Fever of unknown origin (FUO) and biologic inflammatory syndrome of unknown origin (SII) are two frequent causes of hospitalization or consultation in infectious disease unit and internal medicine.

There are many etiologies, in four categories: infections, auto-immune disease, cancer and miscellaneous causes. Currently there is no specifics recommendations to follow a "diagnosis way" of FUO and SII.

Purpose: Evaluation of clinical practices in the diagnosis of fever and biologic inflammatory syndrome of unknown origin, in two units of the University Grenoble Hospital.

Fever of unknown origin (FUO) and biologic inflammatory syndrome of unknown origin (SII) are two frequent causes of hospitalization or consultation in infectious disease unit and internal medicine unit.

The initial definition for FUO was proposed by Petersdorf and Beeson in 1961 : "fever > 38,3°C, permanent or recurrent, for more than 3 weeks, without diagnosis after one week hospitalisation and explorations". This definition has been updated by Durack and Street in 1991 who distinguish "classics FUO" from 3 other categories : nosocomial, patient with HIV and neutropenia. They also choose an other way of diagnosis : 3 days of investigations in hospital OR in consultation.

Finally, Knokaert and al. proposed a new definition, based on a qualitative criterion: No diagnosis after a first step and complete clinical and paraclinical check up.

The evolution of FUO's prevalence is not describe so much. There are many etiologies, classified in four categories: infections, auto-immune disease, cancer and miscellaneous causes. The distribution of FUO's causes may change according to geographical localisation, and seems to evolve over time, with apparition of new infectious and inflammatory diseases, and the advent of new diagnosis tools.

Currently there is no specifics recommendations to follow a "diagnosis way" of FUO and SII. It starts with a complete physical examination and some first lign further exams. Without diagnosis, paraclinical explorations are continued with more specific exams, according to the presence or the absence of diagnosis clues.

The TEP scanner has shown a great value in the diagnosis of FUO, and trend to be more performed.

Investigators propose to evaluate professional practices in the diagnosis of fever and biologic inflammatory syndrome of unknown origin, and especially the interest of TEP Scan, in two units of the University Grenoble Hospital.

Investigators will study prevalence of FUO and SII, and of each causes of FUO and SII, and the prognosis of patients with FUO and SII, according to the presence or the absence of final diagnosis, as well as the economic impact of the different complementary exams.

Inclusion Criteria:

• patients > 18 years old
• with fever> 38.5°C and/or CRP> 5mg/L for more than a week
• with standard check-up that did not allow a causal diagnosis

Exclusion Criteria:

• immunosuppression : HIV, neutropenia, known cancer with chemotherapy, immunosuppressive treatment or corticotherapy (> 10mg/L for >3 weeks)
• nosocomial fever
• pregnant women
• patients who are not able to sign a consent

patient with fever and biologic inflammatory syndrome of unknown origin for more than a week