It will be seen that the name of " depurative infiltration" is given to the same form of kidney disease which is called by others waxy or amyloid.
Blebs describes : I. D!:ffuse Granular Degeneration of the Epithelium.—This condi tion is found by itself, and in connection with lesions in the intersti tial tissue. By itself, it occurs with pynmia, phthisis, rheumatism, typhoid and typhus fevers, the malarial fevers, the acute exanthemata, extensive burns, poisoning with phosphorus and the mineral acids. During life the urine may contain granular casts and albumin. The kidney is somewhat enlarged, the cortex grayish-yellow, the pyramids bluish-red. There may be little extravasations of blood in the con voluted tubes. The epithelium of the tubes is granular and may distend them. The tubes may contain casts. These changes are most frequent in the convoluted tubes, but are sometimes con fined to the straight tubes of the pyramids. The entire process is a degener ative and not an inflammatory one.
2. Cyanotic Induration of the Kidneys.—This condition is produced by any long-continued obstruction to the escape of venous blood from the kidneys, most frequently by heart disease. The kidneys are in creased in size, the surface is smooth, the capsule not adherent. The organ is hard, the cortex and pyramids are congested and of a dark red color. The epithelium of the tubes is not altered. The interstitial tissue is harder, but not increased in amount. The continued conges tion may, after a time, produce further changes. The epithelium of the convoluted tubes may undergo granular degeneration, and the cortex becomes paler. Or there may be an increase of interstitial tissue, and the surface becomes nodular.
3. Interstitial Nephritis. —This has two stages : (a) That of cell-in filtration; (b) That of atrophy.
(a) The Stage of Cellular Infiltration of the Interstitial Connec tive Tissue.—The kidney is increased in size. The surface is smooth, the capsule not adherent. The cortex is of a whitish or yel lowish color, the pyramids are red. In the cortex the tissue between the tubes is everywhere increased from two to four fold. This increase is clue to the presence of lymphatic elements and of clear serum. There
is at first an exudation of lymphatic fluid, which dilates the lymphatic vessels of the interstitial tissue, and is accompanied by an emigration of white blood-globules, which finally fill all the spaces in the inter stitial tissue. The epithelium of the convoluted tubes undergoes granular degeneration iu consequence of its disturbed nutrition. The increased pressure of blood causes an exudation of the elements of the blood from the Malpighian tufts, namely, fibrinogenic material which coagulates in the tubes, albumin, and red blood-globules. The lymphatic cells perforate the basement membrane of the tubes, and become adherent to the fibrinous cysts.
(b) The Stage of Atrophy.—The preceding stage may terminate in resolution and recovery. If it does not, it is succeeded either by a hyperplasia of connective tissue or by granular atrophy.
If there is a hyperplasia of connective tissue, the kidneys are of normal size, or slightly atrophied. The capsule is somewhat adhe rent. The cortex is whitish, yellowish, or mottled. The pyramids are congested. There is a uniform increase of connective tissue be tween the tubes. The tubes are unaltered or somewhat narrowed.
Granular atrophy is more common. The kidney is atrophied. The capsule is very adherent. The surface is uneven and nodular.
The change of the lymphatic cells into Connective tissue is accompa nied by fatty degeneration of the cells. In the atrophied spots the tubes and glomeruli become impervious. The tubes contain hyaline casts. The basement membrane of the atrophied tubes becomes thick and fibrous. The glomeruli are atrophied, their capsules thickened, their vessels obliterated. The larger arteries are thickened.
Glomerulo-nephritis.—Klebs gives this name to a form of disease which he has observed in scarlatina cases. The kidneys arc of me dium size, the capsule is not adherent, the surface smooth, the paren chyma congested. There are no changes except in the glomeruli. These appear as opaque, white points. On minute examination, it is found that there are large numbers of small, rounded cells about the loops of the Malpighian tuft, while the epithelium of the capsule is unaltered.