A rare complication of rheumatoid arthritis (RA) characterized by an enlarged spleen and a low white blood cell count. Because of their low levels of white blood cells, people with Felty syndrome are at high risk for bacterial infections, particularly in the lungs, skin, and urinary tract. Leg ulcers are another complication of Felty syndrome. Felty syndrome affects approximately 1% to 3% of people with RA and usually occurs in those with longstanding, severe, and rheumatoid-factor–positive RA. It is most prevalent in women around 60 years of age.
Doctors usually treat Felty syndrome by addressing the underlying RA. Most cases of Felty syndrome are therefore treated with disease-modifying antirheumatic drugs such as methotrexate (Rheumatrex, Trexall) or leflunomide (Arava), and/or with biologic drugs, such as etanercept (Enbrel) or infliximab (Remicade). Antibiotics may be used to treat infections. In people with severe infections, injections of granulocyte stimulating factor, which increases the number of white blood cells in the blood, may be helpful. Sometimes surgical removal of the spleen offers temporary improvement.