脳動脈硬化の発生, 進展に関する病理学的研究

―小児・若年者例を中心に―

抄録

A topographical view of atherosclerotic lesions and the development of intimal thickening of branching sites, including internal carotid-anterior cerebral-middle cerebral arterial bifurcation and middle cerebral artery-first branch of humans, was studied. A fatty streak was observed in the second decade but its surface involvement did not develop with age. In contrast, a fibrous plaque first appeared in the fourth decade and progressed with age. The fibrous plaque revealed a distinct pattern with a high incidence on the outer walls of daughter vessels with bifurcations. The flow divider was free from fibrous plaques.
In newborns and infants, the focal cellular intima (intimal pad) began to appear on the outer walls of daughter vessels of bifurcations and was replaced by cellulofibrous intimal thickening after one year of age. In similar topographic sites, a heterogeneous, stratified cellulofibrous intimal thickening, consisting of cellular component-rich layer and fibrous component-rich layer occurred in subjects more than 40 years of age. This frequency increased with age. The intima/media ratio increased progressively in successive age groups, and more rapid development was detected in subjects over 30 years old. In cases younger than 40 year-old, foam cells and fatty changes of collagen fibers were not observed in the intima, but LDL deposits were observed. In cases over 40 year-old, foam cells and fatty changes of collagen fibers in the intima were observed with LDL deposition. The cells observed in both the cellular and cellulofibrous intimal thickening demonstrated myosin and vimentin positivity. But the cells in the stratified cellulofibrous intimal thickening were immunohistochemically heterogeneous; some of them did not stain with antibodies to myosin or vimentin, though they were intimal smooth muscle cells.
These findings suggest that the cellular and cellulofibrous intimal thickening, occurring on the outer wall of daughter vessels of bifurcations in young patients, may play an important nascent role as a lesion in atherogenesis.