Fever of unknown origin

Prolonged fever of unknown origin (FUO) identifies a pattern of fever that defined in 1961. The identification of the cause of FUO is a challenge in clinical practice despite recent advances in diagnostic techniques. No standardized diagnostic strategy could be determined. The diagnostic process should be guided by the potential diagnostic clues (PDCs) emerging from the history, meticulous physical examination and baseline tests. A standardized flow chart can be applied only in absence of PDCs or when the PDCs are contradictory. In the absence of clues, a staged diagnostic protocol was used to search elements contributing to the diagnosis (CT scan, scintigraphies, endoscopies and systematic biopsies). When diagnosis was not established and patient deteriorated, empiric therapeutic trial were started to presumptive diagnoses. Recently, the role of 18-FDG-PET scan as been intensively evaluated as a second-step investigation technique, as a part of structured diagnostic protocol, early after the initial clinical work-up and baseline biology, radiology and ultrasonography. This approach is based on the fact that reaching a diagnosis is extremely difficult in patients with FUO and that this tracer accumulates in infectious, neoplastic and non-infectious inflammatory disorders. (C) 2009 Elsevier Masson SAS. All rights reserved.