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The Sidney Kimmel Comprehensive Cancer Center

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Large Granular Leukemia

Large granular lymphocyte (LGL) leukemia is a rare cancer of white blood cells called lymphocytes, which originate in the lymph system and bone marrow and help fight infection. In people with the disease, the lymphocytes are enlarged and contain granules, which can be seen when the blood is examined under the microscope. There are two types of LGL leukemia: T-cell (T-LGL) and natural killer cell (NK-LGL). Each type may be chronic (slow-growing) or aggressive (fast-growing). LGL leukemia affects both men and women. The average age of diagnosis is 60.

Risk factors

While the exact cause of LGL leukemia is unknown, autoimmune diseases, such as rheumatoid arthritis, are diagnosed before the onset of LGL leukemia in about 20 percent of cases.


Most patients have symptoms at the time of diagnosis, including:

  • Low levels of platelets or infection-fighting neutrophils in the blood
  • Anemia
  • Recurrent infections
  • Fever/night sweats
  • Unintended weight loss
  • Enlargement of the spleen


Doctors can diagnose LGL leukemia by examining blood samples under a microscope and the following tests:

  • Bone marrow exam – Samples of fluid and solid portions of the bone marrow may be removed under local anesthesia, allowing the doctor to look for abnormalities.
  • Flow cytometry – A specialized technique in which different types of blood or bone marrow cells are separated, identified and counted. The test can determine if LGL leukemia cells are T cells or NK cells.


Treatments for LGL leukemia vary based on individual patient’s disease. Some patients initially can be monitored by a physician without starting treatment. Treatments include:

  • Medications – including immunosuppressive drugs like methotrexate; cylophosphamide to treat anemia; and cyclosporine or G-CSF for neutropenia, an abnormally low number of white blood cells.
  • Chemotherapy
  • Surgery to remove the spleen
  • Stem cell transplant/Bone marrow transplant – The only curative treatment for bone marrow failure disorders is stem cell transplantation, in which a patient’s bone marrow/stem cells are replaced with those from a healthy, matching donor. The most successful outcomes are among patients who have an unaffected, tissue-compatible sibling to serve as a donor.

For more information on bone marrow transplants


The Leukemia & Lymphoma Society