The first step in diagnosis is to obtain a clear and full understanding of the different lesions, so that their true character may be recognized at a glance. Each author has a pet classification which he honestly believes to be the best. One divides them into 1. Maculae; 2. Erythematous; 3. Papular; 4. Vesicular; 5. Pustular; 6. Squamous; 7. Tubercular; 8. Parasitic.
Another gives 1. Masculae or stains; 2. Erythema or redness; 3. Wheals; 4. Papules, or pimples; 5. Squammae or scales; 6. Vesicles, or little bladders; 7. Blebs, or large vesicles; 8. Tubercula, or lumps; 9. Pustules, or mattery heads.
I have found the following division to be of the greatest help in diagnosing skin affections: Macules, Vesicles, Bullae, Pustules, Papules, Tubercles, Scales, Fissures, and Ulcers.
There is one remark I would make with a view of helping the reader to avoid a common error in regard to these lesion. It is this, that the different typical forms of lesions embrace or include each of them several varieties, and the designation of each typical form or lesion is to be regarded as a generic term, applicable to several varieties of the same lesion. It is not enough, for instance, to say a papule is present. Since there are various kinds of papules, it is necessary to state what particular kind of pustule is meant. When it is said a tubercle is present, the class to which the lesion belongs has only been defined; the tubercle may be that of a cancer, lupus, or syphilis. I am convinced that one of the commonest errors into which those who are studying skin diseases fall is the neglect to recognize the fact that there are several different varieties of the same kind of elementary lesions, and their confusion of these several different varieties. This is especially the case with papules. We will describe the several varieties of elementary lesions.
A macule is a small, circumscribed portion of skin, in which has occurred some alternation in its color, but without any secretion, effusion, infiltration, or change in its thickness or consistence. The macule itself may be white from loss of pigment, red from congestion, or dark or black from increase of pigment.
The principal diseases in which it occurs, and chief features, are:
1. Chloasma, in which the macule or discoloration is somewhat diffuse, occurring on the forehead and cheeks, and is of a brownish color.
2. Erythema; The macules are of varying size of a reddish color.
3. Ephelis; Macules of a yellowish to a dark brown color. Chiefly found on the exposed parts of the body.
4. Lentigo; Small, dark-brown macules scattered over the surface, on the covered as well as on the uncovered portions.
5. Lentigo maligna; Very dark macules, from the size of a large pin-head to that of a pea, later becoming infiltrated, and sometimes ulcerating.
6. Leprosy; Brownish macules of varying size.
7. Leucoderma; White or light-pinkish macules, surrounded by a dark border.
8. Lupus; Minute reddish-brown or ham-colored.
9. Naevus; Red or purplish, disappearing on firm pressure.
10. Purpura; Red or purplish, not disappearing on pressure.
11. Rosacea; Rosy macules.
12. Syphilis (a) Reddish macules, appearing in early syphilis, chiefly on the chest, abdomen and back; (b) Macules resembling those of leucoderma, and met with about the neck in young women in the early period of the disease.
13. Xanthelasma; Yellowish macules, chiefly met with about the eyelids. A vesicle is a small elevation of the horny layer of the epidermis, by the effusion of a serous fluid.
The principal diseases in which vesicles are found, and their chief features, are:
1. Eczema; In patches, minute and closely aggregated, and rupturing in a day or two, except where the epidermis is very thick.
2. Dermatitis multiformis; Lesions of larger size and greater duration, and frequently accompanied with other lesions of a pustular character.
3. Erysipelas; Lesion situated on a diffused inflamed base, usually on the face.
4. Erythema multiforme; Associated with macules and patches of erythema.
5. Herpes; One or more groups of three or four vesicles of moderate size, and not packed together so closely as in eczema. They usually last a few days, and dry brown into a small scale or crust, except on the genitals, where they rupture promptly.
6. Impetigo contagiosa; Medium-sized vesicles, lasting a few days and drying down to form crusts, occurring on any part of the body.
