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Myelodysplastic/Myeloproliferative Neoplasms


Fatigue, unintended weight loss, discomfort beneath the rib cage and night sweats may be signs of myelodysplastic/myeloproliferative neoplasms, particularly in older patients. It’s a term that encompasses several conditions that may develop when someone has too many white blood cells.

Myelodysplastic/myeloproliferative neoplasms exhibit qualities of two conditions: myelodysplastic syndromes—when too few blood stem cells mature properly in the bone marrow, leading to a shortage of healthy red blood cells, white blood cells or platelets—and myeloproliferative neoplasms, when too many blood stem cells mature into red blood cells, white blood cells, or platelets.

The most commonly diagnosed myelodysplastic/myeloproliferative neoplasm is chronic myelomonocytic leukemia (CMML), which affects about 3 in 1,000,000 people. Juvenile myelomonocytic leukemia (JMML) accounts for 2% of childhood leukemia diagnoses, or 1.2 in 1 million people.

Most people live 1 to 5 years after diagnosis with this condition, although there are exceptions and some live longer. People who also have anemia may have worse outcomes. Those who undergo stem cell transplants may be cured of myelodysplastic/myeloproliferative neoplasms, but the procedure is risky and isn’t appropriate for all people who are diagnosed with these conditions.

What are myelodysplastic/myeloproliferative neoplasms?

Myelodysplastic/myeloproliferative neoplasms are diseases that arise when too many white blood cells are produced in the bone marrow. They include:

  • Chronic myelomonocytic leukemia (CMML)
  • Atypical chronic myelogenous leukemia (aCML)
  • Juvenile myelomonocytic leukemia (JMML)
  • Myelodysplastic/myeloproliferative neoplasms with ringed sideroblasts and thrombocytosis (MDS/MPN-RS-T)
  • Unclassifiable myelodysplastic/myeloproliferative neoplasm (MDS/MPN-U)

CMML is the most commonly diagnosed type of myelodysplastic/myeloproliferative neoplasm. It mainly affects older adults, with males being diagnosed twice as often as females. JMML is diagnosed most frequently in children aged 2 and under, although it may affect children up to age 14. Other myelodysplastic/myeloproliferative neoplasms are quite rare.

In healthy people, the bone marrow produces blood stem cells that turn into “blast” cells, which then develop into different types of blood cells. When someone has a myelodysplastic/myeloproliferative neoplasm, they may produce too many blood cells, or their blasts may not fully develop, which leads to lower levels of blood cells than usual. These problems may cause a variety of symptoms, including an enlarged spleen and a tendency to get sick frequently.

What causes myelodysplastic/myeloproliferative neoplasms?

Doctors don’t know what causes myelodysplastic/myeloproliferative neoplasms in most people. Some cases have been linked to previous cancer treatment, exposure to cancer-causing chemicals or to radiation. In other cases, there are chromosomal abnormalities that are associated with these conditions. The abnormalities are not inherited; rather, they develop at some point in life.

What are the symptoms of myelodysplastic/myeloproliferative neoplasms?

People who have myelodysplastic/myeloproliferative neoplasms may experience symptoms such as:

  • Fatigue
  • Fever
  • Unexplained weight loss
  • More frequent infections
  • Bruising easily
  • Bleeding easily
  • Pain, discomfort or a feeling of fullness below the ribcage
  • Swollen lymph nodes
  • Skin rashes
  • Pale skin
  • Night sweats
  • Signs of small, pinpoint bleeds beneath the skin (petechiae)
  • Enlarged spleen
  • Enlarged liver

What are the risk factors for myelodysplastic/myeloproliferative neoplasms?

Myelodysplastic/myeloproliferative neoplasms typically affect adults in their 70s and beyond, while JMML typically affects toddler-aged children.

Because aCML, MDS/MPN-RS-T and MDS/MPN-U are very uncommon, little is known about additional risk factors for these specific conditions. However, doctors are aware of additional risk factors for CMML and JMML.

Risk factors for CMML include:

  • Being male
  • Previous exposure to radiation
  • Previous chemotherapy treatment
  • Past exposure to certain cancer-causing chemicals

Risk factors for JMML include:

  • Being male
  • Having had neurofibromatosis type 1

How are myelodysplastic/myeloproliferative neoplasms diagnosed?

Doctors may diagnose myelodysplastic/myeloproliferative neoplasms after learning about a patient’s medical history, performing a physical examination and using various diagnostic tests.

When doctors take a medical history, they will want to know if the person has had cancer before and whether they have been exposed to radiation at work or during prior cancer treatments. They will also ask about current symptoms.

