A system of practical medicine. By American authors. Vol. 1

by Unknown

The clinical importance of fatty metamorphosis requires consideration in connection with the description of the diseases in which its occurrence is a constant feature. As the presence of fat in cells is not necessarily pathological, so an interference with the function of the cell is not invariably implied by its presence. When its existence is suggestive of a local destruction of albuminates, a diminution of cell-activity is a necessary consequence. Such diminished activity must produce different results as the cells are those of muscles, of vessels, or of glandular organs.

Even if fat is found in cells under conditions favoring such a suggestion, it does not follow that the destruction of the cell must result. Not only is it possible that the fat may be reserved for eventual oxidation, and its place in the protoplasm be filled by normal constituents, but it is also possible that the fat may be eliminated, as such, from the body. The latter event is made apparent by the experiments of numerous observers referred to by Cohnheim, who have found free fat in the urine after its introduction into the venous current.

Cheesy Metamorphosis, Cheesy Degeneration, Caseation.

Virchow introduced the term cheesy metamorphosis, tyrosis, to designate the process resulting in the incomplete absorption of pus and the production of apparently similar changes in certain other occasional constituents of the body. The characteristic cheesy appearances were regarded as due to the inspissation of the material concerned, in consequence of the absorption of its fluid. With this inspissation there was frequently associated a partial fatty degeneration, and the cheesy matter represented dead material, which might undergo further changes, of which softening and calcification were the more important.

Inflammatory products, as pus and fibrin, were especially prone to become thus transformed, as well as other relatively transitory materials of new formation—viz. tubercle and parts of various tumors. The type of the cheesy metamorphosis was found in the enlarged lymphatic glands, commonly called scrofulous.

The importance of a clear understanding of the cheesy metamorphosis is now a matter of history. It is merely necessary to allude to the fact that these cheesy products were formerly regarded as indicative of the presence of tubercle, and were the tubercles. Tuberculization and the cheesy condition were synonymous terms, and their indiscriminate use led to much confusion with reference to the nature of tubercle.

Quite recently Weigert³² has called attention to the conditions present in necrosis resulting from the intermediate stoppage of the blood-current in a part. The effect is manifested, under favoring circumstances, by a cheesy appearance of the affected region, to which the terms decolorized hemorrhagic infarction, anæmic or ischæmic necrosis, have been applied. Weigert lays stress upon the existence of a coagulation of the protoplasm of the cells, with an early disappearance of the nuclei, as the essential feature of this form of necrosis, the conditions present being regarded as analogous to those met with in the coagulation of the blood. The term coagulative necrosis has consequently been introduced by Cohnheim to represent the process first fully described in detail by Weigert. The optical and physical properties of the ischæmic or coagulative necroses of tissue are often manifested as cheesy appearances, although the term coagulative necrosis includes conditions which do not present a suggestion of cheese. It is thus apparent that cheesy appearances may result in two ways: 1, by the inspissation of material in a state of partial fatty degeneration; 2, by a coagulation of the constituents of cells whose blood-supply is suddenly and completely cut off. In the more restricted sense these caseous appearances are regarded as indicative of a cheesy metamorphosis which arises by the former of these methods. Cheesy appearances, on the contrary, dependent upon the sudden death of a part, indicate an ischæmic or coagulative necrosis.

³² Virchow's Archiv, 1880, lxxix. 87.

Whatever may be the origin of the cheesy condition, the material presenting this appearance is liable to further changes, known as softening and calcification. The former event results from the soaking of the dead part with liquid, in consequence of which a detritus results. The softening usually begins at the oldest part of the cheesy mass, and advances toward the periphery. The sanatory evacuation of the emulsive detritus is permitted when a surface continuous with that of the external surface of the body is reached, as instanced by the escape of softened cheesy material from the lungs through a bronchus. The possibility of the complete removal of the dead mass is thus at hand, and an eventual obliteration of the resulting cavity may take place by an adhesive inflammation of its walls.

The complete absorption of the cheesy material of an ischæmic necrosis may occur by the extension into the latter of a granulation-tissue from the periphery. Whenever cheesy appearances are found on surfaces, as the degenerated tubercles of mucous membranes or the circumscribed necroses in diphtheritic inflammation or in typhoid fever, healing may be accomplished by their detachment as sloughs, a clean ulcer being left. Cheesy material is frequently encapsulated—i.e. imbedded in a layer of dense connective tissue, a condition which indicates a local cessation of the process through which the cheesy appearances arose. The same may be said of the infiltration of the cheesy mass with earthy salts—calcification—an event which will again be referred to in connection with the consideration of the general subject.