The condition designated by these terms was first described by Virchow, and regarded by him as characteristic of Parenchymatous inflammation. The term Parenchymatous degeneration has a similar signification.
It is possible to distinguish a local from a general cloudy swelling. The local form occurs in parenchymatous inflammation, more especially of the kidneys, and is sometimes the most pronounced evidence obtainable post mortem of the existence of that condition. The general form occurs in most febrile diseases and is very characteristic of some. It is met with in the specific fevers, in erysipelas, diphtheria, acute phthisis pulmonalis, etc., and seems to be related in these cases to the high temperature and the altered state of the blood. It also occurs as one of the results of acute poisoning with phosphorus, arsenic, mineral acids. In the general form the lesion is diffused through various organs, but affects especially the liver, kidneys, heart, and voluntary muscles.
In these various cases the condition seems to be due to an irritation of the cells, which are induced to absorb more albumen than they can assimilate. The cells are enlarged, and they are clouded with albuminous granules (see Fig. 41), which obscure the nuclei. The condition implies a qualitative defect in the cells, although quantitatively there is excess. The defect is further shown by the co-existence of a minor degree of fatty degeneration. (See Fig. 41.) The fine fat granules may be obscured by the albuminous granules, but if the albumen be dissolved by adding liquor potassse, or a dilute mineral acid, the fat comes out very prominently.
Fig. 41. - Cloudy swelling of renal epithelium with slight fatty degeneration as seen in the fresh state. A portion of a tubule is shown, and some isolated cells, x 350.
The organs affected have, to the naked eye, a characteristic appearance. They are enlarged, sometimes to a high degree, and have, on section, a bulky appearance, while the tissue has a grey, opaque, dull or • blurred character. In acute fevers the enlargement of the liver and kidneys is sometimes very great.
Virchow, Cellular Pathology, transl. by Chance, also various papers in his Archiv.