Juvenile myelomonocytic leukaemia (JMML)
This page gives information about juvenile myelomonocytic leukaemia (JMML). There is information about
Leukaemia means a cancer of the blood forming system. The blood forming system is the bone marrow - the soft inner part of your bones.
Most types of leukaemia cause abnormal white blood cells to be made in the bone marrow. These cells then get into the blood stream and circulate around the body. They do not work normally and so do not give you the protection from infection that white blood cells should.
Several types of leukaemia can develop in adults and children, but there are two main groups
Juvenile myelomonocytic leukaemia (JMML) is a very rare type of slowly developing (chronic) leukaemia that occurs in children. It is also sometimes called juvenile chronic myelogenous leukaemia (JCML).
JMML is most common in children under 4. As with many types of cancers, we do not yet know the cause of JMML. Children with a genetic disorder called neurofibromatosis 1 (NF1) are more at risk of developing JMML. But this only accounts for about 1 in 10 cases.
In order to understand why leukaemia affects you the way it does, it helps to understand how blood cells are normally produced and what they do. Normally, blood cells are produced in the bone marrow. They are made in a controlled way, when your body needs them. All blood cells start as the same type of cell, called a stem cell. Stem cells then develop into either a myeloid stem cell or a lymphoid stem cell. Myeloid stem cells eventually develop into red blood cells, platelets and a type of white blood cell called granulocytes. The type of leukaemia you have tells you which type of white blood cell has become cancerous. If myeloid cells become cancerous the type of leukaemia is known as a myeloid leukaemia. JMML is a type of myeloid leukaemia.
There is more information about the blood and circulation in the about cancer section of CancerHelp UK. There is more information about the blood and chronic leukaemia and the blood and acute leukaemia in CancerHelp UK.
As the leukaemia cells multiply in the bone marrow, fewer normal blood cells are made. If there are not enough normal blood cells the body cannot work normally. This can cause quite severe symptoms in children with JMML including
- Being tired and lethargic
- Bruising easily
- Nosebleeds and bleeding gums
- Fever
- Getting lots of infections
- Enlarged liver and spleen
- Swollen lymph nodes
- Skin rashes
- Small yellowish skin tumours
The treatment for JMML is usually a stem cell transplant. This is where doctors replace the damaged stem cells with healthy ones taken from a donor, often a brother or sister. At the moment this is the only type of treatment that can possibly cure JMML. Unfortunately, this type of treatment is only suitable for some children. Doctors and scientists are trying to find a more effective treatment for this disease as sadly, it is still difficult to cure.
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