Myelodysplastic/myeloproliferative neoplasms are a group of diseases in which the bone marrow makes too many white blood cells.
Myelodysplastic /myeloproliferative neoplasms are diseases of the blood and bone marrow.
Anatomy of the bone. The bone is made up of compact bone, spongy bone, and bone marrow. Compact bone makes up the outer layer of the bone. Spongy bone is found mostly at the ends of bones and contains red marrow. Bone marrow is found in the center of most bones and has many blood vessels. There are two types of bone marrow: red and yellow. Red marrow contains blood stem cells that can become red blood cells, white blood cells, or platelets. Yellow marrow is made mostly of fat.
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.
- White blood cells that fight infection and disease.
- Platelets that form blood clots to stop bleeding.
Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.
Myelodysplastic/myeloproliferative neoplasms have features of both myelodysplastic syndromes and myeloproliferative neoplasms.
In myelodysplastic diseases, the blood stem cells do not mature into healthy red blood cells, white blood cells, or platelets. The immature blood cells, called blasts, do not work the way they should and die in the bone marrow or soon after they enter the blood. As a result, there are fewer healthy red blood cells, white blood cells, and platelets.
In myeloproliferative diseases, a greater than normal number of blood stem cells become one or more types of blood cells and the total number of blood cells slowly increases.
This summary is about neoplasms that have features of both myelodysplastic and myeloproliferative diseases. See the following PDQ summaries for more information about related diseases:
- Myelodysplastic Syndromes Treatment
- Chronic Myeloproliferative Neoplasms Treatment
- Chronic Myelogenous Leukemia Treatment