[Differential diagnosis in fever of unknown origin].

Fever is one of the most frequent and important symptoms in pediatrics. Most cases are caused by self-limiting viral or easily treatable bacterial infections. If after 5-7 days no cause of the ongoing fever has been found, the condition is termed fever of unknown origin, a working diagnosis which often poses a diagnostic challenge. The ultimate cause may be an infectious disease, a chronic inflammatory disorder, a malignancy, or another rare disease. The cause may also remain obscure or the fever can finally disappear. Here we elaborate the diagnostic work-up and symptomatic treatment.