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Felty Syndrome

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Synonyms of Felty Syndrome

Disorder Subdivisions

General Discussion

Felty syndrome is usually described as associated with or a complication of rheumatoid arthritis. This disorder is generally defined by the presence of three conditions: rheumatoid arthritis (RA), an enlarged spleen (spenomelgaly) and a low white blood cell count (neutropenia). The presence of RA gives rise to painful, stiff and swollen joints. A low white blood cell count, especially when accompanied by an abnormally large spleen, leads to a greater chance for infections. Other symptoms associated with Felty syndrome may include fatigue, fever, weight loss, and/or discoloration of patches of skin (brown pigmentation). The exact cause of Felty syndrome is unknown. It is believed to be an autoimmune disorder that may be genetically transmitted as an autosomal dominant trait.


The symptoms of Felty syndrome are similar to those of rheumatoid arthritis. Patients suffer from painful, stiff, and swollen joints, most commonly in the joints of the hands, feet, and arms. In some affected individuals, Felty syndrome may develop during a period when the symptoms and physical findings associated with rheumatoid arthritis have subsided or are not present. In this case, Felty syndrome may remain undiagnosed. In more rare instances, the development of Felty syndrome may precede the development of the symptoms and physical findings associated with rheumatoid arthritis.

Felty syndrome is also characterized by an abnormally enlarged spleen (splenomegaly) and abnormally low levels of certain white blood cells (neutropenia). As a result of neutropenia, affected individuals are increasingly susceptible to certain infections.

Individuals with Felty syndrome may also experience fever, weight loss, and/or fatigue. In some cases, affected individuals may have discoloration of the skin, particularly of the leg (abnormal brown pigmentation), sores (ulcers) on the lower leg, and/or an abnormally large liver (hepatomegaly). In addition, affected individuals may have abnormally low levels of circulating red blood cells (anemia), a decrease in circulating blood platelets that assist in blood clotting functions (thrombocytopenia), and/or inflammation of the blood vessels (vasculitis). (For more information on this disorder, choose "Vasculitis" as your search term in the Rare Disease Database.) In rare cases, eye abnormalities have been associated with Felty syndrome.


The exact causes of Felty syndrome are not clear at this time. Scientists believe that the blood cell abnormalities, an allergy, or some unknown immunity disturbance may lead to the frequent infections that are commonly associated with this disorder. These clinicians think that Felty syndrome may be an autoimmune disorder. Autoimmune disorders occur when the body's natural defenses (antibodies) against invading or "foreign" organisms begin to attack the body's own tissue, often for unknown reasons.

At least some cases of Felty syndrome are thought to be genetically determined. Some studies of families with Felty syndrome across several generations lead clinical geneticists to suggest that a spontaneous mutation may occur that is transmitted as an autosomal dominant trait. However, the character of the mutant gene and its location has not been determined.

Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated "p" and a long arm designated "q". Chromosomes are further sub-divided into many bands that are numbered. For exampled, "chromosome 11p13" refers to band 13 on the short arm of chromosome 11. The numbered bands specify the location of the thousands of genes that are present on each chromosome.

Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.

Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.

Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the diseases, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. This risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.

All individuals carry a few abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Affected Populations

It is estimated that 1 to 3 percent of all patients with rheumatoid arthritis are affected by Felty syndrome. This is a large number, but most of these go undiagnosed. The disorder is about three times more common in women than in men. Felty syndrome is not found as frequently among those of African descent as among Caucasian populations. The disorder generally affects persons 50 to 70 years of age.

Related Disorders

The differential diagnosis of Felty syndrome may include sarcoidosis, amyloidosis, reactions to certain drugs, and/or myeloproliferative disorders. (For more information on these disorders, choose "Sarcoidosis" or "Amyloidosis" as your search term in the Rare Disease Database.)

Standard Therapies

Felty syndrome is usually diagnosed as a result of a thorough clinical evaluation, a detailed patient history, and the identification of the classic triad of physical findings (i.e. the presence of rheumatoid arthritis, low white blood count, and splenomegaly).

The treatment of Felty syndrome is symptomatic and supportive. Rheumatoid arthritis should be treated as it would in the absence of Felty syndrome (e.g. bedrest, appropriate exercise, heat treatments, gold salts, nonsteroidal anti-inflammatory drugs (NSAIDS), penicillamine, etc).

In many cases, treatment may include removal of the spleen (splenectomy). Splenectomy has had beneficial effects on anemia, thrombocytopenia, neutropenia, and/or chronic infections often associated with Felty syndrome. However, according to the medical literature, the long-term value of this procedure is not yet clear.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov . All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Toll free: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact: www.centerwatch.com

Felty Syndrome Resources



Ditzel HJ. Felty Syndrome. In. NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA 2003:8-9.

Beers MH, Berkow R., eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:

Berkow R., ed. The Merck Manuel-Home Edition. 2nd ed. Whitehouse Station, NJ: Merck Research Laboratories; 2003:

Berliner N, Horowitz M, Loughran TP Jr. Congenital and acquired neutropenia. Hematology (AM Soc Hematol Educ Program). 2004;:63-79.

Balint GP, Balint PV. Felty syndrome. Best Pract Res Clin Rheumatol. 2004; 18:631-45.

Sanders S, Harisdangkul V. Leflunodie for the treatment of rheumatoid arthritis and autoimmunity. AM J Med Sci. 2002; 323:190-93.

Hellmich B, Schnabel A, GrossWL. Treatment of severe neutropenia due to Felty's syndrome or systemic lupus erythematosus with granulocyte colony-stimulating factor. Semin Arthritis Rheim. 1999;29:82-99

Almoallim H, Klinkhoff A. Long term outcome of treatment of Felty's syndrome with intramuscular gold: case reports and recommendations for management. J Rheumatol. 2005:32:20-26.

Hellmich B, Ciaglo A, Schatz H, et al. Schatz H et al. Antobodies against granulocyte-macrophage colony stimulating factor and interleukin-3 are rare in patients with felty's syndrome. Ann Rheum Dis. 2004;63:862-66.

Ishikawa K, Tsukada y, Tamura S, et al. Salazosulfapyridine-induced remission of Felty's syndrome along with significant reduction of neutrophil-bound immunoglobulin G. J Rheumatol. 2003;30:404-06.

Zakzook Sl, Yunus MB, Mulconrey DS. Hyperviscosity syndrome in rheumatoid arthritis with Felty's syndrome: case report and review of the literature. Clin Rheumatol. 2002;21:82-85.

Peng S. Felty's syndrome. Medical Encyclopedia. MedlinePlus. Update Date: 10/24/2003. 3pp. www.nlm.nih.gov/medlineplus/ency/article/000445/htm

McKusick VA, ed. Online Mendelian Inheritance In Man (OMIM). The Johns Hopkins University. Felty Syndrome. Entry Number; 134750. Last Edit Date; 10/9/2000

Report last updated: 2008/04/07 00:00:00 GMT+0