LGL leukemia is a rare form of blood cancer. It causes a type of white blood cell to mutate and grow out of control. People with slow-growing LGL leukemia may not require treatment for some time.

Doctors do not yet know the cause of LGL leukemia, but autoimmune diseases appear to be a significant risk factor. The median age of diagnosis is 60 years, and less than a quarter of people with the condition are younger than 50.

This article explores LGL leukemia, including its causes, risk factors, symptoms, and treatment. It also describes living with blood cancer.

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LGL leukemia is a rare form of blood cancer. It causes a type of white blood cell, lymphocytes, to grow uncontrollably. They become enlarged and develop granules, which doctors can see when they examine the affected cells under a microscope. These characteristics are what give LGL leukemia its name.

When lymphocytes become cancerous, they grow and divide abnormally. The new cells do not protect the body from infection as they should, and they crowd out healthy blood cells. This causes a range of problems in the body.

LGL leukemia begins in the bone marrow. Eventually, cancerous lymphocytes can enter the bloodstream and spread to other areas of the body. The cancer may grow and spread quickly or slowly.

There are also two subtypes: T-cell LGL (T-LGL) leukemia and natural killer cell LGL leukemia. The symptoms and treatments of both are similar.

There is no cure for LGL leukemia yet.

However, the T-cell subtype can progress slowly. In a 2016 review that included 1,150 people with T-LGL leukemia, researchers found that the median life expectancy after diagnosis was 9 years.

People with natural killer cell LGL leukemia or aggressive T-LGL may have less favorable outcomes. There is less research into the best treatments for these types, and they tend to be more resistant to treatment.

Scientists do not fully understand the causes of LGL leukemia. However, they have found a link between autoimmune diseases and this form of cancer.

According to a 2017 study, approximately 10–40% of people who develop LGL leukemia have a history of autoimmune disorders, particularly rheumatoid arthritis. Researchers have also noticed a link with other autoimmune conditions, such as Sjögren’s disease.

There is also evidence that genetic mutations may be involved in LGL leukemia. Different research from 2017 notes that 30–40% of people with T-LGL leukemia have mutations in the STAT3 gene.

Most people have some symptoms when they receive a diagnosis of LGL leukemia. These symptoms could include:

  • fever
  • night sweats
  • unintentional weight loss
  • recurring infections
  • persistent fatigue
  • anemia, which causes symptoms such as dizziness, weakness, and headaches

Around 25–50% of people also have an enlarged spleen, which doctors call splenomegaly. Rarely, people with LGL leukemia have an enlarged liver or swollen lymph nodes.

Various tests can help a doctor diagnose LGL leukemia. Typically, they perform a blood smear, which involves taking a blood sample to examine under a microscope. This allows them to check for abnormal lymphocytes.

In addition, the doctor may order a complete blood count, which also involves giving a blood sample. The results may show a high white blood cell count and a low neutrophil count.

Next, a test called flow cytometry can determine whether the cancerous cells are T-cells or natural killer cells, indicating the subtype.

To confirm the diagnosis, the doctor may request a bone marrow aspiration or biopsy. This involves taking a sample from inside a bone and examining it under a microscope.

Treatment for LGL leukemia varies, depending on how quickly the disease is progressing. According to the 2016 study, only around 45% of people with LGL leukemia need immediate treatment, though most people require treatment eventually.

If a person has slow-growing LGL leukemia, their medical team may recommend monitoring the symptoms and performing regular blood tests.

The doctor may then decide to begin treatment if:

  • The person’s neutrophil count drops considerably.
  • They develop severe anemia.
  • They have an autoimmune condition that requires treatment.

There is no standard treatment for LGL leukemia. Doctors typically use a combination of chemotherapy and immune-suppressing drugs as a first-line treatment. This may include cyclosporine, cyclophosphamide, or methotrexate.

After the person has taken these medications for several months, their doctor may stop the regimen and perform tests to check the effects of the treatment. If the response to the treatment is good, the person may be able to take methotrexate or cyclosporine indefinitely to control the disease. If not, doctors may try other options, such as:

  • purine analog drugs
  • monoclonal antibody therapy
  • stem cell transplantation
  • surgery to remove the spleen, which is called a splenectomy

A person may be able to access other promising treatments by joining a clinical trial if their doctor believes that they are eligible.

Receiving a diagnosis of LGL leukemia can be extremely difficult. The disease can affect mental health as well as physical health, and the symptoms may have significant effects on daily life.

If someone is having treatment, healthcare professionals can recommend ways to manage any side effects. And even if a person does not need treatment right away, they and their healthcare team can take steps to help.

When possible, it is a good idea to:

  • Attend regular medical appointments: This allows doctors to monitor the condition and address any changes as soon as possible.
  • Make changes to manage fatigue: Fatigue can make the smallest tasks challenging. Pacing oneself, taking frequent breaks, and having naps are important for adapting to lower energy levels. An occupational therapist can help a person make changes to their home or daily routine.
  • Adjust eating and sleeping habits: If unintentional weight loss is a symptom, it may help to eat smaller meals more frequently. If loss of appetite is the cause, it may help to have a distraction while eating. Loose, lightweight clothing made from natural fibers may be more comfortable for people with fever or night sweats.
  • Address mental health: Living with a chronic disease and undergoing cancer treatment can be emotionally draining, and it may contribute to stress, anxiety, and a low mood. Talking about this with a therapist, a cancer support group, or understanding friends and family members may help.
  • Avoid exposure to viruses: It is especially important for people with leukemia to avoid contact with people who have viral illnesses, such as a cold, the flu, or COVID-19. Follow the prevention guidelines from the Centers for Disease Control and Prevention (CDC), and ask others to do the same.

The American Cancer Society provides further information and support services for people living with cancer.

Learn more about home care for people with leukemia.

LGL leukemia is a rare form of blood cancer that causes a type of white blood cell to enlarge and develop granules, which are visible under a microscope. These cells grow and divide quickly, and they cannot protect someone from infections as they should.

Researchers do not understand what causes LGL leukemia, but there appears to be a link with autoimmune diseases, such as rheumatoid arthritis. A cure does not yet exist, but a combination of medications or other treatments can prevent cancerous cells from growing, slowing the course of the disease.

Living with LGL leukemia can be challenging. Whenever possible, seek emotional, psychological, and physical support from understanding family members and friends, support groups, and a medical team.