A 59-year-old asymptomatic man, first diagnosed to have rheumatoid arthritis 27 years ago, was admitted to hospital because of splenomegaly and neutropenia, first noted 2 years ago. Physical examination confirmed splenomegaly and also revealed pretibial hyperpigmentation, but no evidence of active rheumatoid arthritis.
Biochemical tests showed relative and absolute neutropenia (white blood cell count 2200/microliters; 1% neutrophils), thrombocytopenia and polyclonal hypergammaglobulinaemia. He also had increased erythrocyte sedimentation rate (38/92), a high titre of rheumatic factor (2128 IU/ml) and increased circulating immune-complexes (74%). Thoracic and abdominal computed tomography provided no evidence of malignant tumor. The spleen measured 15 x 7 x 10 cm. Bone-marrow biopsy from the iliac crest revealed abnormal maturation of granulopoiesis and marked lymphoid infiltration. The clinical triad of rheumatoid arthritis, splenomegaly and neutropenia are diagnostic of Felty's syndrome. As the patient was asymptomatic there was no indication for treatment.
Felty's syndrome is a rare condition demanding considerable effort in differential diagnosis.