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What is chronic myelomonocytic leukemia (CMML)?

CMML is a rare type of blood cancer that develops from monocytes, which are white blood cells that help fight infections. In CMML, the body makes high levels of immature, abnormal monocytes that don't work correctly and crowd out healthy blood cells.

About 1,100 people are Show Full Answer

What is chronic myelomonocytic leukemia (CMML)?

CMML is a rare type of blood cancer that develops from monocytes, which are white blood cells that help fight infections. In CMML, the body makes high levels of immature, abnormal monocytes that don't work correctly and crowd out healthy blood cells.

About 1,100 people are diagnosed with CMML each year in the United States. It's more common in older adults — about 90 percent of people diagnosed are at least 60 years old. Men are twice as likely to develop CMML as women.

CMML is related to both myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPNs), sharing characteristics of both conditions. It's considered a separate category that overlaps these two groups. CMML has three main subtypes based on blast cell levels:

- Type 0: Fewer than 2% blasts in blood and less than 5% in bone marrow
- Type 1: 2-4% blasts in blood or 5-9% in bone marrow
- Type 2: 5-19% blasts in blood and 10-19% in bone marrow

CMML can also be categorized as myelodysplastic (MD-CMML) or myeloproliferative (MP-CMML). About half of people have the MP subtype, which involves high white blood cell counts. Symptoms vary by subtype. MD-CMML symptoms include:

- Weakness or tiredness
- Tiny red spots in the skin (petechiae)
- Easy bruising and bleeding problems
- Frequent infections

MP-CMML symptoms include:

- Enlarged spleen or liver
- Feeling full quickly
- Night sweats
- Bone pain
- Weight loss

If you notice these symptoms, talk with your doctor, as they're more commonly caused by other conditions. The prognosis varies by type. About 20% of people with type 0 or 1 CMML live five years or more after diagnosis, while about 10% with type 2 survive five years or more.

About 15-30% of people with CMML later develop acute myeloid leukemia (AML). The risk is higher with type 2 CMML — about 63% develop AML within five years, compared to 18% with type 0 or 1.

 AI-generated responses are not a substitute for medical advice. These services are not intended to diagnose, treat, or cure any condition or disease. Always ask your doctor about specific health concerns.

Chronic Myelomonocytic Leukemia: An Overview