This section is from the book "A Treatise On The Materia Medica And Therapeutics Of The Skin", by Henry G. Piffard. Also available from Amazon: A Treatise On The Materia Medica And Therapeutics Of The Skin.
Eczema is a non-contagious affection of the skin, of multiple lesion and of constitutional origin. As all cases of eczema are not alike either in their appearance or in their course, we are of necessity obliged to acknowledge several varieties, and to describe them separately, if a clear conception of this polymorphous disease is to be obtained. "The task is not an easy one, as there is no one form that may be regarded as strictly typical, and of which the others are but varieties, and yet there are certain features common to all or most all cases, that the experienced eye will detect at the clinic, but which are exceedingly difficult to transfer to paper. In this most common of all cutaneous diseases, we are forced to recognize differences depending on the degree of inflammatory action present, on the duration and the character of the lesion, and on the location that is affected, as all of these greatly modify the appearances presented, the prognosis, and the details of treatment.
An eczema may commence abruptly and with evidence of intense inflammation, or gradually, and without much local reaction, or any constitutional disturbance. In other words, it may be, from the beginning either acute or subacute. It may run its course in a few weeks, or it may persist for months or years, that is, it may be acute or chronic. Or again, the affection may exhibit features indicating an acute local action and yet persist for a very long time in this condition; in other words, it may be at the same time acute as to its degree, and chronic as to its duration. We will commence with the acute and afterward describe the chronic forms.
An acute eczema, if the eruption is at all extensive, may be preceded by febrile action, usually mild, rarely severe. This, if present, is succeeded by the appearance of a reddened patch of varying size, due to acute capillary hyperemia. This is accompanied with local elevation of temperature, and a sensation of burning or itching. In a day or two, or in a few hours, this reddened patch becomes the seat of the special lesions of eczema. These are either vesicles, pustules, papules, fissures, or a condition that I am in the habit of terming primitive exfoliation. The occurrence of the lesions is due to the presence of an exudation which, leaving the vessels, seeks to make its way to the surface. This exudation may be serous, purulent, or plastic. In the latter case it is retained within the tissues of the skin, and tends to accumulate at numerous isolated points beneath the epidermis, and gives rise to papules. If, however, the exudation is serous or purulent, it penetrates and traverses the stratum Malpighii, and appears beneath the stratum corneum. Having arrived here, and urged outward by the pressure of continued exudation behind, it either lifts up little portions of the stratum corneum, forming vesicles or pustules, or else produces linear cuptures of this stratum, and passes outward through the little clefts or fissures thus formed; or, lastly, and I believe most frequently, simply loosens the attachments of the horny cells, and sweeps them away in minute and almost imperceptible scales. Formerly the only admitted primitive lesion was the vesicular, the pustular form being regarded as a distinct disease, to which the name of Impetigo was given, and the papular form, also believed to be distinct, was termed Lichen.
The vesicles of eczema are usually quite small, except on the palmar and plantar surfaces, seldom being larger than pin-heads, and closely aggregated. They rarely retain their integrity for more than twenty-four or forty-eight hours, being broken by friction from the clothes or the patient's rubbing and scratching, or if this does not occur, they soon rupture spontaneously in consequence of the pressure of the exuded fluid. On breaking they give issue to a colorless and transparent fluid which, unless absorbed by the clothing, loses a portion of its water by evaporation, and dries into yellowish or amber-colored, sticky crusts, varying in thickness with the amount of exudation. If the fluid has been absorbed by the under-garments they are found to be spotted, though not discolored, and by coagulation of the plastic exudation in the meshes. This Stiffening of the linen is a peculiar and marked characteristic of the eczematous exudation. If the crusts be removed we find a moist and reddened surface, from which fresh exudation may almost be seen to ooze.
This surface at first sight seems to be ulcerated, but closer inspection simply shows a condition of extremely superficial erosion, due to the shedding of the stratum corneum, the stratum Malpighii being still intact. The redness is not absolutely uniform, but more frequently punctate, and examination with a lens of high power will show the points of moat intense congestion to correspond to the situation of the pipillae. The exudation is not pure serum, but contains a little fibrin and a few leucocytes. If the surface be wiped dry it will remain so but a short time only, and will soon be again covered with exudation that on drying will form fresh crusts. These will remain attached until removed me-chanically, or until they have acquired such a thickness that they drop off spontaneously.
The preliminary hyperemia and the vesicle formation may be con-veniently termed the first stage. This is always of brief duration; not so, however, the second stage or period of exudation and crusting. This may last almost indefinitely; at least, it is impossible to say at the beginning how long it will continue. After a time, however, the exudation diminishes, the crusts become thinner, and the surface under them dry, and, gradually, attempts are made at the re-formation of a new, horny epithelium. The aspect of the eruption changes and the surface becomes scaly, the scales being composed of new epidermis. The newly formed cells, however, do not possess normal viability, and are quickly shed and replaced by others, exhibiting a somewhat closer approximation to the normal type. As the patch gradually tends toward recovery the desquamation lessens, and the white scales become firm and more adherent, until, at last, the corium, rete, and stratum corneum recover their normal condition and no trace of the eruption remains.