7. Scabies; Small, pointed vesicles, usually met with on the hands and fingers.
8. Sudamina; Minute, disseminated vesicles, corresponding to the sudoriparous ducts.
9. Varicella; Vesicles of medium size, which may or may not be umbilicated.
10. Variola; Umbilicated vesicles succeeding papules.
11. Zoster; Vesicles of good size, seated on inflamed patches, and following the course of a nerve-trunk.
A bulla is a larger elevation of the epidermis, by a serous or sero-fibrinous effusion, than a vesicle.
The principal diseases in which bullae are found, and their chief features are:
1. Erysipelas; The bullae of erysipelas are in reality very large vesicles, seated on the inflamed base.
2. Leprosy; Large bullae, usually solitary, and appearing at intervals.
3. Pemphigus; Large bullae, solitary, or in crops at intervals.
A pustule is an elevation of the epidermis, small or large, by a purulent exudation.
The principal diseases in which pustules are found, and their chief features are:
1. Acne; Small, scattered pustules, resulting from the suppression of papules, chiefly met with on the face, back, and chest.
2. Ecthyma; Scattered pustules, of medium size.
3. Eczema; Closely aggregated pustules, of small size.
4. Dermatitis multiformis; Pustules associated with other lesions.
5. Furuncles; A pustule seated at the apex of an inflamed, painful, and slightly elevated spot.
6. Scabies; Isolated pustules, especially frequent about the hands and wrists.
7. Syphilis; Pustules succeeding papules; or occurring without them.
8. Variola; Umbilicated pustules which follow vesicles, and which were preceded by papules, discrete or confluent.
The common feature of these three lesions-vesicle, bulla, pustule-is a fluid exudation-serous, sero-fibrinous, or purulent- which lifts up a greater or less extent of horny epidermis, producing an elevation on the skin, and the lesion consists of an effused fluid, kept in bounds by a limiting membrane.
A vesicle, bulla, or pustule having formed may further progress in one of several ways. After a few days the effusion may be reabsorbed without rupture of the epidermis, and leave nothing but a loosely attached scale, which soon exfoliates. On the other hand, the epidermis may rupture in a day or two, the effusion be poured out, and the whole dry up to a small crust, which in a few days more is wholly detached; or, still again, a vesicle or pustule may rupture promptly, but from the denuded surface a serous or purulent fluid may continue to exude for several days or even weeks.
A papule is a small, solid elevation of the skin. In this case the exudation into the skin is of a plastic character, mostly cells with but little fluid effusion-not sufficient, in fact, to produce a vesicle. A papule may disappear in a few days by absorption of the exudation, or may be gradually converted into a pustule; or may undergo ulceration, or may even persist without alteration almost indefinitely.
The principal diseases in which papules are found, and their chief features are:
1. Acne; Papules of varying size, chiefly met with on the face, shoulders, back, and chest, and frequently changing into pustules.
2. Erythema multiforme; Grouped papules, most frequent on the extremities.
3. Eczema; Scattered, or more or less closely aggregated, on the arms, inside of thighs, and elsewhere, frequently accompanied with scratch-marks.
4. Lichen simplex; Scattered papules, frequently met with over the entire surface.
5. Lichen planus; Flat, umbilicated, papules, greatly resembling those of a papular syphilide.
6. Lupus; Persistent and gradually increasing in size; becoming tubercles, usually on the face.
7. Milium; Minute white papules on the eyelids and contiguous skin.
8. Molluscum contagiosum; Umbilicated papules, containing a cheesy matter which may be pressed out, frequently pedunculated-in this respect differing from acne papules, which are not pedunculated.
9. Prurigo; Hard, and under or in the skin, not much elevated, and with little change in color of the skin; more easily felt than seen, and accompanied with scratching marks.
10. Rubeola; Red papules, covering the entire surface, and accompanied with febrile symptoms.
11. Scabies; Small papules, usually accompanied with other lesions, and generally with their apices scratched off.
12. Strophulus; Red papules, in infancy only.
13. Syphilis; More or less generalized reddish or copper- colored; may degenerate into pustules, or become covered with a fine scale.
14. Urticaria; Large papules, lasting a few hours only, but succeeded at short intervals by others, and accompanied with sharp pruritus.
15. Variola; Discrete or confluent, changing into vesicles, and later into umbilicated pustules; usually accompanied with severe general symptoms.
