AB0648 REACTIVE ARTHRITIS IN SYPHILIS MIMICKING RHEUMATOID ARTHRITIS: A CASE REPORT

Background: Reactive arthritis is a form of spondyloarthritis with aseptic joint involvement occurring after a gastrointestinal or urogenital infection. Most commonly associated with Chlamydia trachomatis, Salmonella, Shigella, Campylobacter, and Yersinia. Syphilis is an infection caused by the spirochete Treponema pallidum and is not usually associated with reactive arthritis. Syphilis is a great imitator of other diseases due to its broad presentation including painless chancre, constitutional symptoms, adenopathy, rash, synovitis, neurological and ocular findings. Objectives: To discuss a patient who presented with symptoms of rheumatoid arthritis (RA) but was later diagnosed with syphilis. Methods: 31 year old male, former tobacco smoker, referred to Rheumatology for sudden onset joint pains, elevated anti-cyclic citrullinated peptide (anti-CCP), and elevated inflammatory markers. He reported pain in bilateral wrists, fingers, and right elbow for 6 weeks. Associated with 45 minutes of morning stiffness and new onset lower back pain without stiffness. He denied trauma, fever, chills, skin rash, dysuria, or diarrhea. Initiated trial naproxen 500mg twice a day only to have minimal relief. Patient is sexually active with men and was recently diagnosed with oropharyngeal gonorrhea treated with azithromycin 4 months prior. All other STI screening including syphilis, gonorrhea, HIV were negative at that time. Patient is on emtricitabine and tenofovir disoproxil fumarate for HIV pre-exposure prophylaxis. He denied family history of immune mediated conditions. Exam was significant for mild synovitis of both wrists and bilateral 2nd metacarpophalangeal joints. Initial labs revealed weakly positive anti-CCP 21 (normal Results: Lumbar puncture showed cerebral spinal fluid with 260 red blood cells, 1 white blood cell, 27mg/dL protein, 60mg/dL glucose, non reactive VDRL, reactive pallidum IgG antibody, and negative cultures. Meningitis and encephalitis panels were negative. Patient completed a 14 day course of IV penicillin G with complete remission of joint pain, visual symptoms, and normalization of anti-CCP, ESR, and CRP. Conclusion: This case highlights how syphilis may mimic signs and symptoms of RA including symmetrical small joint pain, morning stiffness, elevated inflammatory markers, and positive anti-CCP. Anti-CCP is >96% specific for RA but was a false positive in this patient. There have only been few reported cases noting positive anti-CCP with reactive arthritis. This is a rare case of reactive arthritis secondary to syphilis with resolution of symptoms upon treating the syphilis. References: [1]Carter JD. Treating reactive arthritis: insights for the clinician. Ther Adv Musculoskelet Dis. 2010 Feb;2(1):45-54. [2]Cohen SE, Klausner JD, Engelman J, Philip S. Syphilis in the modern era: an update for physicians. Infect Dis Clin North Am. 2013 Dec;27(4):705-22. [3]Singh Sangha M, Wright ML, Ciurtin C. Strongly positive anti-CCP antibodies in patients with sacroiliitis or reactive arthritis post-E. coli infection: A mini case-series based review. Int J Rheum Dis. 2018 Jan;21(1):315-321. Disclosure of Interests: None declared.