SKIN DISEASES. These form a large and important class. In number they are very extensive, owing to the varied forms of morbid change which the skin texture may undergo, no less than to the different portions of the structure and its appendages which may be specially affected. Further, the modifications of the typical forms of these diseases which are to be observed have led to arrangements and classifications of very complex character and multiplied greatly their nomenclature. Skin diseases are regarded by the physician as of great importance, not only from the fact that morbid action in this texture must have a powerful influence on the general health and may bring in its train other maladies, but also because they are not unfrequently themselves the expression of constitutional conditions, inherited or acquired, the recognition of which is essential to their effectual treatment. In order to clearness of description it is necessary to make use of some method of classification. Various arrangements have been adopted by writers on the subject, but the following appears sufficient for the present purpose: —

I. Disorders of the secreting apparatus (of the sebaceous and sweat glands);
II. Disorders specially relating to nutrition (hypertrophies; atrophies; new formations; pigmentary changes);
III. Inflammatory affections (erythematous; papular; vesicular; pustular; squamous or scaly);
IV. Neuroses (nervous disorders);
V. Parasitic affections (animal; vegetable).

I. DISORDERS OF THE SECRETING APPARATUS.— (1) Of the Sweat Glands.—The chief morbid conditions are excessive sweating (hyperidrosis) and foetid sweating (bromidrosis). Excessive sweating is a symptom observed in various diseases, such as phthisis and rheumatic fever, but it may exist apart from such conditions, and either be general, affecting the whole body, or confined to a part, such as the axillae, head, hands, feet, or, as in some rare instances, the one half of the body. Some persons habitually perspire, often to a great extent, on making any effort, yet never appear to suffer in health, although the discomfort is considerable. Excessive perspiration may often be prevented by the habitual use of the cold bath, and by tonics, such as iron, quinine, strychnia, &c. Locally, the use of astringent lotions of vinegar or a weak solution of lead will also be of service. Bromidrosis or foetid sweating is often associated with the former condition, and it too may be general or local. It most frequently affects the feet, especially in those who have much fatigue, and is a source of much personal discomfort as well as of annoyance to others. It is apparently due to rapid decomposition in the perspiration which has saturated the stockings, and for its treatment it is essential that these should be frequently changed and the feet washed several times a day, dried carefully, and dusted with some antiseptic powder, such as boracic or salicylic acid mixed with starch or French chalk. Hebra recommends the application to the feet of a composition of equal parts of olive oil and litharge plaster spread upon linen and used twice a day.

(2) Of the Sebaceous Glands.— Seborrhoea is a term applied to describe an accumulation on the skin of the normal sebaceous secretion mixed up with dirt and forming scales or a distinct incrustation. On the head, where it is commonly seen, it may interfere with the nutrition of the hair and cause partial baldness. A form of this disease occurs in young infants. The main treatment is local, consisting in thorough cleansing of the parts. The crusts may be softened with oil and the affected skin regularly washed with soft soap and rectified spirit. The sebum frequently accumulates in the sebaceous ducts, giving rise to the minute black points so often noticed on the face, back, and chest in young adults, to which the term comedones is applied. A form of this disorder, but of larger size and white appearance, is termed milium. These affections may to a large extent be prevented by strict attention to ablution and brisk friction of the skin, which will also often remove them when they begin to appear. The retained secretion may be squeezed out or evacuated by incision and the skin treated with some simple sulphur application.

