[An update on giant cell arteritis]

Giant cell arteritis (GCA) is a primary granulomatous systemic vasculitis involving the aorta and its main branches that affects people aged over 50 years with a genetic predisposition. Its main phenotypes are cranial and extracranial involvement, with or without symptoms of polymyalgia rheumatica. These phenotypes can overlap. The extracranial form can be oligosymptomatic and must be sought directly. The main complications of the disease are ischemia of essential territories such as the optic nerve or cerebral circulation, and aneurysmal dilations of the aorta and its large branches. Clinicians must be aware of all the presentation forms of the disease, to start a timely treatment and avoid potentially serious or fatal consequences. To date, the diagnosis of GCA is based on clinical and pathological criteria, with the temporal artery biopsy as the "gold standard" for diagnosis, although its sensitivity is variable. This can lead to an underdiagnosis in patients with negative biopsies or predominant extra-cranial symptoms. The emergence of new and valuable imaging tools substantially improved the timely diagnosis, mainly in subclinical and oligosymptomatic forms. Among them we highlight ultrasonography of the temporal and axillary arteries, Computed Tomography Angiography, Magnetic Resonance Angiography, and PET-CT. These imaging techniques are complementary, and their use is highly recommended. GCA treatment is based on steroidal therapy, often associated with a corticosteroid-sparing immunosuppressive agent. The follow-up is eminently clinical.