Fever of unknown origin: Importance of 18F-FDG PET/CT in the diagnosis of a late infectious complication after aneurysm bypass.

Persistent blood flow in aneurysmal sac after bypass-exclusion is well documented in the literature. Aneurysm enlargement, local compressive symptoms and even sac rupture are commonly described complications. Late secondary infection of popliteal artery aneurysm (PAA) following ligation and venous bypass is exceptional. We report the case of late PAA infection six years after bypass-exclusion in a 75 year-old man which was diagnosed by 18F-FDG PET/CT. The patient was successfully treated by aneurysm resection and antibiotics. The diagnosis of popliteal aneurysm infection is often clinical, echographic and sonographic, but computed tomography scan can be false negative in chronic low-grade infection. 18F-FDG PET/CT is able to accurately diagnose and localize infection with high sensibility and specificity.