Chronic myelomonocytic leukaemia is a rare type of leukaemia, which is tends to affect people in later life. There is a childhood form called JMML, but this is extremely rare.

Leukaemia is a cancer of the blood. It affects the white blood cells, which are a really important part of our immune system that fights infection.

What is chronic myelomonocytic leukaemia?

Chronic myelomonocytic leukaemia is a type of chronic leukaemia meaning it develops slowly, often over many years. It affects a type of white blood cell called monocytes.

What are the signs and symptoms?

Because chronic myelomonocytic leukaemia is a chronic disease that develops gradually the symptoms are not always obvious at first. Many patients will not have any symptoms at the time they are diagnosed – usually while having a routine blood test for some other illness.

The symptoms of chronic myelomonocytic leukaemia are very non-specific and can be confused with those of other common illnesses such as flu.
The most common symptoms include:

• Tiredness and fatigue
• Weight loss
• Fever or night sweats
• Frequent and persistent infections
• Unusual bruising or bleeding
• Abdominal pain due to enlarged spleen

These symptoms are caused by a lack of healthy red and white cells and platelets in the blood. Patients may only experience some of these symptoms.

What causes it?

There is no single factor known to cause chronic myelomonocytic leukaemia. In most cases it is probably due to a combination of different factors.

How common is chronic myelomonocytic leukaemia?

Chronic myelomonocytic leukaemia is rare and accounts for only a small percentage of all leukaemias. Around 300 people are diagnosed with CMML in the UK every year.

It is a generally a condition of later life, although there is a childhood form, called juvenile myelomonocytic leukaemia (JMML), which is also extremely rare.

Chronic myelomonocytic leukaemia is more common in men than women.