Acne is an eruption produced by inflammation of the sebaceous glands and hair follicles. It may occur in connexion with the preceding or independently, and shows itself in the form of red pimples or papules which may become pustular and be attended with considerable surrounding irritation of the skin. This affection is likewise most common in early adult life, and occurs on the chest and back as well as on the face, where it may, when of much extent, produce considerable disfigurement. It is apt to persist for months or even years, but usually in time disappears entirely, although slight traces may remain in the form of scars or stains upon the skin. Eruptions of this kind are sometimes produced by the continued internal use of certain drugs, such as the iodide or bromide of potassium. The treatment is similar to that for the previous affection, viz., brisk friction of the skin, short of producing irritation, and the application of a sulphur lotion or ointment. Attention to the general health by suitable diet, tonics, exercise, &c, is a necessary adjuvant. A variety of this malady, to which the name acne rosacea is given, is a more severe and troublesome disorder than that already mentioned. It is characterized by great redness of the nose and cheeks, accompanied with nodular enlargements on the surface of the skin, which produce marked disfigurement. Although often seen in persons who live too freely, it is by no means confined to such, but may arise in connexion with disturbances of the general health, especially of the function of digestion, and in females with menstrual disorders. It is apt to be exceedingly intractable to treatment, which is here too, as in the preceding form, partly local and partly constitutional. Of internal remedies preparations of iodine and of arsenic are sometimes found of service.

Molluscum contagiosum belongs to this class of skin diseases. It consists of an enlargement of the sebaceous glands and occlusion of the ducts, and is seen most commonly on the face, body, or hands in children, or on the breasts in women. It is said to be contagious, but it is a rare form of skin disease.

II. DISORDERS AFFECTING NUTRITION.— (1) Hypertrophies.—A corn (clavus) is a local thickening of the skin, generally occurring on the toes. There is hypertrophy of the epidermis, and in the centre of the corn there is usually a still denser mass, which, pressing down upon the subjacent sensitive true skin, causes pain and may give rise to inflammation and suppuration in the part. When situated between the toes the corn is softer than when on the free surface of the foot. The treatment consists in maceration of the hardened skin and the use of the knife or strong caustics. Salicylic acid combined with ether and collodion, painted over the part, is said to be useful in the case of soft corns.

A wart (verruca) is an excrescence from the surface of the skin due to hypertrophy of the papillary layer of the cutis and of the epidermis. This form of growth may also occur on mucous membranes. Warts occasionally disappear spontaneously, or they may be excised, or carefully touched with some strong caustic acid or alkali.

Ichthyosis or xeroderma consists of a general thickening of the whole skin and marked accumulation of the epidermic elements, with atrophy of the sebaceous glands, giving rise to a hard, dry, scaly condition. It generally first appears in infancy, and is probably congenital. It differs in intensity and in distribution in different cases, and is generally little amenable to any but palliative remedies, such as the regular application of oily sub-stances, although it is not a fatal malady.

For elephantiasis Arabum, see vol. viii. p. 126.





(2) Atrophies.—The chief of these relate to the hair. Canities or whitening of the hair consists in the non-formation of the pigmentary matter which is normally present in the substance of the hair, and occurs generally as a slow senile change. It may, however, take place prematurely, in which case it is often hereditary; or it may be associated with degenerative changes taking place in the system. It is occasionally seen to occur temporarily in very young persons in connexion with some defective condition of the general health. Its development suddenly has not unfrequently been observed as the result of some strong mental emotion.

Alopecia, or baldness, is the loss of hair, which is most commonly a senile change and irremediable, or on the other hand may be premature, occurring either hereditarily or in connexion with some previous constitutional morbid state (e.g., after fevers or other blood poisons), in which latter case it may be only, although not always, temporary. It appears to depend upon atrophic changes affecting the hair follicle, including obliteration of the capillary vessels,—the result of which is that strong hairs cease to be produced, and only feeble, short, and thin hair (lanugo) is formed, which soon falls off and is not reproduced. Usually the whole skin of the hairy scalp undergoes thinning and other atrophic changes as well as the hair follicle. Sometimes the loss of hair occurs in distinct circular patches (alopecia areata), which tend to spread until the whole scalp is denuded. The treatment of temporary or premature baldness bears reference especially to any known conditions affecting the general health; and tonics, baths, and other means to promote a vigorous skin function are useful. Stimulating liniments containing spirits and cantharides, the regular cleansing and moderate brushing of the parts, the application to the scalp of the constant current of electricity, and various other remedies appear to be of service in promoting the growth of hair.

