Role of PET/CT in the diagnosis of large vessel vasculitis in a patient with systemic inflammatory response syndrome

Abstract

A 57-year-old woman presented with systemic inflammatory response syndrome manifesting as high-grade fever over the past 2 months, unexplained fatigue, malaise, weight loss, night sweats, diffuse nonspecific arthralgias and myalgias. The patient had a history of hypertension for 2 years. The physical examination, with a focus on pulse assessment, bruit auscultation, and inter-arm systolic blood pressure difference, was not suggestive of arterial disease. Laboratory results showed leukocytosis (12,100/μL), elevated erythrocyte sedimentation rate (72 mm/h), and C-reactive protein level (131 mg/L). No clear focus of infection was found. A transthoracic echocardiogram was negative for infective endocarditis. Contrast-enhanced computed tomography of the chest, abdomen, and pelvis did not reveal clinically important abnormalities. With a suspicion of an occult malignancy, the patient underwent whole-body fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) that showed increased 18F-FDG uptake in the thoracic and abdominal aorta expanding to the subclavian, common carotid, and femoral arteries (Figure 1). In the setting of systemic inflammatory response syndrome, we judged these images to be compatible with large vessel vasculitis (LVV). The patient initiated treatment with methylprednisolone and methotrexate, resulting in significant improvement of symptoms and reduction of inflammatory markers.