Diagnosis:

ALL is diagnosed based on various tests.

Physical Examination

The doctor will examine a patient for signs of enlarged lymph nodes or enlarged liver or spleen. The doctor will also look for any signs of bruising or bleeding.

Blood Tests

A complete blood cell count (CBC), which checks for numbers of white cells, red blood cells, and platelets, is the first step in diagnosing ALL. Patients with ALL generally have a higher than normal white blood count and lower than normal red blood cell and platelet counts.

Blood tests are also performed to evaluate liver, kidney, and blood clotting status and to check for levels of certain minerals and proteins.

Bone Marrow Biopsy

If blood test results are abnormal or the doctor suspects leukemia despite normal cell counts, a bone marrow aspiration and biopsy are the next steps. These are very common and safe procedures. However, because this test can produce considerable anxiety, particularly in children, parents may want to ask the doctor if sedation is appropriate for their child.

• A local anesthetic is given.
• A needle is inserted into the bone, usually the rear hipbone. There may be brief pressure or pain. A small amount of marrow is withdrawn. Marrow looks like blood.
• A larger needle is then inserted into the same place and pushed down to the bone. The health professional will rotate the needle to obtain a specimen for the biopsy. The patient will feel some pressure.
• The sample is then taken to the lab to be analyzed. All the results are completed within a couple of days.

Normal bone marrow contains 5% or less of blast cells (the immature cells that ordinarily develop into healthy blood cells). In leukemia, abnormal blasts constitute between 30 - 100% of the marrow.

Spinal Tap

If bone marrow examination confirms ALL, a spinal tap (lumbar puncture) may be performed, which uses a needle inserted into the spinal canal. The patient feels some pressure and usually must lie flat for about an hour afterward to prevent severe headache. This can be difficult, particularly for children, so parents should plan reading or other quiet activities that will divert the child during that time. Parents should also be certain that the professional performing this test is experienced.

A sample of cerebrospinal fluid with leukemia cells is a sign that the disease has spread to the central nervous system. In most cases of childhood ALL, leukemia cells are not found in the cerebrospinal fluid.

Tests Performed after Diagnosis

Once a diagnosis of leukemia has been made, further tests are performed on the bone marrow cells:

• Cytochemistry, flow cytometry, immunocytochemistry, and immunophenotyping tests are used to to identify and classify specific types of leukemia. For example, cytochemistry distinguishes lymphocytic leukemia cells from myeloid leukemia cells. Immunophenotyping shows if ALL cells are T cells or B cells based on the antigen located on the surface of the cell.
• Cytogenetics and fluorescent in situ hybridization (FISH) are used for genetic analysis. Cytogenetic testing can detect translocations (such as Philadelphia chromosome) and other genetic abnormalities. FISH is used to identify specific changes within chromosomes. Genetic variations may help determine response to treatment.

An antigen is a substance that can provoke an immune response. Typically, antigens are substances not normally present in the body.

Cell Classification

The results of cytogenetic, flow cytometry, immunophenotyping, and other tests can help provide information on types and subtypes of ALL cells. The particular subtype of cell can aid in determining prognosis and treatment.

An older classification system called the French-American-British (FAB) classification grouped ALL into L1, L2, and L3 subtypes. A newer classification system classifies ALL B cells or T cells based on their stage of maturity.

B-Cell ALL Subtype Classfication:

• Early Pre-B
• Common ALL
• Pre-B ALL
• Mature B-cell ALL (Also called Burkitt leukemia)

T-Cell ALL Subtype Classifcation:

• Pre-T ALL
• Mature T-cell ALL