抄録
We experienced a rare case of a solitary bone cyst in a 65-year old female patient with a 37-year history of rheumatoid arthritis (RA), and who was treated with biologic agents. Since December 2012, the patient had experienced sustained rest pain in her left arm despite using non-steroidal anti-inflammatory drugs. Her RA disease activity was controlled as evidenced by a normal C-reactive protein (CRP) level of 0.13 mg/dL, and a Disease Activity Score (DAS) 28 of 2.4, whilst using methotrexate 12 mg/week, and abatacept 500 mg intravenously. There was no swelling or tenderness observed in her left arm, and the range of motion (ROM) of her left shoulder was normal with a negative impingement test. Her Japanese Orthopedic Association (JOA) score was 67 points consisting of 10 points for pain, 12 points for function, 25 points for ROM, 5 points for radiographic changes, and 15 points for stability, respectively. A T2-weighted short-tau inversion recovery magnetic resonance imaging scan showed a 3 × 4 cm homologous high intensity area, which was suspected to be a solitary bone cyst in her left humerus. Surgical decompression and drainage of the cyst was performed using an absorbable cannulated screw. One month postoperatively the patient's left arm pain had resolved with a normal ROM of the shoulder, and a JOA score of 99.
