In addition to the blood count and bone marrow biopsy, a number of other tests will help determine the patients’ best treatments and their prognosis.
- Lumbar puncture: Lumbar puncture with analysis of the cerebrospinal fluid is an important test as it will determine if the leukaemia cells have penetrated the CNS. If leukaemia cells are present in the CNS, patients will need additional treatment straight after diagnosis.
- For lumbar puncture, patients are asked to lie on their side with their legs pulled up and tucked under the chin. This position makes it easier for the doctor or nurse to insert the needle between the vertebrae.
- After the skin has been cleaned and the area numbed with a local anaesthetic, the thin aspiration needle is inserted between two vertebrae in the lower part of the spine (Figure 9). The patient should not be in pain, but might feel some pressure.
Figure 9 Lumbar puncture and collection of CSF for analysis
Courtesy of Medical gallery of Blausen – commons.wikimedia.org/w/index.php?curid=27796935
- At the end of the procedure, the needle is removed and a small plaster or dressing applied.
- Chromosome abnormalities or gene mutations tests –Chromosome abnormalities and gene mutations are seen in both B-cell and T-cell ALL. The following test can be used to reveal them:
- Standard cytogenetic (study of chromosomes) analysis: The leukaemia cells are examined in the laboratory while they are dividing to show any chromosome abnormalities and gene mutations.
- Molecular cytogenetic analysis, such as FISH (fluorescence in situ hybridisation), in which small portions of DNA are labelled in the laboratory with fluorescent dye to detect DNA sequences. FISH can identify the specific location of the gene on a chromosome, how many copies of the gene are present, and any chromosomal abnormalities.
- An important chromosome abnormality in B-cell ALL is the Philadelphia chromosome, because it has implications for the treatment and prognosis. The Philadelphia chromosome is seen in a number of different blood cancers, including AML, and is much more common in adults than in children.
- Immunophenotyping is a process that analyses the types of markers or antigens on the surface of the leukaemia cells in the patient’s blood. This process is used to diagnose specific types of leukaemia and lymphoma by comparing the cancer cells to normal cells of the immune system.
B-cell or T-cell markers detected by immunophenotyping typically include: - CD19, CD20, CD22 and CD 24 in B-cell ALL
- CD4,CD5, CD7 and CD8 in T-cell ALL
- Imaging tests – X-rays, ultrasounds or scans including computer tomography (CT) and magnetic resonance imaging (MRI) are performed to assess the impact of the leukaemia on the organs of the body.
- Blood tests, bone marrow samples and scans will be repeated throughout treatment to monitor response to treatment.
