Atlas of Diagnostic Pathology (6) : Cardiovascular System 2: Blood Vessel-Arteriosclerosis, Aneurysm, Marfan\u27s Syndrome

Arteriosclerosis is a general term for atherosclerosis, Monckeberg arteriosclerosis and arteriolosclerosis, all of which involve sclerosis of blood vessels. Atherosclerosis is a progressive disease characterized by the formation of atheromas and fibrous plaques in the intima. Plaques, which may be stable or unstable, are complicated by ulceration, hemorrhage and calcification. Unstable plaques are more cellular and tend to hemorrhage. The pathogenesis of atherosclerosis is still uncertain, but reaction to injury formulation theory is widely accepted. Monckeberg arteriosclerosis is characterized by medial calcification, which does not obstruct arterial flow. Arteriolosclerosis is characterized by hyaline thickening or proliferative change in small arteries, which are usually associated with hypertension and diabetes mellitus. Aneurysms are abnormal dilatations of blood vessels, and are of several types. Berry aneurysms are small saccular lesions most often seen in the circle of Willis, but are unrelated to atherosclerosis. A dissecting aneurysm is a longitudinal intraluminal tear, usually in the walls of the ascending aorta. Cystic medial necrosis is a major cause of dissection, which is associated with Marfan syndrome. Connective tissue defects are typical of Marfan\u27s syndrome. Vasculitis is classified by vessel size. Necrotizing arthritis is usually mediated by immune mechanisms, particularly immune complex depositions