CASE REPORT Monoarticular septic arthritis in a patient with juvenile rheumatoid arthritis under etanercept treatment Kai-Cheng Lin • Chi-Di Liang • Kuender D. Yang • Hong-Ren Yu • Ho-Chang Kuo Received: 28 December 2009 / Accepted: 12 March 2010 / Published online: 28 March 2010 Ó Springer-Verlag 2010 Abstract A 7-year-old girl with polyarticular type juve- nile rheumatoid arthritis (JRA) presented with acute onset of right hip pain with limited range of motion and fever within the past two days. She had received etanercept for more than one year. Percutaneous arthrocentesis was per- formed and showed a white blood cell count of 84150/lL in the synovial fluid, although the culture showed negative results. The fever and right hip pain completely resolved after antibiotic treatment. Herein, we report the first case of septic monoarthritis of JRA under etanercept treatment. Keywords Etanercept Á Juvenile rheumatoid arthritis Á Septic arthritis Patient report A 7-year-old girl with a history of polyarticular type juvenile rheumatoid arthritis (JRA) had developed a pain- ful sensation over the right groin, thigh and knee area for 4 days. She felt slight right thigh soreness after playing on a slide in the playground of her school, but it was initially tolerable. However, a fever of around 38°C occurred 3 days later, accompanied by an increased sensation of pain over the right hip. The pain worsened overnight radiating to her right thigh, and the pain was exacerbated when she moved. The following morning it was noticed that she had difficulty in walking. The patient denied any sore throat, cough, rhinorrhea, chest pain, abdominal pain, dysuria, nocturia, changes in urinary, or bowel habits, or any history of recent trauma. No significant contact or travel history could be discerned. According to her past medical history, JRA had been diagnosed 3 years previously as polyarticular type; the involved joints including bilateral wrists, knees and ankles. Due to a poor response to disease modifying anti-rheu- matoid drugs (DMARDs: including methotrexate and prednisolone) for more than 1 year, she had been receiving etanercept as a 0.4 mg/kg subcutaneous injection twice a week for the past year. Well tolerance and arthritis treat- ment response were reported, with a normal erythrocyte sedimentation rate (ESR) during treatment with etanercept. We stopped methotrexate (MTX) and prednisolone 5 months after the initiation of etanercept. The initial appearance of the lower limbs showed remarkable swelling; erythematous change and local heat could be noted over the right thigh area. Due to the eta- nercept subcutaneous injections, there were multiple needle scars over bilateral anterior sides of the thigh area, without any inflammation signs that could be correlated with the K.-C. Lin Department of Family Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan K. D. Yang Á H.-R. Yu Á H.-C. Kuo (&) Division of Allergy, Immunology and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital- Kaohsiung Medical Center, 123 Ta-Pei Road, Niaosung Hsiang, Kaohsiung, Taiwan e-mail: erickuo48@yahoo.com.tw C.-D. Liang Division of Cardiology, Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan K. D. Yang Á H.-R. Yu Á H.-C. Kuo Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Kaohsiung, Taiwan 123 Rheumatol Int (2012) 32:1383–1385 DOI 10.1007/s00296-010-1459-5