIA.
Acute lymphatic leukemia (ALL) The most
common leukemia of childhood, ALL arises when
a genetically damaged lymphoid clone cell in the
bone marrow proliferates, causing immature lym-
phocytes, called lymphoblasts or leukemic blasts,
to replace healthy lymphocytes in the bone mar-
row and the blood circulation. The accumulation
prevents normal HEMATOPOIESIS, resulting in ane-
mia, coagulation dysfunction, and vulnerability to
INFECTION. About 85 percent of ALL involves B-cell
lymphocytes and the remaining 15 percent
involves T-cell lymphocytes. Doctors diagnose
about 4,000 people a year with ALL in the United
States.
Chronic lymphatic leukemia (CLL) Doctors
diagnose about 8,000 people a year with CLL in
the United States, more than 75 percent of them
being over the age of 60. In CLL, the proliferating
defective lymphocytes function normally. CLL
may generate no symptoms or ill effects, in which
case doctors generally opt for watchful waiting as
the treatment approach. As CLL progresses, how-
ever, it causes dysfunctional IMMUNE RESPONSE.
Defective lymphocytes that accumulate in the
bone marrow eventually suppress bone marrow
function.
Acute myeloid leukemia (AML) The most com-
mon leukemia among people over age 40, AML
arises through the proliferation of a defective
myeloid clone cell and manifests in one of seven
forms. Doctors designate these forms as subtypes
M1 through M7, according to the cells involved.
The subtype determines the course of treatment
and likelihood for REMISSION. As with ALL, the pro-
liferation of the defective clone prevents normal
hematopoiesis with consequent THROMBOCYTOPENIA,
anemia, and often NEUTROPENIA. Doctors diagnose
about 12,000 people a year with AML in the
United States.
Chronic myeloid leukemia (CML) Nearly
always a cancer occurring in adulthood, CML
results from the translocation of chromosomes 9
and 22, an acquired MUTATIONcommonly referred
to as the Philadelphia, or Ph, CHROMOSOME.
Researchers do not know what causes the abnor-
mality, which produces the rampant proliferation
of monocytes or granulocytes that function nor-
mally. Other hematopoiesis is normal as well.
Doctors diagnose about 54,000 people a year with
CML in the United States.Symptoms and Diagnostic Path
Symptoms of leukemia develop when the cancer-
ous cells in the blood circulation begin to outnum-
ber the healthy cells. Early symptoms are insidious
and often mimic those of common viral infections.
As the leukemia progresses, symptoms become
more pronounced and typically include- unexplained low-grade FEVER
- general malaise or lethargy
- PAINin the joints
- unintended weight loss
- sweating at night
- loss of APPETITE
- tiredness or fatigue
- easy bleeding or bruising, or the appearance of
PETECHIAE(pinpoint hemorrhages beneath the
SKIN)
The diagnostic path typically includes physical
examination, diagnostic blood tests, and bone
marrow biopsy. The physical examination may
reveal SPLENOMEGALY (swollen SPLEEN) and LY M-
PHADENOPATHY(swollen lymph nodes). Characteris-
tic patterns of abnormal cell counts and structures
identify the different types of leukemia. In addi-
tion to abnormalities in the leukocytes, depletion
of erythrocytes and platelets is common. Bone
marrow biopsy confirms the diagnosis. Specialized
laboratory tests, such as cytologic examination
and immunophenotyping, establish the character-
istics of the abnormal cells to identify the type of
leukemia.Treatment Options and Outlook
Treatment regimens for leukemia vary with the
type of leukemia, the person’s age, and the per-
son’s general health status aside from the
leukemia. Chemotherapy andRADIATION THERAPY,146 The Blood and Lymph