Myeloproliferative Disorders/Neoplasms

Myeloproliferative disorders (MPDs), or myeloproliferative neoplasms (MPNs), are characterized by chronic increases in some or all of the blood cells. MPNs are caused by a change to the DNA of a single stem cell in the marrow, where the blood cells are made.

MPNs include the following types of disorders: Chronic Myelomonocytic Leukemia, Essential Thrombocythemia, Primary Myelofibrosis, and Polycythemia Vera.

Chronic Myelomonocytic Leukemia1

Chronic Myelomonocytic Leukemia (CMML) is a condition in which the body increases its production of monocytes (a type of white blood cell) and has difficulty producing normal numbers of other types of blood cells. People with this disease often have symptoms of anemia — fatigue, headache, pallor — and may develop abdominal pain due to enlargement of the spleen. Some have a low white blood count or a low platelet count and therefore are susceptible to infections or bleeding problems.

Essential Thrombocythemia1

Essential Thrombocythemia is a disease that results in the overproduction of platelets by the bone marrow. (Elevated numbers of platelets can also occur as a result of infection, iron deficiency, and other secondary causes.) Platelets, also known as thrombocytes, prevent bleeding or cause it to stop. High numbers of platelets can result in increased blood clotting or sometimes increased bleeding. Symptoms may include headache, dizziness, tingling in the fingers and toes, bleeding, and enlargement of the spleen. Physicians usually perform a bone marrow biopsy to confirm the diagnosis.

Primary Myelofibrosis1

Primary Myelofibrosis is a disorder in which fibroblasts produce too much fibrous or scar tissue within the bone marrow space. When this happens, blood producing cells are produced in fewer numbers and can be destroyed more rapidly, resulting in anemia, low platelet count, and a tendency to develop infections. The disease often produces few symptoms initially, but may include fatigue and weakness and abdominal pain from an enlarged spleen. Myelofibrosis can occur by itself or in association with Myeloproliferative diseases such as Essential Thrombocythemia and Polycythemia, or in patients with Myelodysplastic Syndromes or Acute Myeloid Leukemia.

Polycythemia Vera1

Polycythemia Vera, a disease of the hematopoietic stem cells (cells that give rise to blood cells), is characterized by the overproduction of red blood cells by the bone marrow. This overproduction can lead to thickening of the blood, which can impair the function of the heart or the brain. Symptoms include headache, shortness of breathe, bleeding, or dizziness. Polycythemia Vera can also increase the likelihood of developing blood clots. To arrive at an accurate diagnosis, physicians must eliminate from consideration other conditions that mimic Polycythemia Vera.

1Memorial Sloan Kettering Cancer Center (2001, January 15). Unknown Myeloproliferative Disorders Retrieved July 9, 2008, from