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Felty syndrome is defined by the triad rheumatoid arthritis (RA), splenomegaly and granulocytopenia. It affects approximately 1% of patients with RA, most often few years after the onset of RA. Sex ratio females/males is 3:1 and the mean age at onset lies between 50 and 70 years. The pathophysiology of the syndrome remains scarcely understood. Some causes of granulocytopenia have been incriminated like splenic sequestration, granulocyte destruction mediated by autoantibodies or immune complexes, hemophagocytosis or T-suppressor deficit. Particular attention should be paid to LGL (large granular lymphocyte) CD8+, CD57+ that are sometimes found in Felty syndrome. LGL leukemia leading to splenomegaly and granulocytopenia can be associated with rheumatoid arthritis and is then called "pseudo Felty" by some authors. However, for others, Felty syndrome and LGL leukemia associated with rheumatoid arthritis are the same disease. In any case, immunophenotyping and bone marrow aspiration should be done to rule out LGL leukemia. Apart from splenomegaly, the clinical presentation is characterized by increased extra-articular manifestations of rheumatoid arthritis. Infectious complications, which are essentially pulmonary and cutaneous are increased because of granulocytopenia and may be life-threatening. The incidence of non-Hodgkin lymphoma seems also to be higher. Biologically, rheumatoid factors are almost always present (>90%) and ANF (antinuclear factor), ANCA (antineutrophil cytoplasmic antibodies) and HLA DR4 association are frequent. The treatment of Felty syndrome is the same as that for rheumatoid arthritis. Immunosuppressive therapy (methotrexate, cyclophosphamide) is the most effective therapy; anti-TNF (tumor necrosis factor) has not been used widely enough to recommend it in Felty syndrome. When life-threatening, granulocytopenia can be treated by growth factors such as G-CSF (Granulocyte colony-stimulating factor) and by splenectomy in severe and intractable cases. |