Symptoms and diagnosis of chronic myelomonocytic leukaemia (CMML)

Some people don’t have symptoms when they are diagnosed with CMML and it is found during a routine test for something else. Others may have symptoms caused by abnormal monocytes building up in the bone marrow and bloodstream, so there is less room for healthy blood cells:

• Low red blood cells (anaemia) can cause breathlessness, pale skin, and tiredness.
• Low platelets (thrombocytopenia) can cause unusual bruising and bleeding
• Low white blood cells can cause frequent infections that last longer than normal.

Having low blood cell counts along with high levels of abnormal monocytes is more common in MD-CMML.

For people with MP-CMML, the main symptoms are caused by high levels of abnormal monocytes and other white blood cells. These blood cells are more likely to spill from the bone marrow into the bloodstream and affect different parts of the body. This can cause symptoms such as:

• a swollen spleen, which might cause you to feel uncomfortable around the upper left side of your stomach, or feel full after eating a small amount
• skin changes, including lumps, rashes, or itching
• bone, muscle, or joint pain
• a swollen liver
• swollen lymph nodes
• night sweats
• fluid in the lungs, which might cause breathlessness
• a general feeling of being unwell, including fatigue (feeling extremely tired) and weight loss – this is because it takes energy to produce such high numbers of white blood cells.

If you notice any of the symptoms above, it’s a good idea to make an appointment with your GP. The symptoms are usually explained by something else that isn’t cancer, but it is important to see a doctor to make sure.

Doctors will use tests to find out the correct diagnosis. They will be looking for certain things to confirm whether you have blood cancer, and whether it is CMML or another type. These things include:

• a consistently high level of monocytes in your blood and bone marrow
• lower than 20% (1 in 5) blast cells in your blood and bone marrow
• no sign of other related conditions when looking at your blood under a microscope
• certain genetic changes (mutations) that show up genetic tests.

Doctors will take a sample of your blood and count how many of each type of blood cell you have. This is called a full blood count. You might need several blood tests over time.

To take a blood sample, a doctor or nurse will insert a small needle into a vein in your arm and draw out a small amount of blood.

Your sample will then be sent to a laboratory, where a haematologist (a doctor who specialises in blood conditions) will count how many platelets, red blood cells and white blood cells are in your body. They will also count the proportion of abnormal monocytes and blast cells in your blood.

Doctors will also look at your blood sample under a microscope to look more closely at the abnormal cells. This is known as a blood smear.

Doctors may also take a sample of your bone marrow. You may hear this called a bone marrow biopsy. A doctor or nurse will use a needle to take a sample of bone marrow from your hip bone (pelvis). You will have a local anaesthetic to numb the area beforehand.

A haematologist will then look at your bone marrow sample under a microscope and look for any abnormal cells.

Some people find the bone marrow biopsy uncomfortable, and some people don’t. Your team will be there to give you support and pain relief, as well as answer any questions you might have.

It normally takes 1-2 weeks to get the results of a bone marrow biopsy.

We have more information about bone marrow biopsies. You can also call our Support Service nurses if you want to talk things through.

Doctors might do some further testing on your bone marrow or blood samples to confirm the diagnosis and decide your risk level.

Immunophenotyping (also known as flow cytometry) looks at proteins on the surface of cells in a blood or bone marrow sample. Certain patterns in these proteins can show that CMML is the right diagnosis. The test can also show which type of CMML you have. It’s a very sensitive test and can find abnormal cells even if the numbers are very low.

Doctors may use tests to look for genetic changes (mutations) in the abnormal cells found in your blood or bone marrow samples:

• Cytogenetic tests look for abnormal patterns in the chromosomes of cells. Chromosomes contain DNA, which is made up of genes.
• Next Generation Sequencing (NGS) looks at many pieces of DNA at the same time. It can give more detailed information about genetic mutations than cytogenetic testing.

These tests can help confirm whether you have CMML and give more information about your risk level. You risk level is a guide to whether the CMML needs to be treated yet, and what the best treatment plan is for you.

If you are diagnosed with CMML, your hospital team will look at a range of things to decide your risk level and what treatment you should have. These include:

• whether you have CMML-1 or CMML-2, based on how many blast cells you have in your blood and bone marrow.
• your white blood cell count, including whether you have MP-CMML or MD-CMML
• whether you need red blood cell or platelet transfusions.
• information from genetic tests.

They will also consider your age, fitness level, and any other health conditions you may have. They will use all this information to calculate a risk score.

A risk score is just a guide, and can’t predict your personal experience of CMML. But having a risk score can help doctors understand more about what is likely to happen in the future (your prognosis) and discuss your the best treatment options with you. Your individual situation and wishes will also be considered when you discuss possible treatments.

It can be hard to take in information about your risk level when you are first diagnosed, so if you are told something that worries you or that you don’t feel you understand, ask your hospital team to explain it again. You can also call our Support Service nurses on 0808 2080 888 or complete this web form for support by email.