Understanding Chronic Myeloproliferative Neoplasms
Good communication between you and your healthcare team is key to understanding your diagnosis and treatment plan.
Myeloproliferative neoplasms are a group of diseases in which the bone marrow makes too many red blood cells, white blood cells, or platelets.
Normally, the bone marrow makes blood stem cells (immature cells) that become mature blood cells over time.
A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. A lymphoid stem cell becomes a white blood cell. A myeloid stem cell becomes one of three types of mature blood cells:
- Red blood cells that carry oxygen and other substances to all tissues of the body.
- Granulocytes, which are white blood cells that help fight infection and disease.
- Platelets that form blood clots to stop bleeding.
There are 6 types of chronic myeloproliferartive neoplasms.
In myeloproliferative neoplasms, too many blood stem cells become one or more types of blood cells. The neoplasms usually get worse slowly as the number of extra blood cells increases.
There are six types of chronic myeloproliferative neoplasms. The type of myeloproliferative neoplasm is based on whether too many red blood cells, white blood cells, or platelets are being made. Sometimes the body will make too many of more than one type of blood cell, but usually one type of blood cell is affected more than the others are. Chronic myeloproliferative neoplasms include the following six types:
Chronic myelogenous leukemia is a disease in which too many white blood cells are made in the bone marrow.
Polycythemia vera is a disease in which too many red blood cells are made in the bone marrow.
In polycythemia vera, the blood becomes thickened with too many red blood cells. The number of white blood cells and platelets may also increase. These extra blood cells may collect in the spleen and cause it to swell. The increased number of red blood cells, white blood cells, or platelets in the blood can cause bleeding problems and make clots form in blood vessels. This can increase the risk of stroke or heart attack. In people who are older than 65 or who have a history of blood clots, the risk of stroke or heart attack is higher. These people also have an increased risk of acute myeloid leukemia or primary myelofibrosis.
Primary myelofibrosis (also called chronic idiopathic myelofibrosis) is a disease in which abnormal blood cells and fibers build up inside the bone marrow.
Myeloproliferative neoplasms are a group of diseases in which the bone marrow makes too many red blood cells, white blood cells, or platelets.
The bone marrow is made of tissues that make blood cells (red blood cells, white blood cells, and platelets) and a web of fibers that support the blood-forming tissues. In primary myelofibrosis, large numbers of blood stem cells become blood cells that do not mature properly (blasts). The web of fibers inside the bone marrow also becomes very thick (like scar tissue) and slows the blood-forming tissue’s ability to make blood cells. This causes the blood-forming tissues to make fewer and fewer blood cells. In order to make up for the low number of blood cells made in the bone marrow, the liver and spleen begin to make the blood cells.
Essential thrombocythemia is a disease in which too many platelets are made in the bone marrow.
Essential thrombocythemia causes an abnormal increase in the number of platelets made in the blood and bone marrow.
Chronic neutrophilic leukemia is a disease in which too many blood stem cells become a type of white blood cell called neutrophils. Neutrophils are infection-fighting blood cells that surround and destroy dead cells and foreign substances (such as bacteria). The spleen and liver may swell because of the extra neutrophils. Chronic neutrophilic leukemia may stay the same or it may progress quickly to acute leukemia.
Chronic eosinophilic leukemia is a disease in which too many white blood cells (eosinophils) are made in the bone marrow.
Eosinophils are white blood cells that react to allergens (substances that cause an allergic response) and help fight infections caused by certain parasites. In chronic eosinophilic leukemia, there are too many eosinophils in the blood, bone marrow, and other tissues. Chronic eosinophilic leukemia may stay the same for many years or it may progress quickly to acute leukemia.
Chronic myeloproliferative neoplasms sometimes become acute leukemia, in which too many abnormal white blood cells are made.Tests that examine the blood and bone marrow are used to diagnose chronic myeloproliferative neoplasms. Treatment for these neoplasms is based on many factors, including which type of chronic meyelofibrosis neoplasm you have.
Source: National Cancer Institute, cancer.gov
This article was published in Coping® with Cancer magazine, Spring/Summer 2023.
