ETIOLOGY



Besides the constitutional conditions just mentioned, the eruptive fevers, syphilis, pyemia, septicemia, scurvy and malaria present characteristic cutaneous eruptions. Chronic or severe forms of malaria may produce melanotic staining of the skin, herpes and urticaria; less often, erythema and purpura; and rarely, furuncles and carbuncles. The gastrointestinal tract is the seat of many digestive disturbances which develop ferments and toxins. These processes constitute auto-intoxication and bear a direct causal relation to acne, rosacea, seborrhea, eczema, psoriasis, the erythemata and many other reflex disorders. The relation of food in quality and quantity to disorders of the digestive system and the resulting skin eruptions is most important. Infant foods, containing undigested starch, are frequent sources of cutaneous eruptions in young children; but, at any age, food may be an important factor. individual idiosyncrasies in respect to one or more articles of diet may also have a direct causal relation. Diabetes predisposes strongly to the formation of furuncles, carbuncles, cachectic acne, urticaria and erythema. It may produce a characteristic papulopustular eruption (xanthoma diabeticorum) without subjective symptoms, but which rapidly disappears with the relief of the underlying disease. Pruritus, especially about the genital regions, is frequently caused by diabetes. Of rarer occurrence are the superficial and terminal gangrenes of the skin, which occur sometimes in the advanced stages of the same disease. Eczema, purpura, urticaria and general pruritus are occasionally observed in the course of chronic nephritis in old people. In the advanced stages, there sometimes appears upon the skin an erythema, which, at first, may resemble measles or scarlet fever, but the patches of eruption soon coalesce and may become generally diffused. Desquamation in large flakes follows, leaving the skin infiltrated, red and sometimes eczematous. This uremic eruption is of grave prognostic significance and resembles dermatitis exfoliativa.

Spasmodic asthma is so frequently observed in association with eczema, acne, urticaria and ichthyosis that it may be considered causal. Lithemia and jaundice are common causes of persistent pruritus, with or without a secondary dermatitis. Chronic jaundice, from whatever origin, frequently stands in etiological relation to existing multiple xanthoma; while simple xanthoma of the eyelids, in the majority of cases, is secondary to migraine. Incidentally, this shows how the same pathological disease in different clinical forms may arise from widely divergent causes.

Chronic constipation may cause chloasma or the rare affection, chromidrosis. Chloasmatic patches occur not infrequently as above stated, in pregnancy, from uterine derangements, and occasionally as symptoms of an abdominal cancer or a contracted liver. The general staining of the skin from Addison’s disease or from Graves’ disease (exophthalmic goitre) is well known. Senile pigmented patches are sometimes due to degeneration of the skin. While neurotic disturbances frequently determine the location and extent of a cutaneous eruption, the latter expression is by no means constant, nor its character uniform, if we except the varieties of zoster which are believed to be due to an inflammation of some part of the nerve trunk or ganglion, having terminations in the affected area. Nervous shocks, such as great fright, grief, etc., occasionally transmit of the trophic nerve impressions powerful enough to cause bleaching of the hair, baldness, eczema and psoriasis. However, all of these diseases may follow other and quite different causes. Marked variation in the degree of nutrition resulting in plethora or anemia, if persistent, may cause a predisposition to disease. Plethora tends to superficial congestions and inflammations of the skin, and is apt to make them less tractable to treatment. Overfed, indolent and stagnant individuals are more liable to attacks of eczema, pruritus, etc., from trivial causes. The debilitated or anemic are more prone to seborrhea, furuncles, carbuncles ecthyma and impetigo than those who are well nourished. Defective nutrition and impaired functions of the skin probably have much to do with the lodgment and growth of parasites, the invasion of pathogenic germs or the absorptions of contagion. Thus some persons are easily infected by contact, while others remain wholly immune after exposure. This difference in the avoidance of disease can only be explained by general or local loss of vigor, by some anatomical peculiarity or by a change in quantity or quality of the protective secretions of the skin.

The ingestion of certain drugs, in small or large doses, may produce nearly all the elementary eruptions of the skin. With few exceptions, drug eruptions are not a constant effect or uniformly characteristic. Eruptions caused by quinine, copaiba, belladonna, iodine, bromine, chloral and many others drugs, will be referred to in detail under dermatitis medicamentosa. The element of personal idiosyncrasy should be constantly borne in mind when the consideration of a drug eruption is necessary.

