Felty's syndrome.

Felty's syndrome (FS) comprises a triad of rheumatoid arthritis (RA), neutropenia and splenomegaly, occurring in less than 1% of RA patients. Clinically it is characterized by severe joint destruction contrasting with moderate or absent joint inflammation and severe extra-articular disease, including a high frequency of rheumatoid nodules, lymphadenopathy, hepatopathy, vasculitis, leg ulcers, skin pigmentation etc. Recurrent bacterial infections are mostly due to the severe, otherwise unexplained neutropenia. The cause of neutropenia lies in both decreased granulopoiesis and increased peripheral destruction of granulocytes. Recurrent infections may lead to increased mortality. Spontaneous remission of the syndrome also occurs. Over 95% of FS patients are positive for rheumatoid factor (RF), 47-100% are positive for antinuclear antibody (ANA), and 78% of patients have the HLA-DR4*0401 antigen. Some 30% of FS patients have large granular lymphocyte (LGL) expansion. LGL expansion associated with uncomplicated RA is immunogenetically and phenotypically very similar to but clinically different from FS. Neutropenia of FS can be effectively treated with disease-modifying anti-rheumatic drugs (DMARDs), the widest experience being with methotrexate (MTX). Results of treatment with granulocyte colony-stimulating factor (G-CSF) are encouraging, but there is no experience with other biological agents. Splenectomy results in immediate improvement of neutropenia in 80% of the patients, but the rate of infection decreases to a lesser degree.