Author: Peter Bakes M.D. Educational Pearls: Some common causes of monoarticular arthritis include: crystal arthropathies (gout and pseudogout), infection (septic joint), reactive arthritis and acute presentations of chronic arthritides. Lyme disease usually presents with a targetoid lesion associated with constitutional symptoms. The common triad of symptoms associated with reactive arthritis (aka Reiter’s Syndrome) consists of conjunctivitis, urethritis, and arthritis. Reactive arthritis commonly presents with a history of  a GU infection (often chlamydia) or GI infection (Shigella, Campylobacter, Yersinia, Salmonella). It is more common in men and those between 20 and 40 years old. Treatment for reactive arthritis is usually supportive. References: www.emedicine.medscape.com/article/331347-overview