Giant cell arteritis.

Giant cell arteritis (GCA) is an immune-mediated chronic vasculitis of large- and medium-sized vessels usually occurring in White individuals aged over 50 years, in Western countries. The pathological hallmark of GCA is granulomatous inflammation of the involved vessels. Headache of new-onset is the most common clinical manifestation, and permanent vision loss is the most feared complication of GCA. The level of clinical suspicion for GCA should be based upon patient age, clinical symptoms, laboratory evaluation, and imaging findings. However, the diagnostic gold standard is achieved by histologic confirmation by temporal artery biopsy. Corticosteroids remain the only proven treatment for GCA and the prognosis for visual recovery is poor.