Diagnosis of Acute Lymphocytic Leukemia

Executive Summary

Several diagnostic tests are necessary to diagnose the acute lymphocytic leukemia. The main procedures to diagnose acute lymphocytic leukaemia are a patient’s medical history, complete blood cell count, physical examination, and bone marrow aspiration. The common diagnostic tests for acute lymphocytic leukaemia include blood tests, bone marrow aspiration and biopsy, laboratory testing for the identification of specific genes, proteins, and other factors unique to the leukaemia, flow cytometry (immunophenotyping and cytochemistry), Karyotyping, or cytogenetics, molecular assays, lumbar puncture (spinal tap), and imaging tests (Computed tomography (CT or CAT) scan, Magnetic Resonance Imaging (MRI)).

Diagnosis of Acute Lymphocytic Leukemia

Several tests are necessary to find or diagnose cancer. They also do tests to see if cancer has spread to another part of the body from where it began and if this is metastasis. For instance, imaging tests can represent if cancer has spread. Imaging tests show pictures of the body from the inside.

A biopsy is the sure short way for the doctor to know if an area of the body has cancer for most types of cancer. In a biopsy, the doctor takes a tissue sample for testing in a laboratory. The doctor may also suggest other tests if the biopsy is unclear.

The doctor may consider given factors when choosing a diagnostic test:

• The age and general health status
• The type of cancer suspected
• The result of earlier medical tests
• Your signs and symptoms

In addition to a physical examination, the below-mentioned tests can also help diagnose Acute lymphocytic leukemia ^​1​.

Blood tests

If your doctor suspects that you have ALL based on the symptoms, they may do a complete blood count (CBC) test. This test evaluates the levels of different types of cells in the blood.

Low levels of red blood cells (RBC) and platelets are typical in people having ALL, as are high, low, or normal levels of white blood cells(WBC). Modifications in blood cell levels can also signify another medical problem, not leukemia. A blood test can also help to determine lymphoblasts or other abnormal cells.

Bone marrow aspiration and biopsy

If the blood test shows abnormalities in the count or appearance of the WBC, you may require a bone marrow aspiration and biopsy ^​2​. The two procedures are similar and often done simultaneously to evaluate the bone marrow, which is the fatty, spongy tissue found inside larger bones. Bone marrow has both a liquid and a solid part. A bone marrow aspiration takes a sample of the fluid using a needle. A bone marrow biopsy removes a small quantity of solid tissue using a needle. 

A pathologist analyzes the sample removed during a bone marrow aspiration and biopsy. The sample is to check for leukemia, and molecular testing and immunophenotyping can also be a part of it. The common site for a bone marrow aspiration and biopsy is the pelvic bone located in the lower back by the hip. Medication can help the skin in that area to remain numb before the test.

Other testing

The doctor may recommend running laboratory tests on the leukemia cells to identify specific genes, proteins, and other factors unique to leukemia. These tests will help decide whether the treatment options include a type of treatment called targeted therapy.

Flow cytometry, also known as immunophenotyping and cytochemistry

These tests use chemicals or dyes on the cancer cells to learn more about leukemia and its subtype ^​3​. ALL cells have characteristic markers on their surface called cell surface proteins. Immunophenotype is the pattern of these markers. These tests are helpful to distinguish ALL from healthy blood cells and other types of leukemia, which can involve lymphocytes.

Karyotyping, or cytogenetics

This test examines a cell’s chromosomes (long DNA pieces containing genes). People with ALL may have specific chromosomal changes, such as adding or losing specific chromosomes and translocations ^​4​. For instance, fluorescence in-situ hybridization (FISH) is a special test that will help to find these changes. Around 25% of patients have a normal karyotype when diagnosed with acute lymphocytic leukemia.

About 20% to 30% of adults with ALL have a specific chromosome change known as the Philadelphia chromosome. The Philadelphia chromosome is an example of a small chromosome caused due to translocation. In this case, it means that genetic material from chromosome 9 breaks off and gets attached to chromosome 22 [t(9;22)]. Then, two specific genes called BCR and ABL join to make one gene called BCR-ABL. Some people can have other types of translocations. For instance, many children with ALL have a translocation between chromosomes 12 and 21 [t(12;22)]. These genes are called TEL and AML1.

Molecular assays

These tests may find mutations in genes that is not visible under a microscope or found with cytogenetic tests. For instance, patients with changes in the IKZF1 gene have a poorer long-term prognosis, which is the chance of recovery. Therefore, testing for these changes during diagnosis can help determine the treatment options.

Lumbar puncture (spinal tap)

A lumbar puncture is a procedure that uses a needle to take a sample of cerebral spinal fluid to look at the make-up of the fluid and to determine if it contains cancer cells or blood.

ALL tends to spread to the Cerebrospinal fluid, which is the fluid that flows around the brain and the spinal cord. This means that lumbar punctures are performed regularly during ALL treatment. Also, chemotherapy may be given in the CSF. Doctors generally give an anesthetic to numb the lower back before the procedure.

Imaging tests

The below-mentioned imaging tests may help to learn more about the cause of symptoms and help diagnose infections in patients with acute lymphocytic leukemia.

Computed tomography (CT or CAT) scan

A CT scan takes pictures of the body from the inside using x-rays taken from different angles. A computer then combines these pictures into a detailed, 3-dimensional image showing abnormalities of the tumor. A CT scan can help to determine the from the tumour’s size. Occasionally, a specific dye called a contrast medium is given before the scan to provide detail on the image. This dye can be delivered into a patient’s vein or provided as a pill or liquid to swallow.

Magnetic Resonance Imaging (MRI)

An MRI uses magnetic fields, not x-rays, to produce detailed body images. MRI can also help to determine the tumor’s size. A specific dye called a contrast medium is given before the scan to form a clearer picture. This dye can be delivered into a patient’s vein or given as a pill or liquid to swallow.

Positron emission tomography (PET) or PET-CT scan

PET scan creates images of organs and tissues present inside the body. A small quantity of a radioactive substance is injected into the patient’s body which is taken up by cells using the most energy. The cancer cells which use energy actively take up the radioactive substance, and the scanner then spots this substance to produce images of the inside of the body. However, the radioactivity in the substance is significantly less to be harmful to patients. A scanner then detects this radioactive substance to produce images of the inside of the body.

References