1 Initial, fatty streak, and intermediate lesions were defined in the second. Normal arterial intima, including atherosclerosis-prone regions, was defined in the first report. The objective of the series was to provide a practical classification of human atherosclerotic lesions based on their histological composition and structure. This report is the third and last in a series. Some type V lesions are largely calcified (type Vb), and some consist mainly of fibrous connective tissue and little or no accumulated lipid or calcium (type Vc). Beginning around the fourth decade of life, lesions that usually have a lipid core may also contain thick layers of fibrous connective tissue (type V lesion) and/or fissure, hematoma, and thrombus (type VI lesion). This extracellular lipid is the immediate precursor of the larger, confluent, and more disruptive core of extracellular lipid that characterizes type IV lesions. In addition to the lipid-laden cells of type II, type III lesions contain scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. Type III is the intermediate stage between type II and type IV ( atheroma, a lesion that is potentially symptom-producing). Type II lesions consist primarily of layers of macrophage foam cells and lipid-laden smooth muscle cells and include lesions grossly designated as fatty streaks. (Adaptive thickenings, which are present at constant locations in everyone from birth, do not obstruct the lumen and represent adaptations to local mechanical forces). As in subsequent lesion types, the changes are more marked in locations of arteries with adaptive intimal thickening. The initial (type I) lesion contains enough atherogenic lipoprotein to elicit an increase in macrophages and formation of scattered macrophage foam cells. In the histological classification, lesions are designated by Roman numerals, which indicate the usual sequence of lesion progression. The Committee on Vascular Lesions also attempted to correlate the appearance of lesions noted in clinical imaging studies with histological lesion types and corresponding clinical syndromes. These, with the earlier definitions of precursor lesions, led to the histological classification of human atherosclerotic lesions found in the second part of this report. This report describes the characteristic components and pathogenic mechanisms of the various advanced atherosclerotic lesions. Customer Service and Ordering InformationĪbstract This report is the continuation of two earlier reports that defined human arterial intima and precursors of advanced atherosclerotic lesions in humans.Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).

Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).

Ypsilon minus by Herbert W. Franke