Abnormal aortic morphology Aortitis The term aortitis encompasses inflammatory changes to the aortic wall from varying etiologies that are associated with certain specific histopathological lesions. The inflammatory response may be limited to the aortic wall or accompanied by changes directly adjacent to the vessel (e.g. retroperitoneal fibrosis) or other vessels (e.g., giant cell arteritis). A distinction is made between infectious and non-infectious aortitis. Takayasu arteritis and giant cell arteritis are the most common causes of non-infectious aortitis. Aortitis refers to inflammatory changes to the wall of the aorta and incorporates both infectious and non-infectious etiologies.