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Overview of Myeloproliferative Neoplasms


Jane Liesveld

, MD, James P. Wilmot Cancer Institute, University of Rochester Medical Center

Last full review/revision Sep 2020| Content last modified Sep 2020
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In myeloproliferative neoplasms (myelo = bone marrow; proliferative = rapid multiplication; and neoplasm = new abnormal growth), the blood-producing cells in the bone marrow (precursor cells, also called stem cells) develop and reproduce excessively or are crowded out by an overgrowth of fibrous tissue. Sometimes, blood-producing cells appear and reproduce in the spleen and liver. Myeloproliferative neoplasms are caused by genetic mutations. Typically the mutations are acquired and not inherited, although rarely there are families in which several members have these disorders.

The myeloproliferative neoplasms include

In a small number of people, the myeloproliferative neoplasm progresses or transforms to acute leukemia.

Less common myeloproliferative neoplasms include the hypereosinophilic syndromes and chronic neutrophilic leukemia. There are also rare myeloproliferative neoplasms that overlap with myelodysplastic syndrome.

Each myeloproliferative neoplasm is identified according to its predominant bone marrow and blood characteristics. Each disorder has a somewhat typical set of examination findings, test results, and expected course; however, there may be some overlap of features among these disorders because they share the same genetic mutations.

The number of blood-producing cells in the bone marrow can also increase as a reaction to another underlying disorder. For example, lack of oxygen can cause the red blood cells to increase, a serious infection can cause the white blood cells to increase, and inflammation can cause the platelets to increase. In these cases, an increased number of cells in the bone marrow is not considered a myeloproliferative neoplasm but rather a benign reaction. Treating the underlying disorder restores the number of blood cells being produced to normal.


Major Myeloproliferative Neoplasms


Bone Marrow Characteristics

Blood Characteristics

Increased number of mature and immature white cells

Increased number of a certain type of white blood cell (granulocytes)

Sometimes increased number of platelets

Increased number of cells that produce the circulating blood cells

Increased number of red blood cells

Usually, increased number of platelets, white blood cells, or both

Excess fibrous tissue replacing blood-producing cells

Decreased number of red blood cells (anemia) and an increased number of white blood cells

Misshapen red blood cells

The numbers of white blood cells and platelets often eventually decrease, but in some people they increase

Increased number of cells that produce platelets (megakaryocytes)

Increased number of platelets

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