Cogan's syndrome mimicking acute Lyme arthritis.

A pediatric case of Cogan's syndrome mimicking acute Lyme arthritis is described. A 12-year-old black boy was admitted to the pediatric service for presumed right knee septic arthritis. Symptoms included acute pain and swelling with decreased range-of-motion. Although the patient's right knee symptoms and positive Lyme serology were consistent with a diagnosis of Lyme arthritis, the presence of sensorineural hearing loss and interstitial keratitis with inflammatory arthritis suggested a diagnosis of Cogan's syndrome. Subsequent Western blot analysis was negative for Borrelia burgdorferi antigens. The patient had dramatic clinical improvement of musculoskeletal and ophthalmologic complaints shortly after receiving high-dose corticosteroids, although residual sensorineural hearing loss persisted.