EXCITING INFLUENCES

The etiological relations of climate, seasons and habitation have already been briefly mentioned but they may be considered as exciting factors in some dermatoses although for the most part their action is upon the health or nutrition.

Personal Hygiene. Filth and uncleanness are undoubtedly exciting factors in dermatological practice but when compared with skin diseases arising from occupation, overindulgences of all sorts, mental and nervous worry and the manifold responsibilities of modern life, they are not as frequently noted as supposed. So it happens that defects in personal hygiene are not limited to the poor and neglected but involve the cleanly and well nourished, not to mention the luxurious in as great a proportion, although the items of unhygienic living are those of plenty rather than want. The lack of soap and water bathing is noticeable in the causation of acne, seborrhea and keratosis pilaris, while the too free use of the same agents may excite milaria, erythema, intertrigo, dermatitis and eczema. The indiscriminate use of water, especially when combined with impure soaps and vigorous scrubbing, is not only to be condemned for the vigorous but may be expected to aggravate almost any pre-existing skin eruption. Clothing may assume an exciting role. Too many or too thick clothes easily causes a miliaria in infants, especially during hot weather. Soiled underclothing, long worn, favors the development of eczema and seborrhea of the body. Too light or too coarse garments, or the presence of irritating dyes in clothing, may excite erythema, dermatitis, excoriations and pruritus.

Chemical and Mechanical Factors. Chemical substances, applied externally, may excite irritation, inflammation or destroy the superficial and deep layers of the skin. The degree of injury will depend upon the nature of the irritant, the duration of the application and the sensitiveness of the part involved. Agents of this class are very numerous; they include many plants which contain an active principle deleterious to the skin such as arnica, ivy, sumac, mustard, etc.; most of the etheral oils and resins; the poisons introduced into the skin by the stings and bites of insects and reptiles such as bees, mosquitoes and snakes; the various antiseptic preparations, when carelessly or freely used, such as iodoform, mercuric chloride, phenol and creolin; substances used in the process of manufacturing dyes as the aniline preparations; strong acids as nitric, muriatic, sulphuric, acetic and lactic; the stronger alkalies as caustic potash; the effects of heat from unusual exposure to sun-rays, overexposure to X-rays, radiation from heaters or flames, or actual contact, and also the extremes of cold. To these might be added the effects of chemicals used in various trades, frequently unavoidable, and especially the many medicated applications, often unnecessary. It should always be remembered that chemical irritants may not be limited in their effects to the area of the skin directly acted upon; but, through their influence on innervation, may cause disturbances at distant points or, by lessening the resistance of the skin, permit other agents to act more readily. Regarding this relation of medicinal irritants, Kaposi has well said that “these relations are altogether too little known for, if they were, physicians would not use cutaneous irritants so indiscriminately.”

Mechanically acting agents are often chemical in their action at the same time. They are incidental to nearly every active employment of mankind and may act to produce changes in the epidermis or deeper portions of the skin. In fact, the effects of occupation trade eruptions, professional or occupations dermatitis are quite common. Plain water may cause a surface irritation if used for long periods or often. Active exercise which commonly promotes health, if too long continued without protection of the surface, may cause chafing and consequent dermatitis. Fissured eczema is common in plasterers, masons and wash-women, whose hands are frequently brought in contact with alkalies. Those who handle animals or animal substances, as herdsmen, tanners and butchers, are most liable to anthrax and ecthyma. Occupations necessitating exposure to heat, as with cooks, blacksmiths and firemen, are favorable to attacks of erythema, eczema and dermatitis; while workers at oil refining, tar distillation and in aniline color making, etc., are peculiarly subject to dermatitis. Intermittent pressure, incident to the trade of shoemakers, blacksmiths, etc., produces thickening of the corneous layer of the epidermis, known as callous; while prolonged pressure over a point, as from a tight shoe, may produce a corn. Tight bands and garters may obstruct the local circulation, causing swelling of the skin or enlargement of the veins. Among the many other unmentioned causes of mechanical irritation, one group needs special notice excoriations from scratching with the finger- nails and all sorts of accidental abrasions, bruises and lacerations of the skin.

Frederick Dearborn
Dr Frederick Myers DEARBORN (1876-1960)
American homeopath, he directed several hospitals in New York.
Professor of dermatology.
Served as Lieut. Colonel during the 1st World War.
See his book online: American homeopathy in the world war