We report diagnostic difficulties in the patient with fever of unknown origin. The patient was diagnosed with adult-onset Still's disease, which is a rare seronegative arthritis. Thirty seven year old patient was admitted to the hospital because of symptoms lasting for 6 weeks: fever, evanescent skin rash, arthritis and sore throat with the suspicion of fever of unknown origin. After exclusion the infectious aetiology, Still's adult-onset disease was recognised based on clinical picture, biochemical, serological and radiography, sonography results and after reumatological consultation. Treatment with nonsteroidal anti-inflammatory drugs was introduced with good clinical effect.
Diagnosis of fever of unknown origin is great challenge for doctors and requires realising careful anamnesis, performing overstandard examinations and good co-operation with consultants of other specialities.