(3) New Formations.—(a) Lupus is a disease characterized by the formation in the skin of tubercles or nodules consisting of new cell growth which has no tendency to further development, but to retrograde change, leading to ulceration and destruction of the skin and other tissues in which it exists, and the subsequent formation of permanent white scars. Lupus vulgaris is most commonly seen in early life, and occurs chiefly on the face, about the nose, cheeks, ears, &c, but it may also affect the skin of the body or limbs. It first shows itself in the form of small, slightly prominent nodules covered with thin crusts or scabs. These may be absorbed and removed at one point, but they tend to spread at another. Their disappearance is followed by a white permanent cicatrix. The disease may be superficial in which case both the ulceration and resulting scar are slight (lupus non-exedens); or, on the other hand, the ulcerative process may be deep and extensive, destroying a large portion of the tissues of the nose or cheeks, and leaving deep marks with much disfigurement (lupus exedens). Another form of this disease, termed lupus erythematosus, is of comparatively mild character, and occurs on the nose and adjacent portions of the cheeks in the form, of red patches covered with thin scales, underneath which are seen the widened openings of the sebaceous ducts,—this variety of the disease affecting specially that portion of the skin texture. It is very slow in disappearing, but does not leave any marked scar. Lupus is generally more frequently seen in women than in men, and it is held to be connected with a scrofulous constitution. Its treatment bears reference especially to this condition (see SCROFULA). In the superficial variety the application of soothing ointments when there is much redness, and Squire's method of slight linear incisions to destroy the increased blood supply, are often serviceable. In the ordinary form the great principle of local treatment is to remove the new tissue growth. This is most readily done either by solid points of caustic, of which the nitrate of silver is perhaps the best, thrust into the tubercles to break them up, or by means of a scoop (Volkmann's spoon) to scrape away the diseased masses. Only by such means can the ulceration be arrested and healing brought about.

(b) Leprosy (elephantiasis Graecorum) may be regarded as belonging to this class of skin diseases, inasmuch as it consists in a new growth of cell material, like lupus, but with less tendency to disintegration and with a wider distribution affecting the skin, mucous membranes, nerves, &c, all over the body. For its history and pathology see vol. xiv. p. 468 sq. Leprosy is not amenable to treatment, beyond attempts at palliation of the symptoms and by general hygiene.

(4) Pigmentary Changes.— Chloasma is an abnormal pigmentation, in the form of brown patches, either generally diffused or confined to one part, such as the forehead and face, and occasionally seen in women suffering from uterine ailments. Addison's disease is connected with a morbid condition of the suprarenal capsules (see PATHOLOGY), and is accompanied with general bronz-ing of the skin, together with anosmia and great and increasing prostration. Leukoderma is a change in the pigmentation of the skin, whereby it becomes white in patches, with a tendency to spread and affect almost the whole surface, until a few dark areas alone remain to represent the original appearance of the skin. It is sometimes called white leprosy, but has no relation to that disease, nor is it of any special significance as regards the health. Albinism is an entire absence of pigment from the hair, skin, eyes, &c. The hair is usually white, and the skin exceedingly pale ; and the eye has a pinkish appearance. This condition is congenital. It occasionally exists to a partial extent in any of the textures named.

III. INFLAMMATORY SKIN AFFECTIONS.—These embrace the following chief varieties:—(1) diffuse (erythema); (2) papular (lichen); (3) catarrhal (eczema); (4) vesicular (herpes, pemphigus); (5) pustular (impetigo); and (6) scaly (psoriasis, pityriasis).

(1) Diffuse.—This variety includes erythema (see ERYSIPELAS) and its forms, particularly erythema nodosum, which consists of spots and patches of dark red colour and slightly elevated, appearing on the front of the legs and back of the arms in young persons, mostly females. The patches continue for a number of days and then become fainter. It is supposed to be connected with rheumatism, joint pains not unfrequently accompanying it. Urticaria or nettle-rash is a diffuse redness of the skin, accompanied with wheals of raised and paler appearance, not unlike the effect produced by the sting of nettles or of insects, and attended with great irritation and itching. Certain kinds of food, such as fruit and fish, produce this eruption in some persons, as also some drugs, such as opium. It is best treated by some soothing application, such as a solution of sal volatile, to which a little chloral has been added, and by attention to the state of the alimentary canal. Roseola, which consists in the appearance of rose-coloured spots upon the body, is frequently seen in children, and is apt to be mistaken for measles, but has none of the accompanying febrile or catarrhal symptoms of that disorder, and is of brief duration.

