Felty syndrome: A complication of long-standing rheumatoid arthritis characterized by the presence of 3 conditions -- rheumatoid arthritis, an enlarged spleen (splenomegaly), and an abnormally low white blood cell count. The white blood cells that are low are called granulocytes (or neutrophils).
Felty syndrome predisposes to infections such as pneumonia or skin infections, because of the low white counts. Ulcers in the skin over the legs can also complicate Felty syndrome. The cause of the syndrome is not known. White cells may be stored excessively in the spleen. especially in patients with Felty syndrome who have antibodies against granulocytes.
In Felty syndrome, the underlying rheumatoid arthritis is managed in the standard manner. Patients with severe infectious disease may benefit from weekly injections of granulocyte colony stimulating factor (G-CSF) to stimulate the production of granulocytes.