Under the head of local dermal inflammations we include those diseases which partake essentially of the nature of local diseases, and are characterized by inflammation, as the primary and the essential phenomenon. By inflammation we understand not merely hyperaemia, with engorgements of the affected parts by blood, so that the parts are swollen and red and hot, not only hyperaemia, with stasis in the vessels and serous effusion in addition; but also an increased activity in the tissues themselves outside the vessels, and the formation of new products, or “inflammatory exudation,” to use a commonly employed term.
The character and source of these new products are important items in this matter of inflammation. As regards the character of the new products, its typical features, and ultimate destination in marked cases are those of pus. Pus, in fact, is the highest grade of inflammatory products, but pus is not necessarily formed, and it is held that the new products may give rise to the production of a tissue-like connective tissue. Pus is derived from two sources-namely, from white blood cells, and also from connective-tissue corpuscle. There are three leading changes observed in inflammatory exudation-resolution, organization, and suppuration.
The local inflammations we are about to consider are generally characterized by hyperaemia and the presence of inflammatory infiltration. They are the erythemata; eczema, or catarrhal inflammation; that form which commences as serous catarrh of the papillary layer, and is followed by the outpouring of sero-purulent discharge, as in catarrh of the mucous membrane; plastic or papular inflammation, in which the inflammation is characterized as much by the absence of serous as by the deposit of fibrinous exudation: suppurative inflammation; and lastly, hyperaemia, accompanied by excessive formation of epithelial and certain cell growths in the papillary layer, conveniently termed squamous inflammation, as in psoriasis.
Two of these groups or classes might be separated from inflammation perhaps, and dealt with as hyperaemias solely, and these are the first and the last of the above named. In the former there is hyperaemia and serous exudation, as in erythema; but what is the important things to notice in relation to the point under discussion, there is no cell proliferation or cell infiltration in the tissues. If the hyperaemia is persistent then there follows in due course hypertrophy. To avoid, however, making another group in classification I have grouped the erythematous diseases under the head of local inflammations. With regard to “squamous inflammation,” there is here only hyperaemia and hyperplasia or hypertrophy, and no actual inflammatory infiltration. Psoriasis, the type of the class, is on the borderland only of inflammation; but we will group it under inflammations for the present at all events.
The reader will very naturally want to be told wherein lies the differences between hypertrophy and hyperplasia following hyperaemia, on the one hand; and the changes that occur in the skin in zymotic diseases, and those that are observed in lupus, syphilis, and leprosy on the other hand; and what are the differences that lead dermatologists to make the special class of disease to be dealt with in this chapter. In the first place, with regard to the local changes in the zymotic diseases- as small-pox and typhoid-these are only parts of general malady, and could not be regarded in group characterized essentially by peculiarities of local change. From an etiological point of view it would be impossible to do so.
Then, in regard to lupus, syphilis, etc., there are certain anatomical characters and behaviors about the growths, which, no less than peculiar concomitants of associated constitutional states and the like, that mark them as belonging to a special class of neoplasmata or heterologous new formations. In regard to the distinction to be drawn between hyperplasia consequent on inflammation, and hypertrophy, the latter is much slower, even if the etiology be left out of view; there is in the one the escaped blood cells developing into the new tissue, and in the other the increased supply of blood and transuded serosity.
But the two have certain analogies, and it is difficult if not impossible to draw line between hypertrophy and inflammation. But further, it may be said- and this applies to tumors and special neoplasms, and lupus and syphilis- whilst the inflammatory infiltration is caused by some irritant, the tumor of heteroplastic neoplasm arises spontaneously, or from a specific cause acting generally and modifying heat, redness, pain, and swelling, and these “signs” acutely developed; there is less tendency to spontaneous cure with tumors; and lastly, the inflammatory exudations directly tend to the formation of pus.
Erythematous Disease.
The diseases which rank under this head as having simply erythema as their primary and only feature are exceedingly simple and well defined. They are three; erythema, roseola, and urticaria. These erythemata re characterized mainly by the occurrence of active hyperaemia of the longitudinal plexus of the skin (erythema), and its immediate consequences- for example, serous effusion- nothing more. In erythematous disease the redness my be rosy roseola), or bright red (erythema urticaria); in urticaria “wheals” are present. The erythema in these diseases is removable by pressure. Unlike the more common eruptive diseases of the skin, the erythemata exhibit the closest connection between local and constitutional phenomena. Febrile symptoms antecede and are relieved by the development of the erythema in the exanthemata, showing that the local skin changes are secondary, and only parts of a general disturbance which is primary. I shall include under this head sections of follicular hyperaemia, pellagra, and certain medicinal rashes.
Erythema.
The term erythema, used by itself, is the name of a symptom, not of a disease, and may be applied to any reddened or congested surface not accompanied with elevation, and may be produced by a variety of causes. There are, however, two well-marked affections, erythema multiforme and erythema nodosum, which are distinct morbid entities, and deserve careful consideration.
Erythema Multiforme.
The eruption of erythema multiforme is a diffused patch of redness over which circumscribed elevations, also red, are scattered. These elevations may be from an eighth to three- quarters of an inch in diameter. The small ones, according to size, may be called papules or tubercles, while the larger ones, which are always flattened, may assume the appearance of an elevated ring, around which a second or a third ring may develop. On the flattened tubercles, of medium size, vesicles are sometimes met with, and hemorrhagic effusions may also occur within them.
These lesions rarely persist for more than a few days, or at most a week or so, art the end of which time they gradually subside and disappear, leaving after them slight stains, which last a few days longer. After the disappearance of the first eruption, or even while it is still in full bloom, a second crop of lesions may come out, and after these a third, prolonging the trouble in this way for several weeks and even months. Two or more of the lesions mentioned may coexist, and the eruption may appear on any part of the surface, but as a rule it prefers the extremities. Slight febrile action may precede the development of the eruption, but it soon disappears, and there is rarely any accompaniment other than slight itching.
The causes of erythema multiforme are obscure; occasionally it appears due to errors of diet, and sometimes also to uterine disorder. The prognosis is favorable, so far as any trouble may result from the eruption; but when it is prolonged for weeks, as is sometimes the case, it proves very annoying. It attacks by preference the backs of the hands and feet, the arms, the legs, and the forehead. It is mostly an affection of children and young people. It attacks females more than males, and prevails in the spring and fall. Individuals who are troubled with it one year are apt to have it again at the same time in succeeding years. When occurring on the fingers it closely resembles chilblains. It may be commonly known by its superficial and protean character, and its symmetrical distribution.
Erythema Nodosum.
This is a much more important but also rarer affection than the preceding one. The disease is characterized by the eruption of reddish tumors, from the size of bean to that of a small egg, and usually situated upon the lower extremities, between the knee and ankle. For a day or two the depth of color increases, then becomes somewhat purplish, and with the “black-and-blue” appearance which accompanies hemorrhagic effusions, and finally passes into the stage of green and yellow like an ordinary bruise. A week or ten days may be occupied by these processes; and, as the color changes, diminution of size takes place, and in about two weeks complete resolution is effected. Suppuration very rarely occurs. The number of the nodes is usually limited to three or four, but may reach nine or ten, and may appear on the thighs and upper extremities as well as the parts already named. The swellings are usually a little painful for the first day or two, but not afterward. Relapses may prolong the disease for several months. Occasionally the eruption is ushered in by febrile action, but not in all cases. It usually occurs in young females, and is not unfrequently accompanied by menstrual derangement. In many cases, however, the eruption is preceded by or complicated with arthritic pains. This has led many writers to believe the affection to be more or less closely connected with rheumatism.
