[Recurrent fever of unknown etiology lasting more than 6 months. Report on 85 patients].

85 patients having recurrent fever of unclarified aetiology of more than 38.5 degrees C for more than 6 months were examined in a prospective study. Of these, 10 had an inflammation due to pathogens, 12 a malignant disease, 15 a collagenous or inflammatory vascular disease, while 9 had various diseases, 5 a familial Mediterranean fever and 18 a "periodic fever". In 16 patients, in most of whom the course of the disease extended over several years, the cause of the fever could not be clarified. Among the patients with polycyclic fever over many years or decades, alternating with symptom-free intervals, one can differentiate especially the systemic Still's syndrome, which also occurs in adults and which is identical with the so-called subsepsis allergica, the familial Mediterranean fever and the "periodic fever". There are no satisfactory pointers towards the existence of a relapsing fever of its own caused by an increase of unconjugated aetiocholanolone in the plasma ("aetiocholanolone fever").