Adult-onset Still’s Disease: A Case Report

Pyrexia of unknown origin refers to a fever of over 38.3°C on multiple occasions for at least three weeks without a known aetiology, even after a week of hospitalization. Adult-onset Still's disease is a rare systemic auto-inflammatory disorder with a prevalence of 0.6/100,000 population characterized by spiking fever, arthralgia or arthritis and maculopapular rash. Here, we present a case of 19 years-old female with pyrexia of unknown origin. With no identifiable cause and fulfilled criteria of Yamaguchi, a diagnosis of adult-onset Still's disease was made. She was treated with IV steroid therapy followed by oral steroids and non-steroidal anti-inflammatory drugs. This case highlights the awareness of the possible adult-onset Still's disease patients with pyrexia of unknown origin. However, one should remain cautious and exclude all other differentials before making this diagnosis, as the actual disease may masquerade as adult-onset Still's disease criteria.