[CME/Answers: Musculoskeletal Manifestations of Lyme Disease]

Lyme disease is the most common vector-borne illness in Switzerland and Lyme arthritis the most prevalent manifestation of late-stage Lyme disease. It presents as a monoarthitis or oligoarthritis in large joints, often involving the knee. Such a clinical presentation, together with positive Lyme serologies or polymerase chain reactions from synovial fluid/tissue, is considered diagnostic. If there is no tick bite or erythema migrans in the patient's history the diagnosis can be challenging due to the many differential diagnoses. The initial treatment is a prolonged course of oral antibiotics.