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Cytogenetic analysis
in malignant disease involves the study of the dividing tumor
cells. In leukemia, a bone marrow aspirate is usually obtained
for study. Alternatively, in patients with a high white blood
cell count (>10,000) a sample of peripheral blood may be cultured
without addition of mitogen (i.e., unstimulated cultures). Mitogens
stimulate the division of normal lymphoid cells and may interfere
with the study of spontaneously dividing malignant cells. It
is very important that the laboratory be informed that the peripheral
blood sample is for a leukemic study so that the cells will be
established in unstimulated cultures. When a consistent chromosome
abnormality is detected in unstimulated peripheral blood, it
may be necessary to study cells from stimulated blood to verify
that the chromosome abnormality reflects the tumor cell population
rather than the constitutional karyotype. Whenever a blood sample
is received for an unstimulated analysis, a stimulated culture
is also prepared in the event that it is necessary to determine
the constitutional karyotype.
In addition to routine
chromosome analysis on bone marrow and unstimulated blood, fluorescence
in situ hybridization studies are also available.
The study of chromosome abnormalities in leukemia serves two
functions: first, to assist in a more accurate diagnosis and
second, to provide prognostic information. In leukemia, specific
chromosome abnormalities often correlate with particular subtypes
of disease. Serial samples from the patient permits the study
of cytogenetic patterns during the various stages of a patient's
clinical course.
Clinical information
provided with the patient sample can aid the cytogenetics laboratory
in selecting the appropriate culture method and can alert them
to the potential presence of specific abnormalities. Information that should
be included with a bone marrow or unstimulated blood specimen
include patient name, age, sex, referring diagnosis, clinical
status (diagnosis, residual disease, remission, relapse, exposure
history), presenting CBC, percent circulating immature cells,
bone marrow cellularity, and percent blasts.
Bone Marrow
Specimen requirements: 1 to 5
ml of bone marrow should be aspirated in a sterile syringe coated
with 0.1 ml of sodium heparin. The specimen can be transferred
to a sterile tube for transport. Alternatively, the needle can
be removed from the syringe, the syringe capped, and the specimen
transported in the original syringe. Patient information including
WBC count and suspected diagnosis should accompany the specimen.
Transport: Specimen should be kept
at room temperature; do not freeze or refrigerate. Specimen
should be sent by courier or overnight mail to arrive at the
laboratory within 24 hours.
Analysis: A minimum of 20 cells are
counted and analyzed from G-banded preparations. Hard copies
of two karyotypes and 3 chromosome spreads are retained for documentation.
Report: Results are called to the
referring physician's office in about 3 to 5 days. Final reports
are mailed to the physician's office.
CPT codes: 88237, 88264, 88291, and
possibly 88280
Unstimulated Leukemic Blood
Specimen requirements: 5 to 10
ml of peripheral blood in a sodium heparin Vacutainer™ tube.
Patient information including WBC count should accompany the
specimen.
Transport: Specimen should be kept
at room temperature; do not freeze or refrigerate. Specimen
should be sent by courier or overnight mail to arrive at the
laboratory within 24 hours.
Analysis: A minimum of 20 cells are counted and analyzed
from G-banded preparations. Hard copies of two karyotypes and
3 chromosome spreaReport: Results are called to the referring
physician's office in about 3 to 5 days. Final reports are mailed
to the physician's office.
CPT codes: 88237, 88264, 88291, and
possibly 88280
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