(2) Papular.— Lichen, an eruption consisting of small, thickly-set, and slightly-elevated red points, more or less widely distributed over the body, and in the young somewhat resembling scarlet fever, but with only slight febrile symptoms and no sore throat, usually results from digestive derangements, but apparently may also arise from exposure to the sun, and it lasts but a short time. Some forms, however (e.g., lichen ruber), are of chronic character and difficult of treatment. The ordinary form requires little beyond attention to the digestive organs and the application of a soothing lotion or powder. The chronic forms are best treated by the administration of arsenic. Strophulus, or tooth-rash, or, as it is popularly termed, "red gum," an affection very common in young infants, belongs to this class of skin disorders.

(3) Catarrhal.— Eczema, one of the most common and important of all skin diseases, consists of an inflammation of the true skin, of catarrhal character, together with the formation of papules, vesicles, or pustules, attended with more or less discharge, and with itching and other symptoms of irritation. It may be either acute or chronic, and presents itself in a variety of forms. As regards causation, it appears impossible to assign any one condition as giving rise to this disease. It occurs frequently in persons to all appearance in perfect health, and it may in such cases be a permanent or recurring affection during a whole lifetime. Again it is undoubtedly found in persons who possess a morbid constitution, such as the gouty or scrofulous ; but apart from any such evident associations it seems in some instances itself distinctly hereditary. Sometimes it is set up as the result of local or general irritation of the skin in certain occupations, and it may exist in connexion with the presence of some other skin disease. It is much more common in men than in women. Numerous varieties of eczema are described, according to its site and duration; only the more important of these can be alluded to. Acute eczema shows itself by redness and swelling of the skin, with the formation of minute vesicles, and attended with severe heat and irritation. Should the vesicles rupture, a raw moist surface is formed, from which a colourless discharge oozes, which when it accumulates forms thin crusts. The attack may be general over the greater portion of the body, or it may be entirely localized to a limb or other part. It usually lasts for a few weeks and then passes off, leaving, however, a liability to recurrence. Such attacks may occur as a result of digestive derangements, or in persons of rheumatic or gouty habit, and they tend to appear at certain seasons, such as springtime. They are usually best treated by attention to the general health, and by a simple and carefully-regulated diet, while locally some soothing application, such as a weak lead lotion or a dusting powder of zinc, starch, or boracic acid, will be found of benefit. Chronic eczema shows itself in various forms, of which we note the most common. In eczema rubrum the disease affects a part, very often a limb, as a severe form of inflammation, with great redness, and weeping or oozing of serous matter from the raw surface. It gives rise to great irritation and pain, and may cause considerable disturbance of the general health. It may last for years, with intervals of partial recovery, but easily recurring. The skin of the limb becomes in time thickened and the limb itself much swollen. In dry eczema the skin, though irritable, remains dry and scaly. In pustular eczema, or eczema impetiginodes, in addition to the cutaneous inflammation there occur pustules which break and the purulent matter forms yellow crusts upon the skin. This form is very common on the heads of young children during the period of dentition. The treatment of chronic eczema depends in great measure upon the form it assumes. Where there exists much irritation, soothing lotions or applications similar to those required for acute eczema are necessary; but where irritation has subsided, stimulating ointments, such as those of zinc or white precipitate, are often of service. Constitutional remedies, such as iron, arsenic, &c, are an important and often essential part of successful treatment.





