DISEASES OF THE SKIN. 



INFLAMMATORY CONDITIONS OF THE CUTANEOUS MEMBRANE. 



Inflammatory symptoms of the skin vary according to their intensity, 

 character, or location. The slightest irritation may produce redness, 

 either with or without swelling — this is defined as erythematous inflam- 

 mation; or we may have a formation of circumscribed, solid, firm pro- 

 tuberances, papillae, pustules, boils, or granulations. These are ascribed 

 to exudations originating partially in the papillary body, in the Malpighian 

 membrane, and also in the neighborhood of the follicles. 



The inflammatory exudation may become reabsorbed in certain 

 cases, so that after the acute period of the disease has passed, the epidermis, 

 which has become loosened, is gradually desquamated in the form of 

 scabs or crusts. We also occasionally see a dark pigmentation after the 

 disease has run its course. This originates from the haemoglobin of the 

 extravasated red blood corpuscles. If the inflammatory processes and 

 exudations increase gradually in the cutaneous tissue, we may observe 

 two different results. The inflamed location may become covered with 

 a moist, liquid exudation, or the horny layer of the epidermis is raised up 

 by the fluid, and we may have vesicles which raise the granular layer of 

 the mucous strata, and also the deeper layer of the membrane becomes 

 destroyed in the affected region. In the first case it is covered by the 

 deep layers of the membrane; in the latter case the upper surface of the 

 corium is exposed, having lost its vesicular covering. 



The liquid w^hich fills the small or large vesicles is deficient in cells 

 in the early stages of its formation, and the liquid is clear or slightly 

 yellow. Later it becomes turbid by the addition of leukocytes, and a 

 number of whitish-yellow cells fill the fluid. In some cases it has this 

 appearance from the very onset. When the liquid contained in the 

 vesicle is yellow and filled with cells it is called a pustule. Sooner or 

 later the covering of the pustules becomes ruptured, and the fluid dries 

 up in a yellow, gray, or brown crust, under which the regeneration of the 

 lost epidermic layer goes on rapidly. 



Now and then the inflammatory process shows it Is in the neighbor- 

 hood of a follicle and its sebaceous glands, and we have the formation of 

 a dark red, very sensitive nodule, and finally suppuration of the same 

 membrane and its adjacent tissues. As a consequence of this we find 



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