Fatty Necroses

Fatty Necroses, more correctly necroses of fatty tissue (German Fettgewebsnekrosen), represent focal death of adipose tissue, occurring most frequently in the region of the pancreas and in its immediate vicinity, less frequently among retroperitoneal fatty tissue in parts of the abdomen distant from the pancreas, among the fat of the omentum [see separate table (pp. 103-104), figure 2], mesenteries; rarely - in the fatty tissue of the mediastinum, fatty covering of the epicardium, fatty layer under the parietal pleura, even more rarely - in subcutaneous fatty tissue, in bone marrow. In most cases, we are dealing with multiple foci of F.N. of small size, which are concentrated mainly in the region of the pancreas and spread from it, as if from a center, to one side or another to some distance. The foci of F.N. range in size from a pinhead to a pea, rarely larger, and appear on the light yellow, translucent background of normal fatty tissue as dull white or yellowish-white spots (in the presence of jaundice - yellow in color), of firm consistency, resembling stearin (French "taches de bougies"), less frequently - of liquid consistency. The Benda reaction, consisting in fixing the tissue for 24 hours at 37° in "Weigert's copper acetate-acetic acid mordant for neuroglia" with the addition of 10% formalin, stains F.N. green. Under the microscope, in the foci of F.N., the structure of fatty tissue is visible, but nuclei are absent in it, and the fat cells are found to contain lumpy, clotted masses, insoluble in alcohol and staining on hematoxylin-eosin preparations partly pink, partly violet; among these masses, the presence of fatty acid crystals is also sometimes noticeable. As established microchemically (Langerhans and others), this microscopic picture is explained by the splitting of neutral fat in dead fat cells with the formation of fatty acids and fatty acid soaps; the lumpy masses giving a violet color with hematoxylin consist mainly of fatty acid lime. In later periods, an inflammatory reaction is found around the foci of F.N., which initially manifests itself in the appearance here of some wandering cells, phagocytosing the products of fat breakdown (Reitmann's "steatoclasts"), later - in the development of granulation tissue, usually with giant cells, surrounding and penetrating the dead focus. As a result, in place of the F.N. focus, there may be either a scar or a cyst, surrounded by a connective tissue capsule, or encapsulated lime concretions. In more rare cases, purulent melting of the F.N. focus occurs, which most often takes place when Bact. coli communis penetrates the focus; the developing abscess usually ruptures into the abdominal cavity, causing local or general peritonitis. The basis of the pathogenesis of F.N. in the region of the pancreas and generally in the abdominal cavity is the action on fatty tissue of steapsin, which is a component of pancreatic juice; as established by experiments and patho-anatomical observations, with disturbances in the secretion of pancreatic juice of the most diverse origins, the latter can diffuse into the surrounding tissue, on which it acts in a necrotizing manner. The circumstance that in such cases, in the presence of fat splitting, the action of another enzyme of pancreatic juice - trypsin - is usually absent, is explained by the fact that the fat proferment is activated much more easily and quickly than protrypsin. However, in some cases, along with F.N., necroses and pictures of digestion of the glandular tissue of the pancreas and its connective tissue stroma are observed, which is due to the action of trypsin. Steapsin of diffusing pancreatic juice splits the fat of fat cells and thereby kills them; all subsequent changes are connected with further stages of the process of fat splitting and the reaction of the surrounding tissue (see above).- Whereas most foci of F.N. in the abdominal cavity, as well as probably in the chest cavity (mediastinum, epicard) can be explained by the above-mentioned diffusion of pancreatic juice,- for the explanation of some foci of F.N., especially those located more remotely, for example in subcutaneous fatty tissue, it is permissible to assume embolism with cells of the pancreas (when its tissue is damaged).- F.N. of the above-mentioned pancreatic origin are observed very often with the most diverse lesions of the pancreas, both severe and mild, with various injuries to the gland, its inflammations, neoplasms (both of the gland and of the Vaterian papilla of the duodenum). Further - with compressions of the Wirsungian duct by tumors, their metastases, scars, inflammatory foci; with obstruction of the duct not only by a stone, but also by mucus, e.g., when the Wirsungian duct is involved in the catarrhal inflammation of the duodenum or of the bile duct; finally, when bile enters the Wirsungian duct due to spasms of the duct and increased mucus secretion occurring at this time. F.N. observed near the pancreas sometimes without any of the above-mentioned disturbances in its condition, are explained by a perversion in the direction of its secretion during agony. F.N. of the pancreas and abdominal cavity are most commonly found in obese subjects, in alcoholics, in persons suffering from gallstones. Usually representing only a complication of one or another ailment, F.N. do not have a great influence on the course of the main disease; only in cases of extensive spread of F.N., the inflammatory reaction around their foci and the absorption of toxic products of fat tissue breakdown can manifest themselves with corresponding symptoms and worsening of the disease.- Besides the F.N. of pancreatic origin described above, focal deaths of adipose tissue are observed, having no relation to the pancreas. These include lobular necroses of fatty tissue of embolic origin (e.g., in sepsis lenta), necroses of subcutaneous fatty tissue with various injuries to it and inflammations in it, with spasms of vessels from prolonged cooling, finally the so-called spontaneous F.N., arising due to angioneurotic disorders, sometimes from intoxicating influences. In all such fatty necroses, the fat of fat cells, under the influence of the enzyme lipase contained in them, undergoes splitting in the same way, and an inflammatory reaction develops around the foci of fatty necroses; this gives pictures, in general, similar to those mentioned above in relation to pancreatic fatty necroses.