Successful Treatment of Pseudoseptic Arthritis Contained Massive Purulent Fluid with Adalimumab in Rheumatoid Arthritis

摘要

In pseudoseptic arthritis, the synovial fluid might look purulent, but is sterile, gram stains show no organisms, and synovial fluid cultures are negative.1 Physicians generally think of septic arthritis of Rheumatoid arthritis (RA) presenting with purulent synovial fluid with painful joint swelling and significantly increased synovial fluid leukocyte. We encountered a patient with acute wrist monoarthritis from which we obtained seemingly purulent synovial fluid, but in whom ultimately demonstrated an exacerbation of RA which was successfully treated with adalimumab. A 41-year-old man with RA presented with pain in his swollen left hand that had begun 2 weeks previously. His RA had been diagnosed 4 years before.At the time his wrist pain began, he was taking leflunomide (10 mg/day) and tacrolimus (1 mg/day) and 10mg of methotrexate weekly considered RA to be in remission. Upon presentation to the clinic, he had marked purulent synovial fluid in left carpal joints, from which 25 ml of brown opaque synovial fluid was aspirated (Fig. 1A). The microscopy of the synovial fluid at presentation, and in all subsequent samples, showed no crystals. Synovial fluid analysis showed 64,000/ml white blood cells (WBCs; 90% polymorphonuclear cells) and 7,600/ml red blood cells (RBCs), glucose (9.8 mg/dL), no crystals, and a negative Gram stain. He was treated with oral cefpodoxime and weekly arthrocenteses. Despite persistent management, bullous lesions tend to deteriorate (Fig. 1B), especially the left dorsum of the hand and aspiration fluid was pyogenous. No infectious agents were found in synovial fluid or blood, and he was not improved with prolonged antibiotic therapy or conventional Disease Modifying Anti-Rheumatic Drugs (DMARDs). An MRI of the left wrist showed large joint effusion, synovial thickening, and pannus formation with enhancement, multifocal marginal carpal bone erosion in distal radioulnar, dorsal radiocarpal and mid carpal joints (Fig. 2A). Cultures of synovial fluid, blood, and urine grew no organisms. We judged that this finding confirmed an inflammatory reaction. Antibiotics were discontinued and the patient was prescribed a double dose of leflunomide and tacrolimus. One months later, he still had difficulty with hand grip and effusion with purulent sterile fluid. Then he was treated with adalimumab. After 6 months of administration, his effusion was resolved (Fig. 2B). There is no definitive method to differentiate between septic arthritis and inflammatory arthritis. In patients with RA, joint fluid analysis typically reveals inflammation (white blood cell count >2000/µL, generally in the range of 1500–25,000/µL) characterized by a predominance of polymorphonuclear cells.2 Cell counts in excess of 25,000 may occur in very active disease, but levels over 25,000 should alert the clinician to the increased possibility of coexisting infection.3 In conclusion, pseudoseptic arthritis is a syndrome that should be kept in mind when faced with patient with long standing inflammatory condition such as rheumatoid arthritis who present with an acute monoarthritis with no known bacterial source for septic arthritis. This syndrome is an entity to be aware of, and truly the only way to differentiate pseudosepsis from septic arthritis is by negative synovial fluid culture and response to immuno-modulator not to antibiotics.