Myeloproliferative Neoplasms (MPN)

Myeloproliferative neoplasms (MPNs) are a rare, closely related group of blood disorders in which the bone marrow overproduces red blood cells, white blood cells, or platelets. This results in an elevated count of one or multiple types of blood cells. “Myelo” means bone marrow, where the blood cells are made, while “proliferative” refers to the rapid production of cells, and “neoplasm” is an abnormal growth of cells.

There are six types of MPNs, generally defined by the type of cell which is most affected:

• Polycythemia vera — overproduction of red blood cells
• Essential thrombocythemia — overproduction of platelets
• Chronic myeloid leukemia — overproduction of all white blood cells
• Primary myelofibrosis — production of fibrous tissue in the bone marrow
• Chronic neutrophilic leukemia — overproduction of neutrophils, a type of white blood cell
• Chronic eosinophilic leukemia — overproduction of eosinophils, another type of white blood cell

Certain types of MPNs sometimes become acute leukemia, a blood cancer in which too many immature white blood cells are produced.

Many people with MPNs do not have any symptoms; however, a routine blood test may confirm high levels of red blood cells, white blood cells, or platelets. Each type of MPN may cause varying symptoms. More common symptoms include:

• Headaches
• Fatigue and tiredness
• Blurred vision
• Dizziness
• Shortness of breath
• Loss of appetite
• Weight loss
• Night sweats
• Itching
• Raised blood pressure

Other symptoms are specific to the type of MPN.

Although seen across all age groups, MPNs are more often seen in adults. A genetic mutation in a protein that regulates blood cell production — JAK2 — is found in a large number of people with MPNs, while a smaller number have other mutations in other genes, such as MPL or CALR. Nevertheless, the common denominator is that all these mutations activate the JAK2 pathway.

To diagnosis a myeloproliferative neoplasm (MPN), your doctor will complete a physical examination and request a thorough health history.

A series of tests will be performed to confirm the diagnosis, including:

• Complete blood count looking at the total number and type of blood cells in the blood
• Blood smear to examine you or your child’s blood under a microscope
• Bone marrow aspiration and biopsy for a definitive diagnosis
• Cytogenetic analysis to see whether chromosomes are abnormal
• Sequencing analysis of blood or bone marrow for common mutations causing MPNs

MPNs cannot be cured, but there are a number of different ways to manage the type of condition to safeguard short- and long-term health. Low-risk MPNs can be treated with low-dose aspirin along with a phlebotomy to reduce the risk of a blood clot. Higher-risk MPNs will require treatments to manage overactive blood cell production, such as chemotherapy, radiation therapy, stem cell transplant, splenectomy, or targeted therapies.

Clinical trials may offer additional treatment options and promising new treatments or procedures.

Children and teens with MPNs are treated through the Blood Disorders Center at 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, a world leader in the treatment and research of all types of pediatric blood disorders, including MPNs.