An unsolved case of fever

Abstract

Fever of unknown origin (FUO) is extremely difficult to diagnose. It is defined as an illness lasting more than 3 weeks with a temperature exceeding 38 °C on several occasions and with an uncertain diagnosis after 1 week of intensive investigations in the hospital. The major causes of FUO are infection, neoplasm, and collagen vascular disease, but the percentages of each of these categories are subject to change due to improvements in diagnostic capability. The diagnostic workup of FUO is complex and, to date, there is no consensus published in the literature regarding guidelines as to the correct approach. A number of diagnostic tests and numerous non-invasive and invasive procedures, which however sometimes fail to explain the fever, are often necessary. In about 20% of cases of FUO the diagnosis is never established. In this article the case of a young man with fever of unknown origin is presented, the cause of which remains undiagnosed, in order to illustrate the difficulties of the diagnostic process. A “watch and wait” approach seems to be acceptable in a clinically stable patient for whom no diagnosis can be made after extensive investigation, and the prognosis is likely to be good.

Keywords

• Fever of unknown origin
• Differential diagnosis of fever
• Diagnostic workup