Fever of unknown origin (FUO) was traditionally characterized by a temperature exceeding 38.3 °C on at least three occasions over a period of at least three weeks, with no apparent cause despite one week of inpatient investigation [1]. It has been categorized into infectious, non-infectious inflammatory diseases, malignancies, and other miscellaneous disorders. In recent years, new definitions and diagnostic methods have been incorporated into clinical practice. Especially with the progress in genetic research, there is a growing recognition of cases linked to mutations in inflammasome proteins as a cause of FUO.
