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:
- Swollen spleen
- Joints that show signs of RA
- Possibly swollen liver and lymph nodes
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
Contact 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.
Cameron J. Spleen. In: Cameron J, ed. Current Surgical Therapy. 14th ed. Philadelphia, PA: Elsevier; 2023:chap 10.
England BR, Mikuls TR. Clinical features of rheumatoid arthritis. In: Firestein GS, Budd RC, Gabriel SE, Koretzky GA, McInnes IB, O'Dell JR, eds. Firestein & Kelley's Textbook of Rheumatology. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 76.
Gazitt T, Loughran TP Jr. Chronic neutropenia in LGL leukemia and rheumatoid arthritis. Hematology Am Soc Hematol Educ Program. 2017;2017(1):181-186. PMID: 29222254
Myasoedova E, Matteson EL. Extraarticular features of rheumatoid arthritis. In: Hochberg MC, Gravallese EM, Smolen JS, van der Heijde D, Weinblatt ME, Weisman MH, eds. Rheumatology. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 91.
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
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
Last reviewed on: 4/30/2023
Reviewed by: Neil J. Gonter, MD, Assistant Professor of Medicine, Columbia University, New York, NY, and private practice specializing in Rheumatology at Rheumatology Associates of North Jersey, Teaneck, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.