Juvenile Myelomonocytic Leukemia

  • Overview

    What is leukemia?

    Leukemia is blood cancer. It develops in the bone marrow—the soft, spongy center of the long bones that produces the three major blood cells:

    • white blood cells (fight infection)
    • red blood cells (carry oxygen)
    • platelets (help blood clot and stop bleeding)

    Normal, healthy cells only reproduce when there is enough space for them to fit, and the body regulates this by sending signals so the cells know when to stop. When your child has leukemia, two things happen:

    1. His bone marrow makes white blood cells that are abnormal.
    2. These abnormal cells do not respond to the signals to stop, and keep reproducing regardless of space available.
    3. The abnormal/immature white cells, called “blasts,” reproduce quickly, and—unlike normal white blood cells—do not help fight infection.
    4. When blasts begin to crowd out the healthy cells in the bone marrow, your child begins to experience symptoms of leukemia (e.g., infections, anemia, bleeding).

    What is chronic juvenile myelomonocytic leukemia (JMML)?

    JMML is, in some ways, similar to chronic myelogenous leukemia (CML), an uncommon leukemia in children. JMML is a leukemia in which the normal bone marrow production of cells becomes very disregulated. A preponderance of immature monoocytes, a type of white blood cell, is produced in the marrow. The marrow continues to produce these abnormal cells, which crowd out other healthy blood cells.

    • JMML generally cause a more severe disruption in blood counts early in the disease than CML, and is not as responsive to treatment.
    • The symptoms associated with JMML can occur over a period of weeks to months.
    • JMML usually affects children under the age of 2 years. It is a very rare form of childhood leukemia.

    Patients with JMML are treated through Dana-Farber/Boston Children's Cancer and Blood Disorders Center, an integrated pediatric hematology and oncology partnership between Dana-Farber Cancer Institute and Boston Children’s Hospital. Visit the Dana-Farber/Boston Children's website for information on our partnership. JMML survivors receive a comprehensive follow-up evaluation from their cancer care team through the David B. Perini, Jr. Quality of Life Clinic at Dana-Farber Cancer Institute.

    • Our childhood cancer survivorship clinic is held weekly.
    • In addition to meeting with your pediatric oncologists, your child may see one of our endocrinologists, cardiologists, neurologists, neuro-psychologists or alternative/complementary therapy specialists.
    • We also offer the following services:
      • patient and family education
      • psychosocial assessment
      • genetic counseling
      • reproductive and fertility evaluation and counseling
      • opportunities to speak with other childhood cancer survivors

  • In-Depth

    How common is leukemia?  Who develops it? 

    Leukemia is the most common form of cancer in childhood.

    • It affects approximately 3,000 children each year in the US, accounting for about 30 percent of childhood cancers.
    • Leukemia can occur at any age, although it is most commonly seen in children between 2 and 6 years of age.
    • The disease occurs slightly more frequently in males than in females, and more commonly seen in Caucasian children than in children of other races.

    What causes JMML?

    In nearly all cases, it is not known what causes leukemia. In the majority of childhood leukemias, gene mutations and chromosome abnormalities in the leukemia cells occur sporadically (by chance). The abnormalities found in leukemia cells are not found in the other cells of the body.

    Can damage to the child’s immune system lead to leukemia?

    Your child’s immune system plays an important role in protecting his body from diseases, and possibly cancer. This means that an alteration or defect in his immune system may increase the risk for developing leukemia.

    Factors such as exposure to certain viruses, environmental factors, chemical exposures and various infections have been associated with damage to the immune system, but none of these factors has been definitively linked as a cause of childhood leukemia.

    What are the different types of leukemia?

    In addition to JMML, there are three main types of leukemia: acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), and chronic myleogenous leukemia.

    How do myelogenous leukemias differ from lymphoblastic leukemia?

    A different type of white blood cell is affected.  In myelogenous leukemias (both CML and AML) it’s the granulocyte; in lymphoblastic leukemia (ALL), it’s another kind called a lymphocyte.  In all cases—CML, AML and ALL—the cells become abnormal, reproduce too quickly, ignore orders to stop, and crowd out healthy blood cells. 

    What’s the difference between CML and AML?

