T-cell prolymphocytic leukaemia (T-PLL): symptoms, tests and treatment

T-cell prolymphocytic leukaemia (T-PLL) is a rare blood cancer that starts in white blood cells called T cells. T cells are part of the immune system and help the body recognise and fight infection. Leukaemia Care explains that in T-PLL they become abnormal and divide uncontrollably, building up in the bone marrow, lymph nodes and bloodstream.

Blood Cancer UK describes the abnormal cells as prolymphocytes, large immature lymphocytes that are not ready to fight infection properly. As they grow out of control they stop the body producing other blood cells, such as red blood cells, which carry oxygen, and platelets, which help the blood clot.

Leukaemia Care says nobody knows the exact cause. People with T-PLL have genetic changes in their leukaemia cells that make the cells grow out of control, and it is not because of anything the person has or has not done.

T-PLL is very rare, with around 70 diagnoses a year in the UK. That is why many people, and some health professionals, may not have met it before. Leukaemia Care says it is more common in people over 60 and in those with a genetic condition called ataxia telangiectasia, who may develop it at a younger age.

Some people have no symptoms at diagnosis and the disease is found after a blood test for another reason. Symptoms vary and, according to Leukaemia Care and Blood Cancer UK, can include the following.

• Tummy pain, bloating or discomfort from a swollen spleen or liver.

• Feeling tired, breathless or dizzy and looking pale because of a low red blood cell count (anaemia).

• Bruising or bleeding easily, for example nosebleeds or bleeding gums, because of low platelets.

• Swollen lymph nodes, most easily felt in the neck, armpits or groin.

• Skin lesions or a reddish rash, which may look different on black or brown skin.

• Fever, night sweats and weight loss without trying.

• Swelling around the eyes or in the legs or tummy area from fluid build-up, and sometimes breathlessness or chest pain from fluid around the lungs.

Leukaemia Care says diagnosis uses blood tests and sometimes bone marrow tests. Blood tests count red cells, white cells and platelets, where high levels of abnormal T cells are expected with T-PLL and healthy cells may be low, and look at the cells under a microscope. Liver and kidney function and any infections that could flare during treatment are also checked.

A bone marrow sample, usually taken from the back of the pelvis under local anaesthetic, may be done to confirm the diagnosis although it may not always be needed. Samples go for specialist laboratory tests that look at proteins on the surface of the leukaemia cells and genetic changes, and results can take a few weeks. Blood Cancer UK adds that a doctor will examine for swollen nodes, liver and spleen, and that you are likely to have an X-ray or CT scan and possibly a lymph node, bone marrow or skin biopsy.

Leukaemia Care explains that because T-PLL is so rare, it is difficult to run trials, so there are no definite treatment guidelines and different doctors might use different approaches. Your haematology team bases its advice on your symptoms and test results, age and fitness, other medical conditions and your preferences.

If the disease is slow-growing and is not causing symptoms, you may have active monitoring, with regular check-ups and blood tests. Leukaemia Care says there is no evidence that early treatment of T-PLL improves outcomes, so there is no benefit in starting treatment before it is needed, which spares you side effects for longer. You are likely to start treatment if abnormal T cells rise rapidly, healthy blood counts fall, symptoms develop or worsen, the liver, spleen or lymph nodes swell quickly, or the leukaemia affects other parts of the body.

Blood Cancer UK names alemtuzumab, a monoclonal antibody given through a drip, as the standard treatment. If you go into remission after alemtuzumab, a stem cell transplant may be offered, either from a matched donor or using your own cells. It is a very intensive treatment and you need to be generally quite fit. Leukaemia Care also lists chemotherapy and clinical trials among the options your team might consider.

Blood Cancer UK says T-PLL affects the white cells that normally help fight infection, and treatment weakens defences further, so infections may last longer and be more serious than usual, even during active monitoring. Your hospital team may give protective medicines, such as antibiotics, or aciclovir to prevent shingles.

If T-PLL returns after first treatment, alemtuzumab may be offered again if it worked well the first time, or combined with a chemotherapy drug such as pentostatin. If that does not work, your doctor may look for a clinical trial, although there are few in the UK. Palliative care may be offered when there are no more treatment options to manage symptoms and keep you comfortable. Blood Cancer UK describes T-PLL as usually fast growing and says your hospital team are the best people to ask about prognosis.

T-PLL is diagnosed and treated by NHS haematology teams, often in a specialist centre because of its rarity. Private care exists, but the rarity of the condition makes access to experienced haematologists, specialist laboratory testing and trials the main consideration. Ask any clinician involved how they will coordinate with your NHS haematology team.