Leukemia Diagnosis.

For leukemia diagnosis all leukemia patients should have a complete initial history, physical examination, and general laboratory investigation, not only to establish a diagnosis, but to provide a base line for treatment and to learn whether other medical problems are present. Although leukemia may be strongly suspected by the physician on the basis of the patient's history and symptoms, the definitive diagnosis must be made by examination of the cells in the bone marrow. Microscopic observation of a sample of the patient's blood can confirm the doctor's clinical impression, but the blood smear may show only mild, indefinite abnormalities that are not in themselves diagnostic of a particular blood disorder. For a bone marrow test, a sample is obtained by either biopsy or aspiration. Both procedures involve insertion of a thin, hollow needle into a marrow-rich cavity within a bone, usually the back of the hip or the breastbone.

The procedure takes about fifteen to twenty minutes and can be performed under local anesthesia in an outpatient setting or doctor's office. Complications are unusual and although the test may seem frightening, it involves only minimal discomfort. In fact, many patients say they are more disturbed by the sound and idea than by any feeling of actual pain. A lymph node biopsy may be done, but this procedure is usually not required for diagnosis.

The specimen of bone marrow is smeared on slides, stained with certain dyes, and organized and examined under a microscope, usually by a hematologist, oncologist, and pathologist in consultation. The specimen is always abnormal in acute leukemias, containing a greatly increased number of white cells. The cells may be clearly abnormal or they may closely resemble normal cells that have failed to mature from the more primitive "blast" stage into the later adult stage. Chronic leukemias present a similar bone marrow picture, but the cells are somewhat more mature in appearance.
Other blood tests may be performed to determine levels of uric acid, potassium, or calcium, all of which may be altered by the presence of the cancer and, later, by its treatment. In most cases the patient's immune status will be determined by checking the antibody levels in the blood and by a skin testing procedure similar to that used by allergists.

If leukemia is confirmed, immunologic tissue typing, blood typing, coagulation and transfusion studies will be performed. This information is most valuable if acquired before transfusions have made it difficult to test the properties of the patient's own blood. The success of bone marrow transplantation is heavily dependent on tissue typing, which also should be done on the patient's brothers and sisters if this procedure is to be seriously considered.

In difficult cases, special stains may be necessary to confirm the exact diagnosis, especially if the cell type cannot be definitely ascertained or the resemblance to normal cells is very close. Pathologists use many immunologic, chemical, enzymatic, and structural markers, or signs, to ascertain the diagnosis as precisely as possible. An accurate diagnosis is becoming more important as therapy becomes more and more specific. Highly specific antibodies, monoclonal antibodies, have enhanced the ability of pathologists to diagnose leukemias.

Chromosomal studies have assumed an important place not only in the diagnosis of leukemia, but also in helping to monitor the course of the disease as well as the effectiveness of therapy. The chromosomal abnormalities are found in the leukemic white cells, not in normal white cells or in the cells of other organs in the body. Elucidation, prevention, and control of this change is what the ultimate cure of cancer rests on.