Definition:

Giant cell arteritis (GCA), also known as temporal arteritis, is a chronic and polygenic immune-mediated disease of unknown etiology. It is the most common form of vasculitis in individuals over the age of 50 in Western countries. It is characterized by inflammatory damage of the aorta and/or aortic branches, particularly the temporal artery, which can lead to severe complications such as blindness or cerebrovascular disorders. GCA is twice as common in women. It is frequently associated with polymyalgia rheumatica. Laboratory tests usually reveal high erythrocyte sedimentation rate (ESR), elevated levels of C-reactive protein (CRP) and other acute phase proteins, anemia of chronic disease, and thrombocytosis. Genetic association studies have described several genes that are associated with predisposition to GCA, including genes of immune-inflammatory pathways and genes of the HLA class I and II regions. The HLA-DRB1*04 alleles seem to be the most consistently associated genetic risk factors for GCA. Outside the HLA region, the most significant loci included PTPN22. Glucocorticoids are currently the mainstay of treatment for GCA but are associated with frequent adverse events. Tocilizumab, a humanised antihuman IL-6 receptor antibody, has been used successfully in several reports as a treatment of GCA.