    Acute myelogenous leukemia (AML):

    • may be also called granulocytic, myelocytic, myeloblastic, or myeloid leukemia.
    • It accounts for about 20 percent of the childhood leukemias.
    • With AML, these cells are most commonly found in the bone marrow and blood, but can also appear in the spinal fluid and the skin.
    • Rarely, they can form into solid tumors called chloromas.
    • The symptoms associated with AML usually occur over a short period of days to weeks.

    Chromic myelogenous leukemia (CML):

    • Symptoms may come on slowly, over weeks or months.
    • CML is often accompanied by a specific type of chromosome rearrangement:
      • Part of chromosome #9 breaks off and attaches itself to chromosome #22.
      • There is an exchange of genetic material between these two chromosomes.
      • This rearrangement changes the position and functions of certain genes, which results in uncontrolled cell growth.

    What are the symptoms of JMML?

    With JMML, there are usually no symptoms in the early stages. When then do occur, your child may experience symptoms over a period of weeks or months.

    Because leukemia is cancer of the blood-forming bone marrow, the initial symptoms are often related to abnormal bone marrow function. The bone marrow is responsible for storing and producing about 95 percent of the body's blood cells, including the red blood cells, white blood cells, and platelets.  While each child may experience symptoms of JMML differently, some of the most common include:

    • general fatigue or weakness
    • recurrent infections- Although there may be an unusually high number of white blood cells on your child’s blood count, these white blood cells are immature and do not fight infection. Your child may have had several viral or bacterial infections over the past few weeks, and may show symptoms of an infection such as fever, runny nose and cough.
    • bone and joint pain– Your child may also experience pain in his bones and joints. This pain is usually a result of the bone marrow being overcrowded and "full."
    • abdominal pain– stomach aches may also be a symptom of leukemia. Leukemia cells can collect in your child’s kidney, liver and the spleen, causing enlargement of these organs. Pain in the abdomen may cause your child lose his appetite, and lose weight.  
    • swollen lymph nodes- your child may also have swelling in the lymph nodes under the arms, in the groin, chest and in the neck. Leukemia cells may collect in the nodes, causing swelling.

    It is important to understand that the symptoms of leukemia may resemble other blood disorders or medical problems. These are common symptoms of the disease, but do not include all possible symptoms. Always consult your child's physician for a diagnosis.

  • Tests

    How is JMML diagnosed?

    In addition to a complete medical history and physical examination, some diagnostic tests may include:

    • bone marrow aspiration and biopsy - Marrow may be removed by aspiration or a needle biopsy under local anesthesia. In aspiration biopsy, a fluid specimen is removed from the bone marrow. In a needle biopsy, marrow cells (not fluid) are removed. These methods are often used together.
    • lymph node biopsy - surgical removal of lymph node tissue to examine under a microscope to look for the presence of cancer cells
    • chromosomal analysis - additional tests that can help distinguish JMML from other leukemias and help physicians tailor treatment to the specific disease
    • complete blood count (CBC) - a measurement of size, number, and maturity of different blood cells in a specific volume of  your child’s blood
    • additional blood tests - may include blood chemistries, evaluation of liver and kidney functions and genetic studies
    • spinal tap/lumbar puncture - A special needle is placed into the lower back, into the spinal canal. This is the area around the spinal cord. The pressure in your child’s spinal canal and brain can then be measured. A small amount of cerebral spinal fluid (called CSF—the fluid that bathes your child’s brain and spinal cord) can be removed tested for infection or other problems.
  • What is the treatment for JMML?

    Specific treatment for JMML will be determined by your child's physician based on:

    • your child's age, overall health and medical history
    • the extent of the disease
    • your child's tolerance for certain medications, procedures or therapies
    • how your child's physician expects the disease to progress
    • your opinion or preference

    Treatment components may include the following (alone or in combination):


    Chemotherapy is a drug treatment that works by interfering with the cancer cell's ability to grow or reproduce.  For JMML, chemotherapy is not generally a successful treatment; however, it may be used to keep the leukemia under control while your child is prepared for a stem cell transplant.

    How is chemotherapy given?

