PET-CT findings in large vessel vasculitis presenting as FUO, a case report

There are increasing data demonstrating the role of flourodeoxyglucose positron emission tomography with computerized tomography fusion ((18)FDG PET-CT) in the diagnosis of large vessel vasculitides, including Takayasu arteritis and giant cell arteritis (Hara et al. 1999; Blockmans et al. 1999; Turlakow et al. 2001]. We report a case of large vessel giant cell arteritis involving the major branches of the aorta as detected on (18)FDG PET-CT. A 56-year-old woman returning to the USA after visiting her native Iraq presented to our rheumatology department with fever of unknown origin (FUO) of 2-month duration, night sweats, and arthralgias. The patient did not have claudication; systolic blood pressure measurements demonstrated a 20-mmHg difference between her arms. Infectious disease, malignancy, and collagen vascular disease workup was unrevealing. Temporal artery and bone marrow biopsies were negative. To exclude FUO of malignancy, (18)FDG PET-CT imaging was performed. The images demonstrated significant (18)FDG uptake (indicating increased metabolic activity) in a circumferential fashion along the aorta and its major braches, including the carotid, subclavian, and common iliac arteries. Contrast-enhanced CT imaging demonstrated wall thickening involving these vessels along with left subclavian vein thrombosis and findings consistent with superficial thrombophlebitis involving the right forearm, wrist, and hand. The combination of laboratory and imaging findings, including the characteristic inflammatory changes involving the large vessel walls as seen on CT, as well as the vessel wall hypermetabolism on FDG PET indicating active inflammation, resulted in the diagnosis of large vessel giant cell arteritis. The patient was treated with high-dose corticosteroids followed by a course of Immuran. Her symptoms resolved and a follow-up FDG PET-CT showed complete resolution of the large vessel hypermetabolism. (18)F-FDG PET-CT can be a useful and noninvasive tool in diagnostic evaluation of FUO by excluding a malignant etiology and providing unexpected information that aids in correct diagnosis.