Myeloproliferative Disorders or Myeloproliferative Neoplasms (MPNs)

Myeloproliferative neoplasms (MPNs) are also called myeloproliferative disorders or myeloproliferative diseases. They occur when the bone marrow makes too many blood cells. These conditions are different from myelodysplastic syndromes (MDS ), where the bone marrow does not make enough functional blood cells , although with some of these conditions there is some overlap (see below).

What are myeloproliferative disorders?

In MPNs, too many blood stem cells (immature cells) in the bone marrow develop into mature blood cells. These extra cells build up in the blood and bone marrow over time. This condition usually gets worse slowly as the number of blood cells goes up.

There are 3 main types of MPNs:

• Polycythemia vera
• Primary myelofibrosis
• Essential thrombocythemia

Other types of MPNs include:

• Chronic myeloid leukemia (CML)
• Chronic neutrophilic leukemia
• Chronic eosinophilic leukemia

Myelodysplastic/myeloproliferative neoplasms (MDS/MPNs)

MDS/MPNs are rare blood cancers that have features of both myelodysplastic disorders and myeloproliferative neoplasms:

• Myelodysplastic features: The blood stem cells in these conditions don’t mature into healthy red blood cells, white blood cells, or platelets. The immature blood cells (blasts) don’t work the way they should, and they tend to die quickly.
• Myeloproliferative features: Too many blood stem cells become one or more type of blood cell, resulting in too many of these types of cells. The number of these blood cells goes up slowly over time.

The 3 main types of MDS/MPNs are:

• Chronic myelomonocytic leukemia (CMML)
• Juvenile myelomonocytic leukemia (JML)
• Atypical chronic myeloid leukemia (aCML)

Each type affects blood cell production in different ways, and treatment approaches depend on the specific type and symptoms.