[Fever of unknown origin with a prolonged course (author's transl)]

Out of 110 cases of fever of unknown origin (FUO) that met Petersdorf and Beeson's criteria 15 patients were selected because of prolonged FUO with more than six months elapsed between admission and the final diagnosis. In this group of chronic FUO an etiological diagnosis was reached in 11 cases, distributed as follows: four cases with infections (two with toxoplasmosis, one with brucellosis, and another with a brain abscess); one with colon carcinoma; two with collagen-vascular diseases (systemic lupus erythematosus, temporal arteritis); and four with different diseases (two with familial mediterranean fever, one with idiopathic granulomatous disease, and another with factitious fever). In four cases no cause for the FUO could be determined. The procedures used to obtain the diagnosis were non-invasive in five cases (clinical course and serological tests), and invasive in another five (angiography, biopsies, and exploratory laparotomy). In one case the ethology could only be ascertained at autopsy. In the FUO with a prolonged course the peculiar etiological spectrum, the lesser yield of invasive procedures, and a mortality inferior to that of FUO in general all deserve special emphasis.