(4) Vesicular.— Herpes is an inflammation of the true skin, attended with the formation of isolated or grouped vesicles of various sizes upon a reddened base. They contain a clear fluid, and either rupture or dry up. Two well-marked varieties of herpes are frequently met with. (a) In herpes labialis et nasalis the eruption occurs about the lips and nose. It is seen in cases of certain acute febrile ailments, such as fevers, inflammation of the lungs, or even in a severe cold. It soon passes off. (b) In herpes zoster, zona, or shingles, the eruption occurs in the course of one or more cutaneous nerves, often on one side of the trunk, but it may be on the face, limbs, or other parts. It may occur at any age, but is probably more frequently met with in elderly people. The appearance of the eruption is usually preceded by severe stinging neuralgic pains for several days, and, not only during the continuance of the herpetic spots, but long after they have dried up and disappeared, these pains sometimes continue and give rise to great suffering. The disease seldom recurs. The most that can be done for its relief is to protect the parts with cotton wool or some dusting powder, while the pain may be allayed by opiates or bromide of potassium. Quinine internally is often of service.

Pemphigus consists in large blebs upon a red base. They contain clear or yellowish fluid. This disease appears to show itself most frequently on the bodies and limbs of unhealthy or neglected children. The blebs give rise to much irritation, and when they burst leave raw ulcerated surfaces which are slow of healing. One variety of this malady (pemphigus foliaceus) affects the entire skin of the body, from which there exudes a constant discharge. This form is apt sooner or later to prove fatal from its exhausting effects. The treatment is mainly constitutional,—by good nourishment, iron, &c.

(5) Pustular.— Impetigo, consisting of small pustules situated upon a reddened base, mostly occurs in children. There appears to be a contagious form of this malady. Ecthyma consists of large pustules of similar character on the body and limbs. The treatment of these ailments requires special attention to nutrition, since they usually occur in low states of health.

(6) Squamous or Scaly.— Psoriasis, an inflammatory affection of the true skin, attended with the formation of red spots or patches, which are covered with white silvery scales, may affect any portion of the surface of the body, but is most common about the elbows and knees, and on the head. There is as a rule comparatively little irritation except at the outset, but there is an extensive shedding of the scales from the affected spots. Varieties of this disease are described in relation to the size and distribution of the patches. The causes of psoriasis have given rise to much discussion, and, while some authorities regard its appearance as in many instances connected with some constitutional morbid state, such as gout, rheumatism, &c, the majority deny any such relationship, and mention hereditary influence as the only recognizable cause, although it must be admitted that even this evidence is wanting in a large number of cases. The disease appears to be consistent with continued good health. It is usually obstinate to treat, and may, with intervals of comparative immunity, last a lifetime. The remedies most serviceable are arsenic internally and the application externally of preparations of tar. Eecently the employment of chrysophanic acid as an ointment or in solution has been resorted to with considerable success.

Pityriasis, a superficial inflammation of the skin, with the formation of minute branny scales, occurs most commonly on the head, and is of chronic duration. The remedies most useful are alkaline lotions and tar preparations. A variety of this disease (pityriasis rubra) affects the whole body, and is most intractable to treatment.

IV. NEUROSES (Nervous Affections).— Various disorders of nutrition of the skin occur in persons suffering from organic nervous diseases, such as bedsores, atrophic changes, eruptions, &c, but these belong to the symptoms of the several diseases with which they are associated. The most common of the neuroses of the skin is probably pruritus, which is an ailment characterized by intense itching of the surface of the body. It may occur in connexion with other morbid conditions, such as jaundice, diabetes, digestive disorders, &c, or as the result of the irritation produced by lice or other skin parasites. The most serious form is pruritus senilis, which affects old persons, and is often a cause of great suffering, depriving the patient of sleep (the malady being specially trouble- some during the night). In such cases it is probably due to atrophic changes in the skin. No eruption is visible, except such marks as are produced by scratching. The treatment consists in the removal of any apparent cause, and measures to strengthen the system, such as the use of quinine, iron, &c. Soothing lotions composed of solutions of alkalis conjoined with chloral, opium, hydrocyanic acid, &c, may be applied to the affected skin at bedtime.

