Fever of unknown origin: evaluation of 110 classical and HIV-associated cases in the last decade.

Background: Fever is one of the critical symptoms of collagen vascular diseases, malignancies, and infectious diseases. Patients with a fever of unknown origin (FUO) were evaluated to determine the etiology.

Methods: In this study, 110 cases with FUO who were admitted to two hospitals with a total of 800 beds, in which 5000 daily outpatient patients were admitted between 2006 and 2016 have been evaluated retrospectively. Anamnesis and the findings were obtained from hospital records. Patients with a temperature higher than 38.3°C and lasting three weeks or longer without diagnosis despite one week of investigation in the hospital were included as FUO cases in this study. Nosocomial and neutropenic cases were excluded from the present study.

Results: Fifty-seven patients were male (52%), and the mean age was 40.2 ± 17.2. The distribution of the classic and HIV-associated cases was 85 (77.3%) and 18 (16.4%). Tuberculosis (TB) was the most frequent disease in both groups. The etiology was infectious in 68.2%, autoimmune in 14.5%, and neoplastic in 5.4%. There was no case of collagen vascular disease in the HIV-associated FUO group.

Conclusion: As a result of our study, infectious diseases and TB were still the leading factors that caused FUO. TB has been notably found higher in the HIV-associated group than the classic group. FUO is usually either a rare cause or an unusual clinical presentation of a well-known infectious disease in Turkey. Therefore, it should be noted that various manifestations of extra-pulmonary tuberculosis may be considered a FUO case.