A 79-year-old patient presented with weight loss, subfebrile body temperature and unclear jaw pain. After ruling out malignant and infectious causes, positron emission tomography-computed tomography (PET-CT) revealed markedly elevated glucose utilization of the large thoracic and upper limb arteries, suggesting systemic vasculitis. Color-coded duplex sonography confirmed thickening of the wall of the external carotid artery consistent with vasculitis. The patient was diagnosed with giant cell arteritis involving the large thoracic arteries and the upper limb arteries but without involvement of the superficial temporal artery. Based on the involvement of the external carotid artery, the jaw pain could be classified as jaw claudication. Clinical and laboratory remission was achieved with systemic glucocorticoids which could subsequently be tapered. The patient is well and asymptomatic 12 months after diagnosis and 2 months without steroids.