Leukaemia is a cancer of the white blood cells; these cells are produced by the bone marrow. There are a number of different types of leukaemia.


Leukemias are divided into two main groups acute and chronic and then further divided by the type of white blood cell which is affected. Acute leukemias come on suddenly, often within days or weeks, progressing quickly and need to be treated urgently. Chronic leukemias develop more slowly often over many months or years.

Hairy cell leukaemia:

This information is about a rare type of chronic lymphocytic leukaemia (CLL), known as hairy cell leukaemia. It should ideally be read with our information about CLL which discusses some of the issues facing people living with leukaemia.


Blood cells

Leukaemia is a general term for an overproduction of white blood cells. To understand the effect of leukaemia on the body, it helps to know about the normal process of blood cell production.

Blood cells all follow the same pattern of development. They form in the bone marrow (the spongy part inside some bones) and then pass into the blood.

There are three types of blood cell:


Red blood cells, which contain haemoglobin (Hb) to carry oxygen around the body

Platelets, which help to prevent and stop bleeding

White blood cells, which fight infections.


There are two main types of white cell: neutrophils and lymphocytes, which work together to fight infection in the body.

A diagram showing the lymphatic system

Lymphocytes circulate in the lymphatic system, the body’s natural defence against infection. The lymphatic system is made up of a collection of lymph nodes (glands) linked by a network of lymphatic vessels. Lymph nodes are found all over the body: The tonsils and the spleen also form part of the lymphatic system.

The spleen is an oval-shaped organ that lies behind the stomach. It produces small numbers of lymphocytes and destroys older, damaged blood cells. The spleen is not essential to life, and its functions can be taken over by other organs if it is removed.


Hairy cell leukaemia

In leukaemia, the normal pattern of white cell development is disrupted and too many immature white blood cells are produced. Over time, the bone marrow slowly becomes taken up with production of these abnormal white cells, and so the number of normal white blood cells, red cells, and platelets that can be produced is lowered.

Hairy cell leukaemia is an overproduction of one type of white blood cell: the B-lymphocyte. The term 'hairy cell' refers to the hair-like outgrowths (projections) that can be seen on the surface of the white cells when they are examined under a microscope.

In hairy cell leukaemia, the abnormal white blood cells build up in the spleen and cause it to enlarge. The enlarged spleen may also cause normal blood cells to be removed from the bloodstream, which can lead to a further lack of red blood cells and lower numbers of normal white blood cells.

Hairy cell leukaemia is very rare and only accounts for 2–5 in 100 of all cases of leukaemia. It is found mostly in people aged between 40 and 60, and is more common in men than women. The condition usually develops very slowly, so the term 'chronic' is used to describe it.



The causes of hairy cell leukaemia are unknown. Hairy cell leukaemia, like other cancers, is not infectious and cannot be passed on to other people.

Signs and symptoms

Since hairy cell leukaemia normally develops slowly, it may not cause symptoms for a long time, and may often only be diagnosed after a blood test has been taken for other reasons.

When hairy cell leukaemia causes symptoms, these can be general, such as weakness, weight loss, infections and breathlessness. Some people see their doctor because they feel tired or look pale due to a lack of red blood cells (anaemia). Some people get frequent infections because they have a shortage of healthy white blood cells that normally fight off infections. Others will be able to feel a full or tender lump on the left side of the abdomen, due to an enlarged spleen.

These symptoms can be caused by a number of conditions other than leukaemia, but any symptoms that get worse, or last for a few weeks, should always be checked by your doctor.

How it is diagnosed

Your GP will examine you and do a blood test. Depending on the result, you will then be referred to a hospital for specialist advice and treatment. You will normally see a haematologist (a doctor who specialises in illnesses of the blood). The haematologist at the hospital will take your full medical history, carry out a physical examination, and take further blood tests.

The blood tests will show the number of abnormal white blood cells, and the typical appearance of 'hairy' cells may also be seen in the blood sample. People with hairy cell leukaemia may also have low numbers of platelets and red cells. You will have regular blood tests throughout your treatment, to check the number of normal cells in your blood (this is known as a blood count). Other blood tests may also be used to check your general health.

The spleen becomes enlarged in most people with hairy cell leukaemia, and the doctor will usually be able to feel this when doing a physical examination.