During a physical exam, doctors will look for unexplained bruises, swollen lymph nodes, rashes, or pale skin. They may press gently on the abdomen to see if the spleen or liver feels enlarged or tender.

Blood tests are key when diagnosing myelodysplastic/myeloproliferative neoplasms. Doctors will look at the results of a complete blood count test (CBC), which shows the proportion of white blood cells, red blood cells and plasma present in the blood. Other blood tests can rule out infections and conditions that aren’t myelodysplastic/myeloproliferative neoplasms. Testing can also determine which types of white blood cells are present in the blood, and in what proportion.

When doctors suspect a myelodysplastic/myeloproliferative neoplasm, they perform a bone marrow biopsy to check for abnormal cells within the bone marrow. For this brief procedure, doctors numb a small area on the hipbone, then insert a small, hollow needle that removes a tiny piece of bone, along with bone marrow. The tissue is examined under a microscope to see if there are chromosomal changes or mutations that may indicate cancer. The bone marrow is also examined for a higher than usual percentage of blasts. The quantity of blasts present in the bone marrow helps doctors differentiate between a myelodysplastic/myeloproliferative neoplasm or a different type of leukemia.

How are myelodysplastic/myeloproliferative neoplasms treated?

Myelodysplastic/myeloproliferative neoplasms may be difficult to treat. These treatments are available:

  • Chemotherapy. Certain chemotherapy medications may help to minimize symptoms from myelodysplastic/myeloproliferative neoplasms. They may encourage healthy bone marrow cells to grow, allowing for the production of normal blood cells.
    • A drug called hydroxyurea may help to reduce high numbers of white blood cells in someone’s blood, and it may also help to reduce an enlarged spleen.
    • Azacitidine, decitabine and decitabine/cedazuridine are chemotherapy drugs that may destroy cells that are reproducing too rapidly, which may allow health bone marrow cells to grow.
  • Targeted therapy. One drug, imatinib mesylate, may help to treat people with CMML, if part of a chromosome has broken off and attached itself to a different chromosome. This swap of chromosomal information may lead to the formation of a cancer-causing gene. Imatinib mesylate targets the most common mutation that affects chromosomes in people with CMML.
  • Radiation therapy. This treatment may be offered to some people who have extreme discomfort or other side effects caused by an enlarged spleen. Radiation may help to reduce the size of the spleen and minimize or eliminate certain symptoms, but it won’t have a direct effect on myelodysplastic/myeloproliferative neoplasms.
  • Blood transfusions. People with myelodysplastic/myeloproliferative neoplasms often need blood transfusions. Frequent blood transfusions may lead to higher than normal levels of iron in the blood, which may, over time, be harmful to the heart or liver. To counteract this problem when people have had multiple blood transfusions, doctors may prescribe drugs known as chelating agents, which help rid the body of excess iron.
  • Stem cell transplant. A stem cell transplant may stop the bone marrow from producing abnormal blood cells by providing them with new blood-producing cells. First, a healthy donor provides blood stem cells. Then, the person with a myelodysplastic/myeloproliferative neoplasm undergoes chemotherapy and/or radiation therapy to destroy the blood-forming cells in their bone marrow. Afterward, they receive an infusion of stem cells from the healthy donor, which may help them begin to produce healthy blood cells.

Receiving stem cells from a healthy donor may cure some cases of CMML, JMML, aCML and MDS/MPN-U, but the procedure itself may sometimes be fatal. Also, some are not eligible for stem cell transplants, due to advanced age, frailty and other health complications.

What is the outlook for people with myelodysplastic/myeloproliferative neoplasms?

While some individuals with CMML live for 10 or more years after diagnosis, the average survival time is about 3 years.

Children who are diagnosed with JMML may live for 1 to 4 years after diagnosis. Younger children tend to have a better prognosis than older children.

Other myelodysplastic/myeloproliferative neoplasms are diagnosed so infrequently, there aren’t reliable figures about treatment response in patients. However, people with aCML may live for an average of 2 years after diagnosis. Those with MDS/MPN-U may survive for 12 to 22 months after diagnosis.

Only about 10% of people with myelodysplastic/myeloproliferative neoplasms are eligible for stem cell transplants, due to health complications that may prevent them from undergoing and surviving the procedure.

Myelodysplastic/myeloproliferative neoplasms may recur after treatment. Additionally, 15 to 20% of people with CMML may develop acute myeloid leukemia (AML), another form of leukemia, within 2 years of diagnosis. People with JMML, aCML and MDS/MPN-U may also develop AML, which contributes to poor survival rates.

This article was medically reviewed by Amer Zeidan, MBBS.