Chronic Neutrophilic Leukemia

Chronic neutrophilic leukemia (CNL) is a very rare myeloproliferative neoplasm (MPN) classified by an overproduction of neutrophils in the bone marrow. Neutrophils are the most common types of white blood cells in the body and protect the immune system. If the body is fighting an infection, it will produce more neutrophils to attack the infection, but in CNL, the bone marrow makes too high of a number even when they are not needed.

CNL is often associated with mutation of the CSF3R protein. Normally, this protein promotes the production of neutrophils, but in CNL, the mutation causes too many neutrophils to be made. CNL is more commonly seen in older adults. Although uncommon, a family history of CNL may be linked to increased risk of CNL.

When CNL is in an early stage, there may be no symptoms. More aggressive disease may present with symptoms such as pain in the belly, night sweats, fatigue, headaches, night sweats, painful joints, or itching. A routine blood test may show an abnormal number of neutrophils, which can lead to a CNL diagnosis. Your doctor will also perform other blood tests including a bone marrow biopsy to confirm CNL as opposed to another MPN or type of leukemia.

Treatment options for CNL vary based on symptoms, disease characteristics, and personal history. Treatments are individualized. If the disease is in the early stages and you don’t have symptoms, it’s possible that treatment may not be needed right away. Your doctor will monitor the disease for progression or symptom development. CNL does have the ability to transform into a more aggressive type of blood cancer, such as acute leukemia. If you are experiencing symptoms, various treatments are used to help prevent your bone marrow from making too many neutrophils or to kill the cancer cells.

Because CNL is a rare disease, routine follow-ups and blood tests are important in order to monitor and manage the disease.


Richard T. Silver MD Myeloproliferative Neoplasms Center 525 East 70th St., Starr Pavillion, 3rd Floor New York, NY 10021