Pathology. — There are several types of kidney included in this disease, yet in all the changes of structure are essen tially identical, and the variations, when they occur, depend upon the cause and duration of the nephritis.
The large white kidney (without waxy degeneration) may be either normal in size or enlarged, and is pale or yellow ish in color. The surface is smooth and the capsule is easily stripped off. On section the cortex appears broader than normally, and is either yellowish white throughout or may present opaque yel lowish or whitish areas with mattings of red. In some cases the pyramids are congested. The following changes may commonly be observed microscopically: The renal epithelium is swelled, hyaline, granular, or fatty, and is more or less disintegrated or flattened; there is an enlargement of the glomeruli, owing to the growth of the capsule-cells and of the cells covering the capillaries; and, in certain cases, as a result of the con nective-tissue thickening of the capsule, the tuft of capillaries is atrophied. There is some thickening of the arterial walls, and a moderate growth of connective tissue may be noted in patches around the glomeruli and tubules. The latter contain hyaline and granular casts.
The small white kidney (secondary contracted kidney) is, in most instances, probably a later stage of the preceding condition, in which the epithelial degen eration becomes more pronounced, and the connective-tissue growth and the resultant cicatricial contraction become prominent features. The kidneys are about normal in size; owing to a shrink age in the large white kidney, the sur face is slightly granular and the capsule proportionately adherent. In color they are usually grayish or yellowish (pale granular), and there may be a certain amount of red mottling. The consist ency is firmer than that of the large white kidney, and the surface, on sec tion, shows, in the somewhat narrowed cortex, yellowish-white foci of fatty degenerated epithelium; hence the term "small, granular, fatty kidney." Micro scopically we find extensive degeneration and disintegration of the epithelium of the glomernli and convoluted tubules, atrophy of the parenchyma, and a cor responding increase in the interstitial connective tissue. There may be an. as
sociated waxy degeneration.
The large red or variegated kidney of chronic hwmorrhagic nephritis forms a third variety. The kidneys are found, as a rule, enlarged, red, swelled, and con gested-looking or mottled; frequently they are "bumpy," or slightly bosselated. The capsule is slightly adherent to the depressions between the bosses. The sec tion shows congested portions and gray or yellow spots corresponding to the anwmic and fatty-degenerated portions. Red spots, due to small haemorrhage, may also be noticed on both the outer and cut surfaces of the kidney, and small cortical hmmorrhagic areas or striations, brownish-red in color, are distinctive. Microscopically the appearances are those of acute nephritis superadded to those of the large white kidney, and consist of fatty granular degeneration, epithelial proliferation, atrophied capillary tufts, thickened glomeruli capsules, and, in some places, a growth of interstitial fibrous tissue. In either place inflam matory oedema and cellular infiltration of the intertubular tissue may be noted, as well as the dilated tufts of capillaries with surrounding cellular hyperplasia. This variety of chronic nephritis is fre quently seen in inebriates.
Prognosis. — The prognosis is invari ably bad, though life may, in certain cases, be prolonged. Death may occur in severe cases in from three months to a year, from uremia, dropsy, dilatation of the heart, or from other complica tions. Cases of a year's duration seldom recover, and those in which advanced secondary contraction of the kidney may be assumed may be considered hopeless; they often terminate suddenly. Rarely there may be a complete recovery; this occurs particularly in children following an attack of scarlet fever. According to the quantity of urine passed in the twenty-four hours, and the amount and persistence of the albumin, is the prog nosis made, as well as upon the degree of cardiovascular and retinal changes. Relapses may occur in apparently favor able cases, and acute attacks may super vene.