Bone marrow sample/biopsy

If a blood test shows abnormal blood cells, the hospital doctor will normally want to take a sample of your bone marrow to examine under a microscope. This helps to provide more specific information about the condition.

The sample is usually taken from the hip bone (pelvis), or occasionally the breast bone (sternum). The bone marrow sample is taken under a local anaesthetic. You are given a small injection to numb the area, and a needle is then passed gently through the skin, muscle, and bone. A tiny sample of bone marrow is drawn out using a syringe. Sometimes a small core of marrow is needed (a trephine biopsy), which takes a few minutes longer.

The test may be done on the day ward or in the outpatient department. The procedure can be uncomfortable and even painful at times, but only takes about 15 minutes. Sometimes you may be prescribed a sedative beforehand, to help to relax you during the test. After the test, you will feel bruised and you will be given painkillers to take until the pain or soreness has gone.



Hairy cell leukaemia is a very treatable disease. Quite often, as it is slow-growing, it does not need to be treated straight away. If you do not need treatment immediately your doctor will still monitor you by doing regular blood tests.

Your doctor will recommend treatment when there are signs that the number of abnormal white cells in the body is increasing, or if you start to get symptoms. There are several ways of treating hairy cell leukaemia; the most common treatment is chemotherapy using drugs such as cladribine or pentostatin.

Splenectomy (removal of the spleen) and interferon may also be used, although these are used less often than chemotherapy.


Chemotherapy is the use of anti-cancer (cytotoxic) drugs, which work by stopping the leukaemia cells from multiplying. Cladribine and pentostatin can often get rid of all signs of the leukaemia for some time. This is known as a remission.

Cladribine (Leustat®) The drug is given as a drip (intravenous infusion), every day for seven days usually. This may be repeated. Common side effects include a high temperature (fever) and infection, which will need to be treated with antibiotics. Other possible side effects include headaches, weakness, feeling sick (nausea), skin rashes, and muscular aches. It is important to discuss any side effects that you have with your doctor, as medicines can be given to reduce them.

Pentostatin (Nipent®) The drug is given as an intravenous injection (an injection into a vein), usually every two weeks. Side effects are often mild and include infection,, which may need to be treated with antibiotics, and mild feelings of (nausea), which is usually well controlled with anti-sickness drugs. Other possible side effects include skin rashes, high temperatures (fever) and temporary changes in kidney function. Your doctor will give you advice about how to cope with any side effects you have and can give treatment for them if necessary.


Interferon is a type of immunotherapy, which means that it boosts the body’s own immune system. The exact way in which interferon works in hairy cell leukaemia is not fully understood, but it is thought that it may help to activate the body’s immune system and that it may also work directly against the cancer cells. The drug is usually given three times a week, as an injection under the skin. The most common side effects are flu-like symptoms such as chills, a high temperature, and aching joints. Simple medicines such as paracetamol can often relieve these effects.


Splenectomy is the surgical removal of the spleen. For some people who have an enlarged spleen, removing it can help to reduce symptoms. However, the illness will still be present and further treatment is usually necessary. In a small number of people, no treatment will be needed following splenectomy.

After treatment

The aim of treatment for hairy cell leukaemia is to bring about a remission, which means that the disease is inactive or dormant, although it may still be present. The remission may last for several years. However, as hairy cell leukaemia usually comes back, your doctors will monitor you with blood tests during your remission. If you feel unwell at any time between these appointments, it is important to let your doctor know as soon as possible.


If the leukaemia does come back, your doctor will discuss another course of treatment with you. Doctors cannot predict how long the leukaemia will stay in remission, but with current treatments hairy cell leukaemia can be controlled for long periods.

Clinical trials

Research into treatments for hairy cell leukaemia is ongoing and advances are being made. Cancer doctors use clinical trials to assess new treatments. Before any trial is allowed to take place it must have been approved by an ethics committee, which checks that the trial is in the interest of patients.

Your doctor must discuss the treatment with you so that you have a full understanding of the trial and what it involves. You may decide not to take part, or to withdraw from a trial, at any stage. You will then receive the best standard treatment available.


The need for practical and emotional support will of course be individual. Some people with hairy cell leukaemia may find that their life is largely unaffected; for others the diagnosis of cancer may be a source of great fear and distress.

You may have many different emotions including anger, resentment, guilt, anxiety and fear. These are all normal reactions, and are part of the process many people go through in trying to come to terms with their illness.