Other - PET scan for FUO detects incidental small breast lesion

Vasculitis is a frequent cause of fever of unknown origin (FUO). In this case, despite a very extensive diagnostic work-up no cause was found for this patient's fever. Her FDG PET scan clearly demonstrated vasculitis involving the aorta and large vessels, indicated in the image by the green arrows. Incidentally, a focal area of uptake was noticed in the right breast, which is identified by the blue arrow. Surgery with excisional biopsy revealed a 4 mm breast cancer that had been missed on mammography, ultrasound and MRI. Her vasculitis represented a paraneoplastic sign.

Only the PET•CT scan enabled a conclusive diagnosis and timely treatment of this patient with severe FUO, who remains disease free 3 years later.