Hairy cell leukaemia variant (HCL-V)

Doctors used to think hairy cell leukaemia variant (HCL-V) was a rare type of hairy cell leukaemia. But they now consider it to be a completely different condition.

HCL-V is a type of chronic leukaemia. It develops from cells called B lymphocytes. 

You might have surgery to remove your spleen (splenectomy). Or you might have treatment with chemotherapy and a targeted drug called rituximab. 

What is hairy cell variant?

You might hear hairy cell leukaemia called 'classic' or 'classical' hairy cell leukaemia. Classic hairy cell leukaemia is a different type of leukaemia to hairy cell leukaemia variant (HCL-V).  

This page is about hairy cell leukaemia variant.

HCL-V and classic hairy cell leukaemia are both chronic leukaemias and they develop slowly from cells called B lymphocytes. 

B lymphocytes are a type of white blood cell that fights infection. When you have hairy cell leukaemia, the body makes too many B lymphocytes. These B cells aren’t normal and can’t fight infections properly. If you look at the cells under a microscope you can see tiny, hair-like, outgrowths on their surface.

HCL-V cells:

  • are usually smaller than classic hairy leukaemia cells
  • have different genetic material in the cells
  • respond differently to treatment

HCL-V is less common than classic hairy cell leukaemia. It can develop at any age, but it is more common in older people.


The symptoms of HCL-V are the same as for classic hairy cell leukaemia. They include:

  • a swollen tummy (abdomen) due to a bigger (enlarged) spleen
  • frequent infections
  • tiredness and breathlessness due to low levels of red blood cells (anaemia)
  • bleeding and bruising due to low levels of platelets (platelets are important for blood clotting)

Getting diagnosed

Your doctor will examine you and arrange blood tests to check your general health. Other tests include:

  • bone marrow tests
  • an ultrasound scan or a CT scan

The blood tests show how many blood cells you have and whether they are normal. Tests usually show a high white blood cell count.

You also have tests to look at the bone marrow cells. The bone marrow tests can show whether you have HCL-V or classic hairy cell leukaemia.

You might have tests to look for anything unusual in the chromosomes of the leukaemia cells. Chromosomes contain the genetic material inside cells. These tests are called cytogenetics (pronounced sigh-toe gen-et-ics).

The ultrasound scan or CT scan will show whether your spleen is enlarged and if you have any swollen lymph nodes.

Treatment options

If you don't have any symptoms you probably won’t need to start treatment immediately. Some people don’t need to start treatment for a number of years. Instead you have regular check-ups. Doctors call this watch and wait.

You have treatment if your blood cell levels change or if you develop symptoms. Your treatment will depend upon:

  • how far your leukaemia has developed
  • your symptoms
  • your general health and level of fitness

Doctors are still trying to find the best treatments for HCL-V.

Treatment options include:

  •  surgery to remove your spleen
  • a targeted drug (such as rituximab) combined with chemotherapy



Many people with HCL-V have an enlarged spleen. The spleen filters the blood and breaks down worn out red blood cells. It also gets rid of bacteria and dead tissue. In HCL-V the spleen can get so clogged up with cells it can’t work properly.

Your doctor might suggest removing your spleen if:

  • the spleen is so large that it is causing pain
  • it is destroying too many red blood cells or platelets

Removing the spleen (splenectomy) can help to control symptoms.

Targeted cancer drugs

Targeted cancer drugs work by targeting the differences in cancer cells that help them to grow and survive.

Rituximab is a type of targeted drug called a monoclonal antibody. It works by searching for a protein that is found on normal and leukaemic white blood cells (lymphocytes). Rituximab sticks to the protein on the cells. The immune system can then target the cells and kill them.

Sometimes, rituximab or a similar drug is combined with chemotherapy.


Chemotherapy means using anti cancer drugs to destroy cancer cells.

You might have a chemotherapy drug called cladribine. You usually have it with rituximab. 

If hairy cell leukaemia variant comes back

Treatment for HCL-V aims to control the cancer for as long as possible. This is called remission. 

If your HCL-V comes back (relapses) after targeted drugs or chemotherapy, you will have more treatment. Treatment depends on:

  • the treatment you had before 
  • the time since your last treatment 
  • your general health and fitness 

If your first treatment doesn't put HCL-V into remission, you might have a different targeted drug. This might be part of a clinical trial. 

Newer treatments

Researchers are looking at other targeted drugs for hairy cell leukaemia. 


Ibrutinib (Imbruvica) is a type of targeted drug called Bruton Tyrosine Kinase Inhibitors (BTKi). You might have this drug as part of a clinical trial. 


These are monoclonal antibodies that have a toxin (type of poison) attached to them. The antibody attaches to a protein on the leukaemia cells and delivers the toxin. The toxin kills the cancer cells. 

Moxetumomab pasudotox is a type of immunotoxin. Research shows that moxetumomab works well for people with HCL. But it's not currently available in the UK as a treatment for hairy cell leukaemia variant. 

Coping with hairy cell leukaemia variant

Coping with a rare condition can be difficult, both practically and emotionally. Being well informed about your condition and its treatment can help you to make decisions and cope with what happens.

The symptoms of HCL-V often mean that you find it hard to do everyday things. Talk to your doctor or nurse about any symptoms you have. There may be supportive treatments that can help you. You may also feel better if you:

  • eat a healthy well balanced diet
  • do some exercise – after checking with your doctor
  • rest when you are tired

If you get tired easily, try to work out your priorities each day. Talk to your family and friends and ask for any help you need. 

Research and clinical trials

Your doctor might ask if you’d like to take part in a clinical trial. Doctors and researchers do trials to make existing treatments better and develop new treatments. But HCL-V is rare. So there are fewer trials compared to some types of cancer. There might not be any clinical trials available. 

Last reviewed: 
20 Oct 2021
Next review due: 
20 Oct 2024
  • Guideline for diagnosis and management of hairy cell leukaemia (HCL) and hairy cell variant (HCL-V)
    N Parry-Jones and others (2020) 
    British Journal of Haematology 2020, Volume 191, pages 730 – 737

  • Hairy cell leukaemia: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    T Robak  and others on behalf of the ESMO Guidelines Committee
    Annals of Oncology, 2015. Volume 26, Supplement 5

  • Diagnosis and classification of hematologic malignancies on the basis of genetics
    J Taylor and others 
    Blood, 2017. Volume 130, Number 4, pages 410 to 423

  • The prognostic impact of clinical and molecular features in hairy cell leukaemia variant and splenic marginal zone lymphoma
    S Hockley and others
    British Journal of Haematology, 2012. Volume 158, Issue 3

  • Immunoconjugates in the management of hairy cell leukemia
    R Kreitman and others 
    Best practice and research: clinical heamatology, 2015. Volume 4, pages 236 to 45

  • Current and Emerging Therapeutic Options for Hairy Cell Leukemia Variant
    Q Liu and others
    OncoTargets and therapy 2021 Volume 14 Pages 1797–1805.

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