Myelofibrosis

Definition

Myelofibrosis is a rare blood disorder of people over the age of 50.

Description

Myelofibrosis behaves like a leukemia and sometimes turns into one. However, instead of being a disease of white blood cells, it affects a more primordial cell type. Called progenitor cells, these cells retain their ability to become many different types of mature cells and tissues. In myelofibrosis, a progenitor cell begins to produce both immature blood cells and excess scar tissue. The scar tissue is mostly in the bone marrow, which hinders the production of normal blood cells. Extra blood cell production occurs all over the body, but it is most obvious in the spleen. As a consequence, the spleen can grow to an enormous size.

Causes & symptoms

The cause of myelofibrosis is unknown. Most patients are over 50 years old, but it can strike at any age. Symptoms may not appear for a year or more. A enlarged spleen discovered at an annual medical examination may be the first clue. Eventually, symptoms become prevalent.

• Anemia causes fatigue.
• An enlarged spleen can compromise digestion and lead to serious weight loss.
• Exuberant disease activity can hinder lung, bowel, kidney, heart, brain, and spinal cord function.
• General symptoms like fever and sweating are present.

Diagnosis

Since symptoms are similar to other diseases (mostly leukemias), myelofibrosis is not easy to diagnose. Correct diagnosis is imperative because the treatment of each type of disease is quite different. Blood tests and bone marrow biopsies are necessary, but more extensive testing may be required.

Treatment

There is no specific treatment for this disease, but there are many supportive measures that can be taken.

• Anemia is common and can be treated with androgens (male hormones, anabolic steroids). Hematinics may help briefly, but transfusions are required throughout the course of the disease.
• Bone marrow transplantation is also used to treat the anemia.
• Cancer chemotherapy and interferon-alpha have been used.
• Infections in the lung and other organs require antibiotics.
• Radiation or removal of an enlarged spleen is often helpful. A big spleen not only impairs digestion, parts of it can die (infarct) and hurt. It also destroys too many blood cells and causes anemia.
• Radiation may also help localized bone pain, tumors in certain places such as next to the spinal cord, and weeping fluid inside the abdomen.

Prognosis

Similar to many leukemias, this disease progresses rapidly, and requires intensive therapy to control the disease.

Key Terms

Biopsy

Surgical removal of tissue for examination.

Hematinic

Nutrients like iron, folic acid, and vitamin B that stimulate blood formation.

Infarct

Cell death caused when the blood supply is shut off from the effected cells.

Leukemia

Cancer of white blood cells.

Further Reading

For Your Information

Books

• Bennett, J. Claude and Fred Plum, ed. Cecil Textbook of Medicine. Philadelphia: W. B. Saunders, 1996.
• Lichtman, Marshall A. "Idiopathic Myelofibrosis." In Williams Hematology, edited by Ernest Beutler, et al. New York: McGraw-Hill, Inc., 1995, pp. 331-340.
• Linker, Charles A. "Blood." In Current Medical Diagnosis and Treatment, edited by Lawrence M. Tierney Jr., et al. Stamford, CT: Appleton & Lange, 1996, pp. 502-503.
• Spivak, Jerry L. "Polycythemia Vera and Other Myeloproliferative Disorders." In Harrison's Principles of Internal Medicine, edited by Kurt Isselbacher, et al. New York: McGraw-Hill, 1998, pp. 681-682.

Gale Encyclopedia of Medicine. Gale Research, 1999.