Myelodysplastic/myeloproliferative neoplasms

Myelodysplastic/myeloproliferative Neoplasms at a Glance

• Myelodysplastic/myeloproliferative neoplasms are a group of diseases in which the bone marrow makes too many white blood cells.
• Risk factors and symptoms vary for each type of these neoplasms (see below).
• Different types of treatments are available for patients with myelodysplastic /myeloproliferative neoplasms.
• Some treatments are standard (the currently used treatment), and some are being tested in clinical trials.

What are myelodysplastic/myeloproliferative neoplasms?
Myelodysplastic /myeloproliferative neoplasms are diseases of the blood and bone marrow. 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. The lymphoid stem cell develops into a white blood cell. The myeloid stem cell develops into one of three types of mature blood cells; red blood cells, white blood cells or platelets.

Myelodysplastic/myeloproliferative neoplasms have features of both myelodysplastic syndromes and myeloproliferative disorders.

• 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 develop into one or more types of blood cells and the total number of blood cells slowly increases.

Types of Myelodysplastic/myeloproliferative Neoplasms

The 3 main types of myelodysplastic/myeloproliferative neoplasms include the following:

• Chronic myelomonocytic leukemia (CMML).
• Juvenile myelomonocytic leukemia (JMML).
• Atypical chronic myelogenous leukemia (aCML).

When a myelodysplastic/myeloproliferative neoplasm does not match any of these types, it is called myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN-UC).

Diagnosis

The following tests and procedures may be used to diagnose myelodysplastic/myeloproliferative neoplasms:

• Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease such as an enlarged spleen and liver. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Complete blood count (CBC) with differential: A procedure in which a sample of blood is drawn and checked for the following:
• The number of red blood cells and platelets.
• The number and type of white blood cells.
• The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
• The portion of the sample made up of red blood cells.
• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that produces it.
• Peripheral blood smear: A procedure in which a sample of blood is checked for the presence of blast cells, number and kinds of white blood cells, the number of platelets, and changes in the shape of blood cells.
• Cytogenetic analysis: A test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes. The cancer cells in myelodysplastic/myeloproliferative neoplasms do not contain the Philadelphia chromosome that is present in chronic myelogenous leukemia.
• Bone marrow aspiration and biopsy: The removal of a small piece of bone and bone marrow by inserting a needle into the hipbone or breastbone. A pathologist views both the bone and bone marrow samples under a microscope to look for abnormal cells.