Successful abatacept treatment for Felty's syndrome in a patient with rheumatoid arthritis.

We report the case of a 69-year-old man with a 38-year history of rheumatoid arthritis (RA), who developed Felty's syndrome, successful treatment with abatacept (ABT). He was treated with etanercept 50 mg/w and methotrexate 8 mg/w for the past 5 years. He was suffered from febrile neutropenia 6 months ago. Etanercept and methotrexate was discontinued 3 months ago, however, neutrophil count was not changed. Abdominal ultrasound showed splenomegaly, the diagnosis of Felty's syndrome was made. Granulocyte colony-stimulating factor therapy showed no effect on neutropenia, he was treated with ABT. After ABT therapy, absolute neutrophil count was elevated 234/μL to 1840/μL.