Background: Relapsing polychondritis (RP) is an uncommon autoimmune inflammatory disease that may affect cartilage throughout the body.

Methods: We report on a case of fever of unknown origin in which 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) was performed to make a diagnosis of RP.

Conclusions: Our case demonstrates that the use of 18F-FDG PET/CT is a useful diagnostic tool to accurately determine the extent of inflammation throughout the body which can be identified by an increased 18F-FDG uptake.