[Fever of unknown origin in internal medicine. The experience of Spanish authors over 20 years].

The diseases responsible of fever of unknown origin (FUO) have changed in the last years. With the object of study the etiologic spectrum and diagnostic attitude in the FUO in a national level in the last 25 years, we has revised 14 articles of FUO realized in Internal Medicine published from 1970 to 1995, without aids patients. We use MEDLINE and Indice Médico Español to search the publications about FUO. In 14 articles, 914 cases of FUO was evaluated, the infection was the principal cause (41.2%), followed by tumor (19.2%) and collagenoses/vasculitis (13.7%). In the infection group, the disease more frequent was the tuberculosis (134/377) (35.5%) follow by brucellosis (15.6%) y abscesses (11.6%). Half of malignancy group was due to lymphoma. Systemic lupus erythematous, polyarteritis nodosa and temporal arteritis were caused of FUO in 28.8%, 21.6% y 20% of collagenoses/vasculitis group. In the miscellaneous group emphasized granulomatous diseases (38.8%) (including sarcoidosis, idiopathic granulomatous hepatitis and chronic granulomatous disease). The improve of diagnostic procedures has conditioned a change of spectrum of the diseases, with a decrease of infectious causes (as brucellosis or salmonellosis) and increase or neoplasia and collagenoses/vasculitis (except lupus).