Tests for hairy cell leukaemia

You usually have a number of tests to check for hairy cell leukaemia. Your doctor may suspect or sometimes diagnose leukaemia from a blood test. You then have more tests to confirm your diagnosis and find out more about the type of leukaemia you have.

Hairy cell leukaemia is a rare type of chronic leukaemia. It develops slowly from white blood cells called B lymphocytes Open a glossary item.

The 2 most common types of chronic leukaemia are:

  • chronic myeloid leukaemia (CML)

  • chronic lymphocytic leukaemia (CLL)

We have separate information about the tests you might have for CML and CLL.

Tests your GP might do

Hairy cell leukaemia tends to develop slowly, so symptoms can be mild at first. Some people don’t have any symptoms and are diagnosed after having a routine blood test for something else.

People with symptoms that could be due to cancer, usually start by contacting their GP surgery. Your first appointment may be a telephone appointment. Your GP surgery then might arrange for you to go in and see a doctor or other healthcare professional.

Your GP can do some tests to help them decide whether you need to see a specialist. This usually includes:

  • physical examination

  • blood tests

Depending on the results of your examination and blood tests, your GP may arrange for you to have other tests such as an x-ray or ultrasound scan. You usually have these tests at your local hospital.

Physical examination

Your doctor usually asks you to lie or sit down. They look at and feel your skin all over your body to check for any abnormalities or areas that are swollen. Things they look for include signs of bleeding, bruising and infection.

They may also listen to your chest and tummy (abdomen) to find out if they sound normal.

You can ask for someone else to be in the room with you if you want, to act as a chaperone. A chaperone is a trained healthcare professional such as a nurse. A friend or relative can also stay with you for support. They can be with you during the examination.

Blood tests

Blood tests can check your general health including:

  • how well your liver and kidneys are working
  • the number of blood cells in your blood such as white blood cells, Open a glossary item platelets Open a glossary item and red blood cells. You may hear this being called a full blood count Open a glossary item
  • if you have any signs of infection

Tests your specialist might do

Depending on your symptoms and the results of your blood tests, your GP might arrange for you to go to the hospital. Sometimes this is quite quick, and you might have to go there straight away. This can happen if your GP suspects that you have leukaemia.

The specialist you see at the hospital is called a haematologist. This is a doctor who specialises in diseases of the blood such as leukaemia.

Your specialist usually repeats the blood tests done by your GP. You also have more tests such as:

  • tests on blood sample cells. This is also called immunophenotyping
  • a bone marrow test
  • tests to look for changes in the genes Open a glossary item of your leukaemia cells
  • scans such as an ultrasound scan and a CT scan


Immunophenotyping are tests to look for certain proteins on the surface of the leukaemia cells. This is one of the most important tests you have. The results are usually all your doctor needs to confirm a diagnosis of hairy cell leukaemia.

A specialist laboratory does these tests. Sometimes doctors use a technique called flow cytometry to do immunophenotyping.

Immunophenotyping is usually done using blood samples. But your doctors may also use bone marrow samples.

These tests can also help to find out how well treatment is working and if your leukaemia has gone away after treatment.

Bone marrow test

You have this test to check whether there are cancer cells in your bone marrow. The bone marrow is the soft inner part of the bones where new blood cells are made. This can help to find out more about the type of hairy cell leukaemia you have. 

You usually have this test under local anaesthetic. This means that you are awake but the area is numb.

During a bone marrow biopsy, your doctor or specialist nurse removes a sample of bone marrow cells, or an area of bone marrow in one piece. They usually take these samples from the back of your hip bone.

Diagram showing a bone marrow biopsy

A specialist doctor called a pathologist looks at the tissue under a microscope.

Tests to look for changes in the genes

There are different tests that look for changes in the genes of your leukaemia cells. These are also called genetic tests.

Doctors look for changes in specific genes. For example, the BRAF V600E gene. People with typical or classical hairy cell leukaemia usually have a change (mutation) in this gene. This is different for people with hairy cell leukaemia variant (HCL-V).

These genetic tests help your doctor find out more about the type of leukaemia you have and your outlook.


You may have some scans to check for hairy cell leukaemia.

Ultrasound scan

Ultrasound scans use sound waves to create a picture of a part of the body. You might have an ultrasound scan to see if your spleen Open a glossary item or liver is bigger than normal.

CT scan

CT (or CAT) stands for computer (axial) tomography. It is a test that uses x rays and a computer to create detailed pictures of the inside of your body. The computer puts them together to make a 3 dimensional image.

You may have a CT scan of your abdomen to look for changes in your liver and spleen. It can also check if any of your lymph nodes Open a glossary item are swollen (enlarged).


The tests you have help your doctor find out if you have leukaemia and the type of leukaemia you have.

This is important because doctors use this information to recommend the best treatment for you.


Coping with a diagnosis of hairy cell leukaemia can be difficult. There is help and support available for you and your family.

  • Guidelines for diagnosis and management of hairy cell leukaemia (HCL) and hairy cell variant (HCL-V)
    N Parry-Jones and others on behalf of BSH guidelines committee
    British Journal of Haematology, 2020. Vol 191, Issue 5. Pages 730-737

  • Hairy cell leukaemia: ESMO clinical practice guidelines for diagnosis, treatment and follow up
    T Robak and others
    Annals of Oncology, 2015. Vol 26, Supplement 5. V100-V107

  • BRAF mutation in hairy cell leukaemia
    E Tiacci and others
    The New England Journal of Medicine, 2011. Vol 364, Issue 24. Pages 2305-15

  • Routes to diagnosis, 2018
    NHS Digital, 2022

  • Suspected cancer: recognition and referral
    National Institute of Health and Care Excellence (NICE), 2015 (last updated October 2023)

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
02 Apr 2024
Next review due: 
02 Apr 2027

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