V. PARASITIC DISEASES.— (1) Animal.—The following are the chief animal parasitic diseases. Phthiriasis is produced by the presence of lice (pediculi), of which there are three varieties, infesting respectively the head, body, and pubis. The cause is in most instances uncleanliness, but occasionally in the aged, and in persons suffering from chronic diseases, there appears to be a liability to the development of pediculi, notwithstanding every care to prevent it. The irritation produced by the parasite and the scratching thus occasioned may give rise to abrasions of the skin and eczematous conditions. The treatment consists in thorough cleansing of the parts and the use of parasiticides, such as red or white precipitate, carbolic lotions (one in twenty), or a decoction or ointment of stavesacre. Where clothing is infested it should be destroyed or subjected to a strong heat to get rid both of the parasites and their ova. Scabies or itch is a skin affection due to the Acarus scabiei (see MITE). The female insects burrow into the upper layers of the skin and deposit their eggs in the tract thus made. Great irritation of the skin is set up, and scratching produces eruptions which aggravate the condition, especially at night. The most frequent sites are the parts between the fingers, or the wrists, but by scratching the disease may be conveyed to any part of the body, and in extreme cases the greater portion of the surface of the trunk and limbs may be involved. In infants the feet and buttocks are the parts which suffer. The eruption in mild cases has at first the appearance of small raised vesicles with clear fluid, but it may become pustular or eczematous, and extensive excoriations may result. The treatment consists in thorough cleansing of the skin and the inunction of some form of parasiticide,—sulphur ointment being on the whole the best. The application should be discontinued after a few days, otherwise irritation may be produced by its use.

(2) Vegetable parasites consist of fungous growths in the texture of the skin and hair, which are characterized microscopically by minute round bodies or spores often coalesced into clusters or bead-like arrangements, and jointed filaments or mycelium of elongate and branching form. They are readily detected by removing a hair, or scraping a portion of the affected skin, treating it with a strong alkaline solution, and submitting it to microscopic examination, by which the slight differences in form and arrangement of the varieties of the parasite can be easily made out. The common name "tinea" is applied to these parasitic affections. Tinea tonsurans, or ringworm (parasite Tricophyton tonsurans), is a very common form of parasitic disease. It occurs as a result of contagion in the heads of children, and begins as circular patches with a scaly appearance and red border, which tend to spread. The hair at the part becomes thin and brittle and is easily removed. It is often extremely obstinate to treatment, and numerous agents have been proposed as specifics, not one of which, however, appears to possess infallible virtues. Among the best are oleate of mercury (5 to 10 per cent.) and other mercurial preparations, all which, however, must be used with care, and carbolic or sulphurous acid with glycerin, iodine, cantharides, &c; but isolation of the patient as far as possible, together with strict medical supervision, are essential for the effectual treatment of this disorder. Tinea sycosis, or ringworm affecting the beard, and tinea circinata, or ringworm affecting the body, require to be dealt with in a similar manner. Tinea favosa, or favus (parasite Achorion Schönleinii), is less frequently seen than the preceding. It occurs mostly on the scalp in unhealthy and neglected children, but it may affect the skin in any part of the body. It is characterized by round, yellow, sulphur-coloured, cup-shaped spots or crusts, which, when occurring extensively upon the scalp, have a peculiar mousy odour. It is very destructive of hair growth, and is most difficult to cure. The best treat- ment is removal of the hairs by epilation, and the employment of some of the parasiticides already mentioned, together with attention to the healthy nutrition of the patient. Tinea versicolor, or pityriasis versicolor (parasite Microsporon furfur), is a brown-coloured rash of scaly character occurring mostly in the form of spots or patches on the skin of the trunk, particularly on the front of the chest or between the shoulders, but sometimes also upon the arms and legs. It affects adults in whom the skin-function is not sufficiently attended to, or those who are in ill-health. The parasite affects the epidermic cells, and is readily made out by the microscope, thus enabling the disease to be distinguished from other skin disorders to which it often bears resemblance. It is best treated by the regular washing and brisk friction of the parts, and by the use of some of the applications above referred to. (J. O. A.)



The above article was written by: J. O. Affleck, M.D.