What is hairy cell leukaemia?

In hairy cell leukaemia there 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 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.

In hairy cell leukaemia the abnormal white blood cells build up in the spleen and cause it to enlarge. The enlarged spleen can also remove normal blood cells 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 makes up 2-5% of all types of leukaemia. It is found mostly in people between 40 and 60 years old and is more common in men than women. The condition usually develops very slowly, so the term chronic is used to describe it.

What causes hairy cell leukaemia?

The causes of hairy cell leukaemia are not known. 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 often may 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. Other 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 there is a shortage of healthy white blood cells that normally destroy bacteria. 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 different conditions other than leukaemia, but any symptoms that get worse or last for a few weeks should always be checked by your doctor.

How is it diagnosed?

Your doctor 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. The doctor at the hospital will take your full medical history, do a physical examination and 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 bone marrow to examine under a microscope. This helps to give more specific information about the condition.

The sample is usually taken from the hipbone (pelvis), or occasionally the breastbone (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) and this 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.

Types of treatment

Hairy cell leukaemia is a very treatable disease. Quite often, as it is slowly 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 you are starting to get symptoms. There are several ways of treating hairy cell leukaemia: these include chemotherapy using Cladribine (Leustat) or deoxycoformycin (Pentostatin).

Splenectomy (removal of the spleen) and interferon may also be used.

When treatment is needed, your doctor is most likely to suggest treatment with drugs (chemotherapy). Surgery is less commonly used.

Chemotherapy

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

Cladribine (Leustat). The drug is given as a drip (intravenous infusion) or as injections under the skin, usually every day for 7 days. 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 headache, weakness, feeling sick,  skin rashes and muscular aches. It is important to discuss with your doctor any side effects that you have.

Deoxycoformycin (Pentostatin). The drug is given as an intravenous injection (an injection into a vein) usually every 2 weeks. Side effects are often mild and include infections, which may need to be treated with antibiotics, and mild feelings of sickness 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 give treatment for them if necessary.

Interferon

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 given as an injection under the skin usually three times a week. The most common side effects are flu-like symptoms such as chills, a high temperature (fever) and aching joints. Simple medicines such as paracetamol will often relieve these effects.

Splenectomy

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 further treatment will be needed following splenectomy.

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 (recurs), your doctors will monitor you with blood tests during your remission.

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

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