Diagnostic Complexity of Adult-Onset Still's Disease in the Setting of Nosocomial Infection and Antibiotic Hypersensitivity.

Adult-onset Still's disease (AOSD) is a diagnosis of exclusion and may be difficult to recognize when infection and drug hypersensitivity coexist. A 31-year-old woman presented with high-spiking fever, arthralgia, and a generalized eruption after ampicillin exposure. Initial investigations for infection and autoimmune disease were unrevealing. Her clinical course was subsequently complicated by severe nosocomial infection and recurrent eruptions during antibiotic treatment. Recurrent high-spiking fever and a fever-associated eruption after apparent clinical improvement of infection supported AOSD as the working diagnosis. However, uncertainty regarding the rash and overlapping infectious and drug-related features limited confident retrospective confirmation of the Yamaguchi classification criteria. Following infection control, intravenous methylprednisolone pulse therapy followed by cyclosporine resulted in rapid clinical improvement. This case illustrates the diagnostic complexity of AOSD in the setting of nosocomial infection and antibiotic hypersensitivity.