Childhood leukaemia – How is it diagnosed?
This is a cancer of the white blood cells that are produced in bone marrow, the spongy central area of bone where all blood cells are made. In leukaemia, the bone marrow makes excess abnormal immature or baby white blood cells. These cells grow out of control and enter the blood. They are unable to fight infections and may aggregate or gather in certain organs like the lymph nodes, liver, spleen, skin, testes, and brain.
In addition, the bone marrow becomes packed with these abnormal cells, leaving no space to produce normal red blood cells, platelets, and other white blood cells. This leads to the common symptoms: tiredness and pallor due to anaemia or low haemoglobin, bleeding and abnormal bruising due to low platelets, bone pain from the abnormal cancer cells that congregate in the bone marrow, and fever due to infection. Children may also present with enlarged lymph nodes or glands, and an enlarged liver and spleen.
Suspecting leukaemia and referrals
These symptoms become worse over time and these children are then seen by either a GP or paediatrician. When a doctor suspects leukaemia, they order a blood test called a full blood count. This usually shows abnormalities in the number of white blood cells, low haemoglobin, and a low platelet count. The laboratory looking at the blood sample will often, but not always see the abnormal leukaemia cells.
These children are then referred to a paediatric oncologist or haematologist. They will then undergo a bone marrow aspiration and trephine. A needle is inserted into the back of the hip bone and bone marrow is aspirated or sucked out with a syringe. This is sent to the laboratory for further testing.
A second needle is used to remove a small piece of the hip bone which is also sent to the laboratory. There is no cut made on the child’s back and there are no stitches. Because this procedure is painful, most children will have a general anaesthetic.
If the child’s platelet count is very low, the child may receive a platelet transfusion to decrease the risk of bleeding associated with the procedure. In addition to the bone marrow, a lumbar puncture also needs to be performed. This is a procedure to collect and look at the cerebrospinal fluid (CSF) surrounding the brain and the spinal cord.
Leukaemia cells may sometimes occur in the CSF and it’s important to know this because it can change the treatment. Most children are admitted in hospital for the bone marrow. Results usually take about 24 hours to come back. The results allow doctors to find out the type of leukaemia and start the most appropriate treatment.
Childhood cancer is rare and comprises less than 1% of all malignant disease. It occurs in about 1 in 650 children, or 140 children per million. It’s estimated that almost half the children with cancer in SA will never be diagnosed.
The most common types are as follows:
- Leukaemia 34%
- Brain tumours 22%
- Lymphoma 11%
- Nephroblastoma 6%
- Neuroblastoma 6%
- Soft tissue sarcoma 6%
- Bone tumours 5%
Dr Kate Bennett is a paediatric oncologist; she qualified as a paediatrician in 2009 and then as a paediatric oncologist in 2011. She has a special interest in the treatment of paediatric leukaemia and lymphoma, immune thrombocytopaenia, and sickle cell anaemia.
Header image by Freepik
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