Pyrexia of unknown origin

• Published in: Medicine (Abingdon. 1995, UK ed.) Vol. 49; no. 11; pp. 719 - 722
• Main Authors: Mulders-Manders, Catharina M., Banerjee, Rishi Raj
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2021
• Subjects: Fever of unknown origin; fever syndrome; inflammation of unknown origin; potential diagnostic clues; pyrexia of unknown origin; pyrexia of unknown origin; inflammation of unknown origin; Fever of unknown origin; potential diagnostic clues; fever syndrome
• ISSN: 1357-3039; 1878-9390
• DOI: 10.1016/j.mpmed.2021.08.003

Pyrexia or fever of unknown origin is defined as prolonged fever in an immunocompetent patient that has an unknown cause despite standard investigations. Infections, non-infectious inflammatory diseases, malignancy and other diseases can all cause pyrexia of unknown origin. The diagnostic work-up is based on the identification of potential diagnostic clues, and further investigation is based on the differential diagnosis of these clues. When diagnostic clues are absent, 18F-FDG-PET-CT is the single test with the highest contributory value, aiding final diagnosis in half of all patients. In Western Europe, up to 50% of patients remain without a diagnosis despite extensive investigation. Mortality is low in undiagnosed cases, and spontaneous resolution of fever is relatively common.