T-cell Acute Lymphoblastic Leukaemia

T-cell acute lymphoblastic leukaemia (T-ALL) is a specific type of leukaemia. It is a variant of acute lymphoblastic leukaemia (ALL), with features similar to some types of lymphoma.

T-cell acute lymphoblastic leukaemia (T-ALL) is a type of acute leukaemia meaning that it is aggressive and progresses quickly. It affects the lymphoid-cell-producing stem cells, in paticular a type of white blood cell called T lymphocytes as opposed to acute lymphoblastic leukaemia (ALL) which commonly affects B lymphocytes.

A lymphoid stem cell becomes a lymphoblast cell and then one of three types of lymphocytes (white blood cells):

  • B lymphocytes that make antibodies to help fight infection.
  • T lymphocytes that help B lymphocytes make the antibodies that help fight infection.
  • Natural killer cells that attack cancer cells and viruses.

What causes T-ALL?

In most cases of T-ALL there is no obvious cause but it is important to understand that:

  • It is not a condition which can be caught from someone else (contagious)
  • It is not passed on from a parent to a child (inherited)

Rick factors:

  • Age – most forms of leukaemia are more common in older people. The main exception to this is ALL, in which peak incidence is in children, aged between about 2 to 5yrs. T-ALL is most common in slightly older children
  • Being male – T-ALL affects males more than females at all ages

Signs and symptoms of T-ALL

There are no specific signs or symptoms which would allow a diagnosis of T-ALL to be made. The most common signs and symptoms are caused by the bone marrow being unable to produce enough normal blood cells.

  • Anaemia – due to lack of red blood cells
  • Weakness, tiredness, shortness of breath, light-headedness, palpitations
  • Infections – due to lack of normal white blood cells
  • Infections are more frequent, more severe and last longer
  • Fever, malaise (general feeling of illness) and sweats
  • Purpura (small bruises in skin), nosebleeds, bleeding gums
  • Bleeding and bruising – due to lack of platelets

Other common signs and symptoms include:

  • T-ALL often causes swollen lymph nodes in the middle part of the chest (mediastinum) which may affect breathing or the circulation


Although a doctor may suspect a patient has leukaemia based on signs and symptoms, it can only be diagnosed by laboratory tests. The results of a simple blood count will usually indicate leukaemia although, rarely, a blood count may be normal. Virtually all patients with T-ALL will have bone marrow samples taken to confirm the diagnosis and to help to determine exactly what type of leukaemia a patient has. More specialised tests are often done at the same time. Usually, a chest x-ray will be taken and also scans, to look for swollen lymph nodes, or other affected sites. Blood samples will be taken to test for any problems with the liver, kidneys or other organs. In ALL a sample is taken of the fluid which surrounds the brain and spinal cord – cerebrospinal fluid (CSF). This is because ALL cells can get into the nervous system, which protects them from most kinds of treatment. This is more common in T-ALL. Some blood tests and scans will be repeated to check for the response to treatment and any complications. Other tests are usually only done at diagnosis. Other tests which may be done include:

  • Lumbar puncture – a sample of fluid (CSF) from around the spine – To show whether there are leukaemia cells in the nervous system
  • X-rays, ultrasound or scans (CT or MRI) – To monitor impact on organs of the body

Blood tests, bone marrow samples and lumbar punctures will be repeated throughout treatment to monitor response.


Staging is not used for T-ALL, because it is spread throughout the body when first diagnosed. There is a system to classify T-ALL as high-risk, standard or low-risk. It is important to stress that this refers to the chance of a good response giving standard treatment. If treatment is selected according to risk group, many patients with high-risk disease will do very well. It is also, unfortunately, not always true that a patient with low risk disease will do well. The risk group is only of the factors which affects the outcome of treatment. Most cases of T-ALL are classed as high-risk; with appropriate treatment they have a very good chance of successful treatment.

Treatment of T-ALL

If you are being treated for any type of leukaemia, you may be asked to consider taking part in a clinical trial. Clinical trials are scientific studies to find the best treatment; you can find more information on our website at here. Virtually all patients with T-ALL will start treatment immediately. The main exception would be if a patient is very ill with other medical problems and is not fit enough to receive treatment. Acute leukaemia is often curable with standard treatments, in younger and/or fitter patients. Older or less fit patients will usually have a good initial response to treatment but the condition will most often come back, this is known as a relapse. The main ways in which leukaemia is treated are:

  • Chemotherapy – Cell-killing drugs. Steroids are normally used along with chemotherapy for T-ALL
  • Radiation therapy – Usually only given as part of a stem cell transplant in T-ALL
  • Stem cell transplant – Younger/fitter patients may be given a stem cell transplant (bone marrow transplant). This is done using healthy stem cells from a donor. This is done for T-ALL if chemotherapy does not cure the disease

Chemotherapy is the use of cell-killing drugs. These kill the cancer cells and/or stop them from dividing. Chemotherapy is usually given in blocks or ‘cycles’ of treatment. One cycle of treatment will consist of a series of doses of chemotherapy followed by a break for the healthy cells to recover. After initial treatment is complete lower-dose chemotherapy is continued for two to three years. This is called maintenance therapy. T-ALL cells may be found in the fluid around the brain and spine (called CSF) so chemotherapy for T-ALL includes injections into this fluid. This is called intrathecal chemotherapy. This is more common in T-ALL than in other forms of ALL. Chemotherapy is normally given as a combination of drugs, which, for T-ALL, will almost always include steroids. Steroids used to treat lymphoid leukaemia are a laboratory-made version of chemicals naturally made by the body. They are very different from the type of steroids sometimes misused by body builders or sportsmen. The details of your treatment will vary depending on the specific features of the leukaemia, age and general fitness. Patients will be given a chance to discuss treatment options and detailed information on their treatment plan before it starts. The side effects of treatment vary between different types of treatment and different patients. Patients will be given detailed information about any likely side effects before treatment starts.

Questions to ask your doctor about T-ALL

We understand going through a blood cancer through journey can be difficult. It may help to talk to a close friend or relative about how you are feeling. Here are some questions that may be useful to ask your doctor.

  • How would I know if I had T-ALL?
  • What tests will I need to have?
  • What will the tests show?
  • How long will the results take?
  • How rare is T-ALL?
  • What sort of treatment will I need?
  • How long will my treatment last?
  • What will the side effects be?
  • Is there anything I should or shouldn’t eat?
  • Will I be able to go back to work?
  • Where can I get help with claiming benefits and grants?
  • Where can I get help dealing with my feelings?

Further downloads and support

You can order patient information on T-ALL through our online shop. 

Published: September 2019

Review date: September 2022