Seropositive rheumatoid arthritis (RA); Felty's syndrome
The cause of Felty syndrome is unknown. It is more common in people who have had rheumatoid arthritis (RA) for a long time. People with this syndrome are at risk for infection because they have a low white blood cell count.
Exams and Tests
A physical exam will show:
A complete blood count (CBC) with differential will show a low number of white blood cells called neutrophils. Nearly all people with Felty syndrome have a positive test for rheumatoid factor.
An abdominal ultrasound may confirm a swollen spleen.
In most cases, people who have this syndrome are not getting recommended treatment for RA. They may need other medicines to suppress their immune system and reduce the activity of their RA.
Methotrexate may improve the low neutrophil count. The drug rituximab has been successful in people who do not respond to methotrexate.
Granulocyte-colony stimulating factor (G-CSF) may raise the neutrophil count.
Some people benefit from removal of the spleen (splenectomy).
Without treatment, infections may continue to occur.
RA is likely to get worse.
Treating the RA, however, should improve Felty syndrome.
You may have infections that keep coming back.
Some people with Felty syndrome have increased numbers of large granular lymphocytes, also called LGL leukemia. This will be treated with methotrexate in many cases.
When to Contact a Medical Professional
Call your health care provider if you develop symptoms of this disorder.
Prompt treatment of RA with currently recommended medicines markedly decreases the risk of developing Felty syndrome.
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Myasoedova E, Turesson C, Matteson EL. Extraarticular features of rheumatoid arthritis. In: Hochberg MC, Gravallese EM, Silman AJ, Smolen JS, Weinblatt ME, Weisman MH, eds. Rheumatology. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 95.
Savola P, Brück O, Olson T, et al. Somatic STAT3 mutations in Felty syndrome: an implication for a common pathogenesis with large granular lymphocyte leukemia. Haematologica. 2018;103(2):304-312. PMID: 29217783 www.ncbi.nlm.nih.gov/pubmed/29217783.
Wang CR, Chiu YC, Chen YC. Successful treatment of refractory neutropenia in Felty's syndrome with rituximab. Scand J Rheumatol. 2018;47(4):340-341. PMID: 28753121 www.ncbi.nlm.nih.gov/pubmed/28753121.
Review Date: 4/8/2019
Reviewed By: Gordon A. Starkebaum, MD, MACR, ABIM Board Certified in Rheumatology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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