What is childhood lymphoma?
Lymphoma is the general term for cancers that develop in the lymphatic system. The lymphatic system is made up of a vast network of vessels, similar to blood vessels that branch out into all the tissues of the body. These vessels contain lymph, a colourless watery fluid that carries lymphocytes which are specialised white blood cells that fight infection.
There are two types of lymphocytes: B-lymphocytes and T-lymphocytes (also called B-cells and T-cells). These cells protect us by making antibodies and destroying harmful micro-organisms such as bacteria and viruses.
Lymphoma originates in developing B lymphocytes and T-lymphocytes, which have undergone a malignant change. This means that they multiply without any proper order forming tumours, which are collections of cancer cells.
Over time, malignant lymphocytes (called lymphoma cells) crowd out normal lymphocytes and eventually the immune system becomes weakened and can no longer function properly.
There are 43 different sub-types of lymphoma currently recognised by the World Health Organization’s classification system for lymphoma. Five of these sub-types belong to a group of diseases called Hodgkin lymphoma. Hodgkin lymphoma is distinguished from all other types of lymphoma because of the presence of a special kind of cancer cell called a Reed-Sternberg cell, which can be seen when examining the tumour cells under a microscope.
All other sub-types are commonly grouped together and called non-Hodgkin lymphoma (or B and T cell lymphomas). In children, lymphoma is one of the most common types of cancer seen, but few children overall are ever diagnosed with these diseases. Lymphomas in children tend to grow quickly but generaslly respond very well to treatment.
Significant advances are continually being made in the way we manage lymphomas. This means that with treatment, many children can now be cured. Many others who are treated remain disease-free and well for a long time.
How common is childhood lymphoma?
In Australia, around 30 children (0-14 years) are diagnosed with Hodgkin lymphoma and around 40 children (0-14 years) are diagnosed with non-Hodgkin lymphoma each year.
Who gets childhood lymphoma?
Hodgkin lymphoma can occur at any age but it is most common in adolescents and young adults. Hodgkin lymphoma is rarely seen in children less than five years old, and it occurs more frequently in males than in females.
Similarly to Hodgkin lymphoma, non-Hodgkin occurs more frequently in males. Non-Hodgkin lymphomas can occur at any age but they are more common in adults over the age of 50, who account for more than 70 per cent of all cases.
What are the causes of childhood lymphoma?
In most cases the causes of childhood lymphoma remain unknown. We do know that it is not contagious and like many cancers, damage to special proteins which normally control the growth and division of cells may play a role in its development. Research is going on all the time into possible causes of this damage and it is thought the alterations in the immune system may play a role in some cases.
Children with a weakened immune system (immunosuppressed) either by a viral infection or as a result of drugs that affect the function of the immune system have an increased chance of developing lymphoma. Infection with Epstein-Barr virus (EBV), the virus that causes glandular fever, may be involved, particularly in people who are immunosuppressed.
In most cases, people who are diagnosed with lymphoma have no family history of the disease. However, there have been some cases where a brother or sister also develops Hodgkin lymphoma, suggesting a rare family genetic link to the disease. As this is very rare, it is not recommended that families undergo testing for the disease.
What are the symptoms of childhood lymphoma?
Some children do not have any symptoms when they are first diagnosed with lymphoma. In these cases the disease may be picked up by accident, for example during a routine chest x-ray for a different complaint. The most common symptom of lymphoma is a firm, usually painless swelling of a lymph node (swollen glands), usually in the neck, under the arms or in the groin.
It is important to remember that most people who go to their doctor with enlarged lymph nodes do not have lymphoma. Swollen glands often result from an infection, for example a sore throat. In this case the glands in the neck are usually swollen and painful.
Other symptoms may include:
- recurrent fevers
- excessive sweating at night
- unintentional weight loss
- persistent fatigue and lack of energy
- generalised itching or a rash
- chronic cough/breathlessness (due to swollen lymph gland in chest)
- bowel changes/blockage (due to swollen glands in abdomen).
These symptoms are also seen in other illnesses such as viral infections. So, most people with these complaints do not have lymphoma. It is important to see your child’s doctor if your child has any symptoms that do not go away so that they can be examined and treated properly.