Felty 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.

Symptoms include:

• General feeling of discomfort (malaise)
• Fatigue
• 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

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 their spleen (splenectomy).

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.

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.

Seropositive rheumatoid arthritis (RA); Felty's syndrome

Johnson TM, Mikuls TR, England BR. Clinical features of rheumatoid arthritis. In: Firestein GS, McInnes IB, Koretzky GA, Mikuls TR, Tuhina N, O'Dell JR, eds. Firestein & Kelley's Textbook of Rheumatology. 12th ed. Philadelphia, PA: Elsevier; 2025:chap 72.

McInnes IB. Rheumatoid arthritis. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 243.

Savola P, Bhattacharya D, Huuhtanen J. The spectrum of somatic mutations in large granular lymphocyte leukemia, rheumatoid arthritis, and Felty's syndrome. Semin Hematol. 2022;59(3):123-130. PMID: 36115688 pubmed.ncbi.nlm.nih.gov/36115688/.

Updated by: Diane M. Horowitz, MD, Rheumatology and Internal Medicine, Northwell Health, Great Neck, NY. 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.