[Fever of unknown origin in malignancies].

Fever is a common symptom in patients with malignancies. On the one hand it may be an (initial) symptom of cancer, on the other hand it may occur as a side effect of chemotherapy. Often a precise cause of fever can not be established and in these cases febrile temperatures >38.3 degrees C without proof of infection or relapse/progress of tumor is defined as fever of unknown origin. Especially hematologic neoplasias are accompanied by fever. Here, neoplastic fever must be distinguished from fever following immunosuppressive chemotherapy. In the latter severe infections due to neutropenia induced by cytoreductive chemotherapy is often identified as the cause of fever. These patients display a high morbidity and mortality, especially if an empiric anti-infectious treatment is not administered in time. A meticulous diagnostic work-up is therefore necessary, and until proven otherwise, an infectious cause must be considered and empiric antibiotic treatment initiated.