Intimal thickening of peripheral pulmonary vein: Analysis of 139 consecutive autopsy cases

Abstract Intimal thickening of the peripheral pulmonary veins collected from 139 autopsy cases (ages ranging from 1 to 96 years) was examined morphologically. The peripheral pulmonary veins were classified as medium-sized veins, small veins, and postcapillary venules. Intimal thickening, graded into four levels from (−) to (+++), increased with age in all three types of the peripheral veins. The severity of intimal thickening was age-dependent. In mediumsized veins, smooth muscle cells were recognized in the intima of all ages, though the amount of collagen fiber in the intima increased with age. In small veins, slight fibrosis and a few smooth muscle cells were seen in the subendothelial regions in autopsy cases up to 20 years of age. Thereafter, collagenous thickening was common. In postcapillary venules, edematous or dense collagenous thickening was a common feature of the intimal thickening in the autopsy cases over 20 years old. In those between 1 and 20 years of age who succumbed to left ventricular failure, intimal thickening was more severe than in those of the same age range in this study. The pathogenesis and the clinical significance of age-associated intimal thickening of the pulmonary veins has not been elucidated yet.