[Diagnosis of giant cell arteritis].

DIAGNOSIS OF GIANT CELL ARTERITIS. The diagnosis of giant cell arteritis (GCA) must be made promptly in order to initiate appropriate treatment aimed at relieving symptoms and avoiding ischemic complications, particularly visual ones. The diagnosis of GCA is based on the occurrence, in a patient over 50, of clinical signs of GCA, primarily recent headaches, or polymyalgia rheumatica, as «evidence» of large-vessel vasculitis, which is provided by histological analysis of an arterial fragment, usually the temporal artery, or by imaging of the cephalic arteries, the aorta and/ or its main branches by Doppler US scan, angio-CT, 18fluorodeoxyglucose PET scan or more rarely by MRI angiography. In addition, in more than 95% of cases, patients have an elevation in markers of inflammatory syndrome. This is less marked in the case of visual or neurological ischemic complications. Two main GCA phenotypes can be distinguished: on the one hand, cephalic GCA, in which cephalic vessel involvement predominates and which identifies patients at the greatest risk of ischemic complications; on the other hand, extracephalic GCA concerns younger patients with a lower ischemic risk but with more aortic complications and more frequent relapses. The establishment «fast track» type structures in specialized centers allows for rapid management in order to identify patients to be treated in order to avoid ischemic complications and to quickly perform the necessary examinations to confirm the diagnosis and ensure that the patient receives appropriate management.