Fever of unknown origin as initial manifestation of large vessel giant cell arteritis: diagnosis by colour-coded sonography and 18-FDG-PET.

OBJECTIVES To evaluate the clinical characteristics and imaging results (CDS, 18-FDG-PET) of patients with large vessel giant cell arteritis (LV-GCA) presenting as fever of unknown origin (FUO). METHODS From a series of 82 patients with GCA we identified 8 patients with FUO as initial disease manifestation. Clinical characteristics and results of CDS and 18-FDG-PET were analysed. Patients with FUO and those with other clinical manifestations of GCA were compared. RESULTS 18-FDG-PET-scans were available for 6/8 patients, revealing enhanced tracer uptake of the thoracic aorta and the aortic branches in all patients. CDS was performed in 8/8 patients, with detection of hypoechogenic wall thickening related to LV-GCA in 7/8 patients. Subjects with FUO were significantly younger (60.9 vs. 69.3 years, p<0.01) and had a stronger humoral inflammatory response (CRP 12.6 vs. 7.1 mg/dl, p<0.01; ESR 110 vs. 71 mm/hour, p<0.01), when compared to the other GCA-patients. CONCLUSIONS LV-GCA should be considered as important differential diagnosis in patients with FUO. In addition to 18-FDG-PET, which is known to be a valuable method in the diagnostic work-up of FUO, we recommend CDS of the supraaortal and femoropopliteal arteries for the initial diagnostic work-up.