What are giant cell arteritis gca and polymyalgia rheumatic pmr this condition causes inflammation of the arteries in the arms upper body and neck arteries are blood vessels that carry blood from the heart to the rest of the body arteritis is a condition in which the arteries become inflamed swollen. Giant cell arteritis and polymyalgia rheumatica are diagnosed in different ways because it is an autoimmune disease some symptoms are also similar to other immune disorders your rheumy will advise you to have blood tests to accurately diagnose your health issue giant cell arteritis is detected through biopsy of the temporal artery. Polymyalgia rheumatica and giant cell arteritis are closely related disorders that affect people of middle age and older they frequently occur together both are syndromes of unknown cause but genetic and environmental factors might have a role in their pathogenesis. Giant cell arteritis gca along with polymyalgia rheumatica pmr are autoimmune disorders involving the medium and large arteries which have muscular walls and vasa vasorum in their adventitial