MORPHOPATHOLOGICAL STUDY ON THE EXTIRPATED KIDNEYS IN DIALYZED PATIENTS WITH CHRONIC RENAL FAILURE

Abstract

Effects of dialysis treatment on pathologic processes in the kidney were studied in the patients with chronic renal failure in order to elucidate the relationship between degree of histological alterations of the kidney and dialysis periods.
Forty extirpated kidneys were available from twenty patients who received various terms of dialysis for chronic renal failure.
The cases examined consisted of one case with peritoneal dialysis. seventeen with hemodialysis, and two with both.
The duration of dialysis treatment varied from 9days to 44months and 2weeks.
The underlying renal diseases were chronic glomerulonephritis or secondary contracted kidneys in eighteen cases and malignant nephrosclerosis in the remaining two.
The pathological findings in the kidney of dialyzed patients were as follows.
1) The surface of the kidney of patients who had been treated with long-term periodic dialysis was rather smooth than granular or finely granular as was usually seen in those of non-dialyzed patients with chronic glomerulonephritis.
2) The kidneys significantly lost their weights inversely proportional to the duration of dialysis, and the renal cortex gradually decreased in thickness with dialysis.
3) The completely hyalinized glomeruli increased in number in proportion to the period of dialysis.
4) The morphological changes of the proximal convoluted tubules and their straight portions were most conspicuous among those of the urinary tubules.
In these proximal tubules, atrophy of their epithelium, hyaline thickening of their basement membranes and sclerosis of the interstitial tissues were remarkable in long-term dialyzed cases, and some of them were absorbed by the surrounding interstitial tissues just like hyalinized glomeruli.
5) In Henle's loop, the histological changes of both descending and ascending limbs were more intense in prolonged dialyzed cases than in short-term dialyzed ones. Nevertheless, the degree of atrophy of their epithelium and sclerosis of the interstitial tissues was milder than that of the proximal tubules.
6) The distal convoluted tubules showed stenosis or obliteration of the lumens proportionally to the duration of dialysis, which were associated with little thickening of their basement membranes. The structures appearing as “endocrine kidney” observed in eleven patients were considered to be derived from the distal convoluted tubules.
7) The collecting tubules were almost free from the distinct pathological changes.
8) Intrarenal arterial system clearly showed the various changes.
The interesting findings in the afferent arterioles and the distal segments of the interlobular arteries were swelling and vacuolization of the endothelial cells overlying the intima, and smooth muscle fiber hyperplasia of media.
The characteristic features of the lesions in the interlobular, arcuate and interlobar arteries were: (a) lamellar elastosis in the outer layer and edematous-fibrous or concentric fibrous thickening with an increase of slender elastic fibers in the inner layer of intima, (b) slight to moderate thickening of media and formation of perinuclear vacuole of smooth muscle fiber, and (c) slight fibrosis of adventitial tissues.
Paralleling the term of dialysis, edema in intima was gradually reduced, whereas its fibrous thickening with an increase of delicate elastic fibers became obvious, leading ultimately to obliteration of the lumen.
These findings were also remarkable in long-term dialyzed cases.
9) Deposition of various crystals was observed in the lumen, epithelium and interstitium of the urinary tubules, and in the subendothelial layer of arterioles.
It seems that these variegated morphological changes in the kidneys of dialyzed patients are not entirely newly induced by dialysis, but become manifest in the course of a vicious circle which is established in the long-term dialysis treatment.
The already diseased kidneys become physiolo