Erythematous inflammation, as has been said, is an inflammation of the outermost layer of skin, which contains the papillae; and it includes not only the slight inflammation produced by external agents, such as the heat of the sun, fire, cold, irritating plasters, trifling injuries, the stings of insects, etc, but also spontaneous inflammations of exanthematous nature, which are essentially connected with other morbid processes such as the various erythemata, erysipelas, scarlatina, measles, intertrigo, etc.

Erythematous inflammations usually run an acute course, but several of them are apt to recur, and to become habitual.

The following are the anatomical characters of the disease. The redness is for the most part bright and uniform, but sometimes it is irregular, presenting here and there various forms and outlines of a deeper hue, and very frequently it has a shade of yellow: the color gradually diminishes towards the border of the inflammation, and passes imperceptibly into that of health: it disappears upon pressure, and quickly returns when the pressure is remitted. There is mostly but trifling swelling, such as can be perceived only by the touch, and at the border of the diseased spot. The exudation is determined by the intensity of the process: sometimes there is none; sometimes a watery fluid, effused slowly or very rapidly, raises the epidermis in small and scattered, or in confluent, vesicles. The under surface of the skin is reddened, has a granular or uneven glandlike appearance, and is covered more or less distinctly with a grayish-white, soft, gelatinous, plastic exudation, which is sometimes perforated and cribriform, and sometimes is reticulated on the surface next the skin. If the inflammation still increase after this product is deposited, the redness becomes darker and the exudation reddish, milky, and at last purulent.

1 [Vide Behrens' Dissert. Epistol. de Affectionibus a Comestis Mytulis. Hanover, 1735. p. 3 - Ed ].

After death the redness has generally disappeared, but the swelling is still perceptible; the epidermis is either easily separable or actually separated, and the surface of the cutis is moist, and covered with a viscid and more or less puriform exudation. The redness is seen on a transverse section to be confined to the outermost thin layer of the cutis; the deeper layer is pale, and is somewhat infiltrated only when the inflammation is intense; the subcutaneous cellular tissue is then in like manner slightly infiltrated.

Erythematous inflammation generally terminates by resolution, the epidermis peeling off one or more times, according to the severity of the inflammation, in the form of a mealy powder, or a bran-like scurf, or of larger scales and laminae, until the skin, covered with a new thin epidermis, looks smooth and shining and of its healthy color.