Giant Cell Arteritis

Giant cell arteritis (GCA) is the most common form of systemic vasculitis in adults. It predominantly affects the aorta and its major branches, including the temporal arteries. It mainly affects individuals over 50 years of age, with a higher incidence in whites and women. The worldwide pooled annual incidence is 10 per 100,000, with variations between populations: highest incidence in Scandinavians and Americans, lowest in Africans and East Asians. The estimated prevalence is 51.74 per 100,000 in people over 50 years of age. GCA is thought to be triggered by T cells responding to an unknown antigen. This leads to immune cell infiltration of affected arteries and cytokine production with local and systemic effects. Symptoms can be divided into four subsets: cranial arteritis, extracranial arteritis, systemic symptoms, and polymyalgia rheumatica. Common symptoms include new-onset temporal headache and jaw claudication. Serious complications can include blindness and cerebrovascular accidents. High erythrocyte sedimentation rate, elevated C-reactive protein, inflammatory anemia and thrombocytosis are common biomarkers associated with GCA. There are no specific diagnostic criteria for GCA. The American College of Rheumatology (ACR) and European Alliance of Associations for Rheumatology (EULAR) published updated classification criteria in 2022. These criteria are for research and not for clinical diagnosis. The criteria aim to standardize research cohorts, but are not suitable for clinical diagnosis. Diagnosis should be considered based on the basis of clinical manifestations and laboratory findings. No single feature has a high predictive value for GCA. The pretest probability should guide further investigations. Temporal artery biopsy (TAB) has historically been considered the gold standard for cranial GCA. Sensitivity varies due to factors such as sampling quality and extracranial vasculitis. Imaging techniques such as ultrasound (US), magnetic resonance imaging (MRI), and fluorodeoxyglucose-positron emission tomography (FDG-PET) have become relevant for diagnosis. US is cost-effective and non-invasive, but operator-dependent. MRI and FDG-PET may be alternatives in certain cases. GCA is a medical emergency and treatment should not be delayed. Glucocorticoids are the mainstay of treatment. Tocilizumab or methotrexate can be used in combination with glucocorticoids. Aspirin may be considered to prevent ischemic events.