<prompt> All are true about Giant cell arteritis except -Involves large to small sized arteriesGranulomatous inflammationMost commonly involved artery is abdominal aortaSegmental nature of the involvement  <response>: It is the most common form of systemic vasculitis in adults, is an acute and chronic, often granulomatous, inflammation of arteries of large to small size.It affects principally the arteries in the head-especially the temporal arteries but also the vertebral and ophthalmic arteries and the aorta, where it may cause thoracic aortic aneurysm 