Case report Felty's syndrome associated with high levels of IgA rheumatoid factor

SUMMARY A 64-year-old woman with rheumatoid arthritis developed Felty's syndrome. Her serum contained large amounts of IgA rheumatoid factor (RF) but insignificant levels of IgM-RF and IgG-RF. It is postulated that the high levels of IgA-RF may have contributed to the neutropenia. The association of chronic (rheumatoid) arthritis, splenomegaly, and leukopenia was first described by Felty in 1924.1 Most patients with Felty's syndrome have high levels of IgM rheumatoid factor (RF) in their sera,2 a condition which, although not part of the syndrome, has been implicated as one of the causes of the leukopenia.3 We report here the case of a patient with Felty's syndrome whose serum con-tained large amounts of IgA-RF but insignificant levels of IgM-RF and IgG-RF. We postulate that the high levels of IgA-RF may have contributed to the neutropenia in this case. Case report A 64-year-old Caucasian woman presented to the rheumatology clinic with a 6-month history of pain in the left shoulder. Subsequently she developed synovitis in the knees, wrists, and hands. She had marked morning stiffness lasting for one hour and complained of anorexia and 2 kg loss of weight over this period. Investigations revealed a haemoglobin (Hb) of 13-0 g/dl a white cell count (WCC) of 5 6 x 109/l, and an erythrocyte sedimentation rate (ESR) of 57 mm in the first hour. Protein electrophoretic strip showed a raised gamma globulin. Immuno