[Low-grade fever of protracted course. Retrospective study of 30 cases and reflections for a low-cost management]

The objects of this paper were the following: 1) to establish in a group of persistent (over four weeks) low grade fever (LGF) patients the percentage of cases in which a definite diagnosis could not be made; 2) where a definite diagnosis could be made, to describe the most commonly occurring diseases; 3) to follow up the uncertain diagnosis cases for at least two years. Thirty cases of persistent LGF were retrospectively studied. They did not include drug hyper-dysthermia and temporary and/or metabolic vasomotor reactions. The data suggest that: 1) two thirds of persistent LGF are likely not to be definitely diagnosed; 2) some certain diagnoses were: dental granulomas, mycobacteria infections, thyroiditis, factitious fever, rheumatic polymyalgia, Hodgkin's lymphoma and pulmonary thromboembolism; 3) in 14/19 undiagnosed cases the fever subsided permanently, without any treatment, within one year, whereas it persisted in 5/19, but no deterioration of the overall clinical status was observed; 4) although some of the undiagnosed cases were examined elsewhere, a certain diagnosis was never achieved in spite of their undergoing sophisticated and expensive clinical, laboratory and X-ray tests. Therefore it is concluded that: 1) persistent LGF should be managed more conservatively than fever of unknown origin so as to preserve resources; 2) some diseases should be included in the differential diagnoses from the beginning of the initial clinical work up; 3) undiagnosed LGF fever either subsides and returns to normal within one year or the fever persists, but no deterioration of the clinical and performance status is likely to occur.