Juvenile myelomonocytic leukemia (JMML) is a rare childhood cancer.
It happens when immature blood cells (called blasts) make too many myelocytes and
monocytes (two types of white blood cells). These myelocytes, monocytes, and blasts
crowd the normal cells in the bone marrow and other organs in the body, causing the
symptoms of JMML.
Who Gets Juvenile Myelomonocytic Leukemia?
Juvenile myelomonocytic (mye-eh-low-mah-nuh-SIT-ik) leukemia usually happens in
children younger than 4 years old.
What Are the Signs & Symptoms of Juvenile Myelomonocytic Leukemia?
JMML develops over time. A child may have very few symptoms at first because they
can take months to develop.
A child with juvenile myelomonocytic leukemia might:
develop anemia, which is
when the bone marrow doesn't make enough red blood cells
get infections often (such as or tonsillitis)
because the white blood cells don't fight germs as usual
feel tired and weak because of anemia and infections
have swollen lymph nodes from collected cancer cells
How Is Juvenile Myelomonocytic Leukemia Diagnosed?
Doctors use special tests when they suspect leukemia.
Blood tests. Tests such as a complete
blood count, liver and
kidney function panels, and blood chemistries can give important information about
the number of normal blood cells and how well the organs are working. The shapes and
sizes of the blood cells are checked with a microscope.
Imaging studies. These may include an X-ray, CT scan, MRI,
or ultrasound. These can see whether there's a mass of leukemia cells in the chest
that could affect breathing or blood circulation. They also can rule out other possible
causes of a child's symptoms.
Bone marrow aspiration
and biopsy. The doctor puts a needle into a large bone, usually the hip,
and removes a small amount of bone marrow. Then the lab does these tests on the bone
Flow cytometry tests. Doctors look at the cancer cells and figure
out the type of leukemia. This is important because treatment differs depending on
By looking at the blood or bone marrow, doctors check for changes in the genes. The
changes can help doctors figure out the best treatment.
tap (lumbar puncture). The doctor uses a small hollow needle to
remove a tiny amount of cerebrospinal fluid (the fluid surrounding the brain and spinal
cord) for exam in a lab.
Tissue typing or HLA (human leukocyte antigen) typing. If a child
needs a stem cell transplant (bone marrow transplant), this test helps doctors find
a suitable stem cell donor. It works by comparing the proteins on the surface of a
child's blood cells with the proteins on a potential donor's cells. The more HLA markers
a child and donor share, the greater the chances that a transplant will be successful.
How Is Juvenile Myelomonocytic Leukemia Treated?
Chemotherapy (the use of drugs to kill cancer cells) may be used to temporarily
control juvenile myelomonocytic leukemia.
Give high-dose chemotherapy
to destroy cancer cells and normal bone marrow and immune system cells.
Put healthy donor stem cells into the body. The new stem cells can rebuild a healthy
blood supply and immune system.
Researchers are looking into the use of alternative treatments, such as:
Molecular-targeted therapies: These medicines slow the growth of cancer cells
by blocking certain molecules or proteins that help cancer cells grow.
medicines mark cancer cells so that the body's immune system can find them and remove
them from the body.
What Else Should I Know?
Having a child being treated for cancer can be stressful for any family. But you're
not alone. To find support,
talk to your doctor or a hospital social worker. Many resources are available to help
you get through this difficult time. You also can find information and support online