Chronic neutrophilic leukaemia (CNL)
Chronic neutrophilic leukaemia (CNL) is a type of blood cancer. It affects white blood cells called neutrophils. On this webpage, we cover what it is, the signs and symptoms and how it is diagnosed and treated.
Summary
- Chronic neutrophilic leukaemia (CNL) is a very rare blood cancer that affects cells called neutrophils.
- We do not know the exact cause of CNL. It is not because of anything you have or have not done.
- CNL is diagnosed using blood tests and bone marrow tests.
- There are a number of treatment options your haematology team might consider. These might include:
- Hydroxycarbamide
- Interferon alfa
- Targeted medicines
- A stem cell transplant
- Treatment as part of a clinical trial
What is chronic neutrophilic leukaemia (CNL)?
Chronic neutrophilic leukaemia (CNL) is a very rare type of blood cancer called a myeloproliferative neoplasm (MPN). These are slow-growing blood cancers that develop when cells in your bone marrow grow out of control and make too many blood cells.
CNL happens when your bone marrow makes too many white blood cells called neutrophils. This may stop your bone marrow from making enough healthy blood cells.
Who gets CNL?
CNL is very rare. This is why you might not have heard of it before.
It mainly affects people over 60, but it can affect people of any age. It is slightly more common in men than in women.
What causes CNL?
We do not know the exact cause of CNL. It is not because of anything you have or have not done.
People with CNL develop genetic changes in bone marrow cells called stem cells. Stem cells usually make all the blood cells your body needs. The genetic changes mean they don’t work properly.
Most of these changes happen by chance during your lifetime. You do not usually get them from your parents and you cannot usually pass them to any children you have. In most cases we do not know why these genetic changes occur.
Signs and symptoms of CNL
You might not have any symptoms when you are first diagnosed. Your doctor might find out you have it from a blood test for something else.
But you might get signs and symptoms over time, which could include:
Swollen spleen or liver
Bleeding or bruising easily
Extreme tiredness
Losing weight without trying to
Night sweats
Itchy skin
Pain, swelling or redness around a joint (this may look different on black or brown skin)
Bone pain
Skin disorders or problems that can cause a rash of reddish pink lumps on the skin (this may look different on black or brown skin)
Infections that may be severe, last a long time or keep coming back
Bleeding
CNL can cause bleeding problems.
Contact your medical team straight away if you have:
- Nosebleeds, bleeding gums, heavy periods or bleeding after a bone marrow test.
- Blood in your sick or poo. This might look black or tarry.
- Sudden severe headache, dizziness, confusion, fainting, feeling weak or numb, or slurring your words.
Diagnosis of CNL
You’ll have blood tests and bone marrow tests to diagnose CNL. The samples go to the lab for specialist testing.
Blood tests
You’ll have blood tests and bone marrow tests to diagnose CNL. The samples go to the lab for specialist testing.
Bone marrow tests
You may have a bone marrow test to confirm your diagnosis. This involves taking a sample of your bone marrow, usually from the back of your pelvis, with a local anaesthetic.
Lab tests
Your doctor will send your blood and bone marrow samples to the lab for specialist tests. They check what genetic changes your leukaemia cells have.
Other tests you might have
Your team will let you know if you need any other tests or scans.
Treatment for CNL
CNL can be difficult to treat. Because it is so rare, it is difficult for researchers to carry out trials and work out the best treatment for people with CNL. So, at the moment, there are no definite treatment guidelines.
Your haematology team will suggest the most suitable treatment for you based on:
- Your symptoms and test results
- Your age and overall fitness
- Whether or not you have any other medical conditions
- Your preference on how you wish to be treated
There are a number of treatment options they might consider. These include:
Hydroxycarbamide. This is a chemotherapy medicine that helps lower your white blood cell count. It comes as tablets that you take by mouth.
Interferon alfa. This is a medicine that alters the way your immune system works. It helps stop cancer cells from growing and dividing. You have it as an injection.
Targeted medicines used to treat other blood cancers, such as ruxolitinib. These are usually tablets that you take by mouth.
Stem cell transplant. This is where damaged or abnormal blood-forming cells are replaced with healthy ones from a matched donor. A stem cell transplant is intensive, and it is not suitable for everyone. Your team will only consider it if you are fit enough to have one, and a suitable donor is available. This may be a family member. You usually stay in hospital for several weeks to have it.
A clinical trial. This is where new treatments, or different ways of using existing treatments, are tested to find out if they are better than standard treatments. If there is a clinical trial suitable for you, your team should explain what it involves and the risks and benefits of it. It is your choice whether to take part.
Medicines to prevent or treat side effects.
Sometimes, CNL can transform into different types of blood cancer called acute myeloid leukaemia (AML) or chronic myelomonocytic leukaemia (CMML). If this happens, your medical team will let you know what treatment you will have and what to expect.
Sources we used to produce this information
Anil V, Gosal H, Kaur H, Ngassa HC, Elmenawi KA, Mohammed L. Chronic neutrophilic leukemia: A literature review of the rare myeloproliferative pathology. Cureus. 2021 Jun 3;13(6).
Cross NC, Godfrey AL, Cargo C, Garg M, Mead AJ, A British Society for Haematology Good Practice Paper. The use of genetic tests to diagnose and manage patients with myeloproliferative and myeloproliferative/myelodysplastic neoplasms, and related disorders. British Journal of Haematology. 2021 Nov;195(3):338-51.
Elbaz Younes I, Mroz P, Tashakori M, Hamed A, Sen S. Chronic Neutrophilic Leukemia: Advances in Diagnosis, Genetic Insights, and Management Strategies. Cancers. 2025 Jan 12;17(2):227.
Maxson JE, Tyner JW. Genomics of chronic neutrophilic leukemia. Blood, The Journal of the American Society of Hematology. 2017 Feb 9;129(6):715-22.
Szuber N, Orazi A, Tefferi A. Chronic neutrophilic leukemia and atypical chronic myeloid leukemia: 2024 update on diagnosis, genetics, risk stratification, and management. American journal of hematology. 2024 Jul;99(7):1360-87.
Thomopoulos TP, Symeonidis A, Kourakli A, Papageorgiou SG, Pappa V. Chronic neutrophilic leukemia: a comprehensive review of clinical characteristics, genetic landscape and management. Frontiers in Oncology. 2022 Apr 14;12:891961.
Tremblay D, Sastow D, Mascarenhas J. CNL and aCML are prognostically distinct: a large National Cancer Database analysis. Blood Advances. 2023 Aug 22;7(16):4400-2.
Venugopal S, Mascarenhas J. Chronic neutrophilic leukemia: current and future perspectives. Clinical Lymphoma Myeloma and Leukemia. 2019 Mar 1;19(3):129-34.
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This information is aimed at people in the UK. We do our best to make sure it is accurate and up to date but it should not replace advice from your health professional. Find out more about our information.
Page last reviewed: 31 December 2025
Updated January 2026
Next review due: 31 December 2028
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