Large granular lymphocytic (LGL) leukemia is a kind of cancer that affects blood cells. The disease is rare: Only about 1,000 people per year are diagnosed with it. It affects men and women in roughly equal numbers, and most of those diagnosed are over 60 years old.

Here’s what we know about this form of leukemia.

Your blood is made up of four different parts:

  • plasma, or the liquid part
  • platelets, which cause your blood to clot
  • red blood cells, which carry oxygen to your body parts
  • white blood cells, which fight infection

Some of your white blood cells are larger than the rest. These cells contain tiny granules that can be seen under a microscope.

In people with LGL leukemia, these large, granular white blood cells copy themselves until there are too many. The fact that the white blood cells (also called lymphocytes) replicate themselves is what makes this disorder a type of cancer.

Your blood contains two different types of lymphocytes: T-cells (T-LGL) and B-cells, which are also known as natural killer cells (NK-LGL). B-cells fight off invading bacteria and viruses. T-cells attack other cells in your body that have become harmful, like cancer cells.

When your T-cells are copying themselves too much, you have T-LGL leukemia. If your natural killer cells are replicating too much, you have NK-LGL leukemia.

Most cases of LGL leukemia are chronic and slow-growing, whether they’re NK-LGL or T-LGL. Only around 10 percent of all LGL cases are aggressive, fast-growing cells.

Researchers don’t yet know what causes LGL leukemia. The disorder is associated with a genetic change or mutation, usually to the STAT3 and STAT5b genes.

Between 10 and 40 percent of people with LGL leukemia also have a history of autoimmune disorders. The immune disorder most often associated with LGL leukemia is rheumatoid arthritis (RA).

About 20 percent of those with LGL leukemia also have RA. So far, researchers have been unable to determine which disorder began first.

Most people who are diagnosed with LGL leukemia will experience some of these symptoms:

A healthcare professional may look for other symptoms, too, including:

  • decreased number of platelets in your blood
  • lower numbers of neutrophils (a subtype of white blood cell that’s an immune system “first responder”)
  • enlargement of your liver or spleen

When to schedule a medical appointment

You should contact your doctor and seek treatment if you’re having recurring infections, especially if you have a fever that doesn’t go away or you have other infection symptoms, such as swelling or sores, that aren’t getting better.

Healthline

To find out if you have LGL leukemia, a healthcare professional will analyze a sample of your blood. Your doctor may also take a sample of your bone marrow, often from your hip area, to look for abnormal cells.

To determine which type of LGL leukemia you have, your doctor could use a laser technology called flow cytometry to identify whether T-cells or NK-cells are replicating too much.

Most cases of LGL leukemia are slow growing. Doctors sometimes take a wait-and-watch approach to treatment.

You may not start treatment until tests or symptoms show that the condition has reached a certain level.

If tests show that your neutrophil levels have dropped too much, your doctor may start treatment at that time. Around 45 percent of people with this condition needed immediate treatment.

When treatment for LGL leukemia begins, it may or may not follow the same intensive course as other cancer treatments.

Most people will eventually need some combination of chemotherapy and immune-suppressing drug therapy. Your medications could include:

  • Methotrexate. This drug slows down your body’s immune response and slows the growth of cancer cells.
  • Cyclophosphamide. This chemotherapy drug damages the DNA in cancer cells so that they can’t copy themselves as effectively.
  • Cyclosporine. This drug stops your immune system from attacking your cells
  • Fludarabine. This drug slows the growth of cancer cells.
  • Alemtuzumab. This drug causes your immune system to attack cancer cells.

In some cases, treatment for LGL leukemia involves a bone marrow or stem cell transplant. It’s also possible that your treatment could include removing your spleen, an organ in your abdomen that filters your blood and helps maintain your immune system.

Two to three times a year, you may need to visit a healthcare professional to have bloodwork done to monitor your health and the activity of your white blood cells.

While there’s no cure for LGL leukemia, most cases progress very slowly, unlike other forms of leukemia. One study that followed 1,150 people with the disease found that they lived an average of 9 years after their diagnosis.

The more aggressive form of LGL leukemia doesn’t respond well to treatment. Life expectancy is likely much shorter for those with this very rare subtype of LGL leukemia.

LGL leukemia is a rare type of cancer where large white blood cells copy themselves too much, making your body prone to frequent infections.

Most cases of LGL leukemia are slow-growing, so treatment might not be necessary at first.

Eventually, people with this condition might need a combination of chemotherapy and immunosuppressing medications to slow the growth of cancer cells. There’s no cure yet for LGL leukemia.

A small percentage of cases are a faster-growing type of leukemia that doesn’t respond well to treatments. Life expectancy for this subtype is shorter than the slow-growing type.