Felty syndrome is a disorder that is defined by the presence of 3 different conditions:1,2
- Rheumatoid arthritis (RA)
- An enlarged spleen
- Low white blood cell count
Other names for it include Felty’s syndrome or familial Felty’s syndrome. Doctors believe that it is an autoimmune disorder. The syndrome is also described as a complication of RA or as a condition linked to the disease.2
Doctors do not know the exact cause of Felty syndrome. Some cases of Felty syndrome may be genetic, or passed down through families. Studies of families with this syndrome show that it may be caused by an inherited genetic mutation. However, the exact gene or mutation and its location have not been found.1
People with Felty syndrome often have frequent infections. These may be caused by blood cell abnormalities, an allergy, or an immunity disturbance.1
How is Felty syndrome related to RA?
Rheumatoid arthritis is 1 of the factors that has to be present in Felty syndrome. In most cases, a person has RA for years before they develop Felty syndrome. In rare cases, RA and Felty syndrome develop at the same time. Many of the symptoms of the 2 conditions are similar. This may explain why Felty syndrome can go undiagnosed.3
About 1 to 3 percent of people with RA also live with Felty syndrome. Most remain undiagnosed. The syndrome usually affects those between the ages of 50 and 70. It is 3 times as common in women than men.1
Signs and symptoms of Felty syndrome
Felty syndrome shares many of the same signs and symptoms as RA. This can make diagnosis difficult. These may include:1-3
- Painful, stiff, and swollen joints
- Enlarged spleen
- Very low levels of certain white blood cells
- Fever
- Weight loss
- Fatigue
- Skin discoloration, especially the leg
- Low levels of red blood cells and/or platelets
- Infections
- Findings of long-term RA, like joint deformities
Complications of Felty syndrome may include:3
- Rupture of the spleen
- Life-threatening infection
- Toxicity from immunosuppressive drugs
- Gastrointestinal bleeding
Getting a diagnosis
A complete medical history should be taken by the doctor. This is especially true if the person has a history of RA. Family history can also be helpful. A family history of RA is common in those with Felty syndrome.2
A physical examination will be done, and lab work may be ordered. Bloodwork can help your doctor determine blood counts and other signs that help them make a diagnosis of Felty syndrome.2
How is Felty syndrome treated?
Felty syndrome is best treated by treating the underlying RA. This is usually done using immunosuppressive drugs. Treating the RA typically helps reduce the size of the spleen. Most of the drugs used to treat RA have also been found to treat Felty syndrome. This shows the relationship of the condition to the immune system.5
If the spleen is very enlarged, surgery may be necessary. If there is a life-threatening infection present, you might be admitted to a hospital. Depending on your symptoms, your doctor may consult with other specialists. This can include a rheumatologist, hematologist, or infectious disease specialist.5
