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.
- General feeling of discomfort (malaise)
- Weakness in leg or arm
- Loss of appetite
- Unintentional weight loss
- Ulcers in the skin
- Joint swelling, stiffness, pain, and deformity
- Recurrent infections
- Red eye with burning or discharge
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
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.
Bellistri JP, Muscarella P. Splenectomy for hematologic disorders. In: Cameron JL, Cameron AM, eds. Current Surgical Therapy. 12th ed. Philadelphia, PA: Elsevier; 2017:603-610.
Erickson AR, Cannella AC, Mikuls TR. Clinical features of rheumatoid arthritis. In: Firestein GS, Budd RC, Gabriel SE, McInnes IB, O'Dell JR, eds. Kelley and Firestein's Textbook of Rheumatology. 10th ed. Philadelphia, PA: Elsevier; 2017:chap 70.
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 www.ncbi.nlm.nih.gov/pubmed/29222254.
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.