    Different chemotherapies may be given:

    • as a pill to swallow
    • as an injection into the muscle or fat tissue
    • intravenously (directly to the bloodstream, also called IV)
    • intrathecally (directly into the spinal column with a needle)

    How is chemotherapy used?

    This depends on many factors.  Some things to keep in mind:

    • A number of combinations of chemotherapy drugs are currently being used to stabilize, and in some cases, shrink the size of the tumor.
    • Depending on the type of cancer, chemotherapy drugs may be given in a specific order.
    • Chemotherapy may be used alone for some types of cancer, or in conjunction with other therapy such as radiation or surgery.

    Does chemotherapy come with bad side effects?

    While chemotherapy can be quite effective, the drugs do not differentiate normal healthy cells from cancer cells. Because of this, there can be many adverse side effects during treatment. Being able to anticipate these side effects can help your child, family and your child's health care team prepare for and sometimes prevent these symptoms from occurring.

    Stem cell transplant

    Stem cell transplantation offers the best option for overcoming JMML. Stem cells are a specific type of cell from which all blood cells develop. They can develop into red blood cells to carry oxygen, white blood cells to fight disease and infection, and platelets to aid in blood clotting. Stem cells are found primarily in the bone marrow, but some also circulate in the blood stream.

    When your child's stem cells are replaced with those of a healthy and compatible donor, it is called allogeneic transplantation: 

    1. Treatment may begin with high-dose chemotherapy (perhaps combined with radiation therapy) to destroy all of the bone marrow, stem cells and cancerous cells, in your child's body.
    2. Then, healthy stem cells from another person (whose tissue must be the same, or almost the same as your child's) are used to help restore your child's normal blood production.

    Biological therapy

    Biological therapy refers to a wide range of substances that may be able to involve the body's own immune system to fight cancer or lessen harmful side effects of some treatments.

    Other medications

    Other medications may be given to prevent or treat damage to other systems of your child's body caused by leukemia treatment; or for nausea and side effects of treatment.

    Blood transfusions

    A blood transfusion could replace or supplement your child's red blood cells and platelets.


    Your child may be given antibiotics may be given to prevent or treat infections.

    Continuous follow-up care

    Your child's health will be closely monitored to determine response to treatment, detect recurrent disease and manage late effects of treatment.

    What are the various stages of JMML?

    JMML does not have the three phases (chronic phase, accelerated phase and blast crisis) that are common in CML.

    What is the long-term outlook for a child with JMML?

    Your child's prognosis greatly depends on:

    • the extent of the disease
    • his age and overall health
    • his tolerance of specific medications, procedures or therapies
    • new developments in treatment

    Relapse can occur during any stage of treatment, even with aggressive therapy, or may occur months or years after treatment has ended.

    As with any cancer, prognosis and long-term survival can vary greatly. Prompt medical attention and aggressive therapy are important for the best prognosis, and continuous follow-up care is essential. New methods are continually being discovered to improve treatment and decrease side effects of the treatment for the disease.

  • Research & Innovation

    What is the latest research on JMML?

    A variety of chemotherapeutic regimens have been evaluated in the treatment of newly diagnosed high-grade gliomas.

    • While studies in adults have suggested that procarbazine, vincristine and CCNU (PVC) produce modest responses in grade III gliomas, this has not been demonstrated for pediatric cases or for grade IV tumors.
    • Several other regimens have also produced responses, but none has improved survival.
    • Increased doses of chemotherapy in the setting of autologous bone marrow transplant have also not produced notable advantage.

    In the area of stem cell transplantation, the Dana-Farber/Children's Transplant Program is one of only eight institutions around the country that are investigating the use of umbilical cord transplantation.

    Also under study is a novel method for preventing graft versus host disease, a serious complication that occurs when transplanted cells do not recognize the tissues and organs of the recipient's body and react against the recipient's tissue. The result of this treatment approach, if it continues to be as successful, will be that the degree of match between donor and the recipient will not need to be particularly close, greatly increasing the pool of potential donors for each patient. This could also eliminate the need for long-term drug therapy traditionally needed to treat graft versus host disease.

    Dana-Farber Cancer Institute and Children's Hospital are part of the Children's Oncology Group, a national group of pediatric oncologists who work together to carry out clinical trials in pediatric oncology patients.

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