[Large vessel vasculitis in a patient with fever of unknown origin]

Fever of unknown origin (FUO) is a challenging diagnosis. Recently, 18F-fluorodeoxyglucose positron-emission tomography (FDG-PET) has emerged as an useful exam to its diagnosis. The authors present a case of a 64-years-old woman with an aortic mechanical valve that was admitted to the internal medicine department because of fever, weakness and weight loss of 2 months duration. Her physical examination was unremarkable. Laboratory findings showed microcytic anemia, no leukocytosis, and elevated C-reactive protein and erythrocyte sedimentation rate. Microbiology, immunology and imaging studies were normal. A FDG-PET was performed, which showed 18F-FDG uptake in aorta and its branches arterial wall. Treatment with corticosteroids was started with good response. This exam, although not sensitive for temporal arteritis when only smaller vessels are involved, permits the diagnosis of large vessel vasculitis with involvement of arteries that can not be biopsied.