Adult-Onset Still's Disease: Typical Presentation, Delayed Diagnosis.

Adult-onset Still's disease (AOSD) is an uncommon auto-inflammatory disease of unknown etiology, with a classical triad of fever, arthritis, and evanescent rash. Its low prevalence and lack of specific guidelines contribute to frequent delays in diagnosis and treatment. Clinical manifestations vary greatly between mainly systemic or articular symptoms and the clinical pattern between monocyclic, polycyclic, or chronic illness. Treatment options include non-steroid anti-inflammatory drugs (NSAIDs), systemic corticoids, disease-modifying anti-rheumatic drugs (DMARDs), and, more recently, biological agents directed at identified immune pathological pathways like anti-interleukin-1 (IL-1) or anti-tumor necrosis factor-alpha (TNF-alpha). We report a case of a 40-year-old male with persistent fever, polyarthralgia, sore throat, and rash for two weeks despite antibiotic treatment for suspected bacterial pharyngitis. During hospitalization and after extensive diagnostic workup, an AOSD diagnosis was made according to Yamaguchi's criteria and successfully managed with systemic corticoids.