Childhood ALL diagnosis
ALL is diagnosed by examining samples of your blood and bone marrow.
Full blood count
The first step in the diagnosis is a simple blood test called a full blood count (FBC) or complete blood count (CBC). This involves a sample of blood from a vein in your arm being sent to the laboratory for investigation. Most people with ALL have a low red cell and platelet count.
Many of the white blood cells may be abnormal leukaemic blast cells. The presence of these blast cells suggests you have ALL. An ALL diagnosis needs to be confirmed by examining the cells in the bone marrow.
Bone marrow examination
If the results of the blood tests suggest ALL, a bone marrow biopsy may be required to help confirm the diagnosis. A bone marrow biopsy involves taking a sample of bone marrow, usually from the back of the hip bone and sending it to the laboratory for examination under the microscope.
The bone marrow biopsy may be done in the haematologist’s rooms, clinic or day procedure centre and is usually performed under local anaesthesia with sedation given either by tablet or through a small drip in your child’s arm. The sample of bone marrow is examined in the laboratory to determine the number and type of cells present and the amount of haemopoiesis (blood forming) activity taking place there.
The diagnosis of ALL is confirmed by the presence of an excessive number of blast cells in the bone marrow.
Cerebrospinal fluid examination
A small sample of the cerebo-spinal fluid (CSF) that surrounds your child’s brain and spinal cord is collected during a procedure called a lumbar puncture, and tested in the laboratory to check for the presence of cancer cells within the central nervous system (CNS).
If cells are found, additional treatment is given to the CNS. The CSF is usually negative but even in this case some CNS directed treatment (CNS prophylaxis) is required as a very small number of cells may be present but not detectable.
Once the diagnosis of ALL is made, blood and bone marrow cells are examined further using special laboratory tests. These include immunophenotyping and cytogenetic tests. These tests provide more information about the exact type of disease your child has, the likely course of the disease and the best way to treat it.
Other tests may be conducted to provide information on your child’s general health and how their vital organs are functioning. These include a combination of further blood tests and imaging tests such as X-rays, scans and ECG.
These results will provide a baseline of your child’s disease and general health which will be compared with later results to assess how well your child is progressing and responding to treatment.