Fever of unknown origin--etiology and diagnostic algorithm

Fever of unknown origin is a frequent and significant diagnostic problem often faced by physicians. The first part of the text is dedicated to its definition and wide-ranging aetiology. On the one hand, fever may be a banal and benign condition, on the other, it can be the symptom of a life threatening disease. The second part presents our suggestions for diagnostic approach to fever of unknown origin. We believe this text may become a useful tool for this extremely complex and interesting differential diagnostic. In view of extension and complexity of the topic, the text of this part is presented in full.