IMPETIGO. 479 



CHAPTER VIII. 



IMPETIGO DIFFUSE STJPEEFICIAL DERMATITIS, WITH FORMATION OF 

 SMALL PUSTULES. 



ETIOLOGY. In impetigo, as in eczema, a serous exudation is se- 

 creted upon the surface of the corium, but at the same time young cells 

 form in great abundance and are mingled with the serum. Hence, the 

 contents of the vesicles which arise in impetiginous dermatitis are not 

 limpid and transparent, like those of eczema, but turbid and yellowish, 

 and, upon rupture of their epidermis, a purulent liquid runs out from 

 them, which afterward dries up into yellowish or greenish crusts. 



As the serum in the vesicles of eczema also contains a few young 

 cells, and since in eczema impetiginosum the contents of some of the 

 vesicles are yellow and puruloid, owing to the copious admixture of 

 young cells, it is plain that no distinct boundary line can be drawn be- 

 tween eczema and impetigo ; and that there are intermediate forms to 

 which either name might be applied with equal propriety. This is 

 especially the case in the moist eruption upon the scalp of children 

 which sometimes bears the title of eczema capitis or faciei, and some- 

 times that of impetigo or porrigo faciei or capitis. 



The first cause of impetigo which we shall mention is the direct ac- 

 tion of irritants upon the skin. The more delicate the skin, so much 

 the more easily do even slight irritants cause exudation, and prolifera- 

 tion of cells upon its surface. In some persons, the application of a pitch- 

 plaster or of a poultice is sufficient to provoke an eruption of impeti- 

 ginous pustules. This " vulnerability " of the skin is most common 

 among people with a thin epidermis and clear complexion ; but, above 

 all, among scrofulous individuals. Among the latter, indeed, impetigo 

 often appears without any appreciable irritation of the skin, and, to- 

 gether with chronic catarrh, and enlargement of the lymphatic glands, 

 is one of the most decided symptoms of scrofula. Finally, impetigo at- 

 tacks children without perceptible irritation of the skin, scrofulous 

 diathesis, or other assignable cause. In such cases, which are not at 

 all rare, it is generally assumed that the food is too nutritious, that the 

 mother's milk is too rich, or that the eruption has been caused by the 

 presence of an " acrid " material in the blood. No sound reasons can 

 be advanced in support of such an idea. 



SYMPTOMS AND COURSE. The inflammation of the papilla, from 

 which the exudation proceeds, is accompanied by a sense of itching, 

 and by a desire to scratch. These subjective phenomena, and the 

 objective ones, of small acuminated pustules (psydracia) upon a red- 

 uened base, and of yellow scabs, are about the only symptoms pre- 