16. Xanthelasma; Yellowish and slightly elevated, most frequent about the eyes, but may occur elsewhere.
A tubercle is a solid elevation of the skin, larger than a papule, but agreeing with it in other respects and capable of undergoing the same changes-namely, absorption, pulsation, ulceration, or indefinite prolongation.
The principal diseases in which tubercles are found, and their chief features are:
1. Acne; Tubercles on face, back, etc., with inflamed bases, and usually terminating with suppuration.
2. Fibroma; Single or multiple, and scattered over all parts of the body.
3. Framboesia; Fungous tubercles, frequently of large size- very rare.
4. Keloid; Flat tubercles, or flattened elevations of the skin, with projecting finger-like processes.
5. Lentigo maligna; Commencing as macules, becoming papules, and afterward tubercles, frequently with ulceration.
6. Leprosy; Reddish-brown tubercles on the forehead, ears, and other parts of face and body.
7. Lupus; Solitary of but few reddish-violet tubercles, of very slow increase, and terminating with ulceration.
8. Morphoea; Flat, light-colored tubercles, followed by atrophy, from one to a dozen- rarely more.
9. Rosacea hypertrophica; Confined to the nose.
10. Syphilis; Copper-colored, terminating with suppuration or ulceration. In early syphilis, numerous; in late syphilis, number of lesions limited, and occurring in groups.
Scales are collections of cells of the stratum corneum, which, instead of pursuing their usual and normal course, collect in undue number and quantity, and are loosely or firmly attached to the skin in more or less heaped-up masses. When these scales are small in size, loosely attached, like a fine powder or meal scattered over the surface, they are termed farinaceous; on the other hand, when large, thick, heaped up, and firmly attached, they are called furfuraceous.
The principal diseases in which scales are found, and their chief features are:
1. Dermatitis exfoliativa; Large scales, consisting of flakes of horny epidermis; sometimes several inches in extent.
2. Eczema; Medium size, scales occurring in the last stage of the disease, and frequently preceded by exudation and crusting.
3. Ichthyosis; Very adherent thick scales, the disease commencing in early life and continuing indefinitely.
4. Lupus erythematosus; Very fine adhering scales, situated on a reddened, infiltrated base.
5. Pemphigus foliaceus; Large scales, due to imperfect formation of bullae.
6. Pityriasis simplex; Fine white scales on a surface but little affected otherwise, and readily exfoliating.
7. Pityriasis rubra; Fine scales on a reddened surface, usually generalized.
8. Psoriasis; Thick, adherent, imbricated white scales on a reddened infiltrated surface, more or less generalized.
9. Syphilis; Small scales at the summit of papules, or thicker and larger on reddened infiltrated surface, more or less generalized.
10. Trichophytosis capitis; Fine scales among hair-stumps on round patches.
Fissures are solutions of continuity, and are characterized by varying length and depth, but with scarcely appreciable breadth. They rarely extend deeper than through the horny or Malpighian layers, though sometimes they penetrate the cutis vera. They are frequently accompanied with a scanty serous exudation.
The principal diseases in which fissures are found, and their chief features are:
1. Eczema; Especially at flexor aspect of joints, palms of the hands, and soles of the feet.
2. Leprosy; Especially at extensor aspect of small joints or between them, and usually accompanied with anaesthesia.
Ulcers are solutions of continuity of three dimensions- namely, length, breadth, and depth. Their borders may be sharp cut and perpendicular to the skin, or may be sloping or overhanging, features which often afford a valuable clue to the origin of the lesion.
The principal diseases in which ulcers are found, and their chief features are:
1. Carcinoma; Ulceration on the elevated surface of a carcinomatous tumor; underlying tissues hard.
2. Lupus; Ulceration following one or more tubercles, sometimes becoming carcinomatous.
3. Scrofula; Irregular and uneven, frequently with overhanging margins.
4. Syphilis; Round or ovoid, with straight “punched-out” margins.
5. Simple; Round or oval, with sloping margins Tumors:
1. Carcinoma (epithelioma); Usually solitary, hard, and terminating by ulceration.
2. Elephantiasis; Sometimes immense tumors of the genitals, which in rare instances have reached the weight of one hundred pounds.
3. Fibroma; Solitary or multiple, of varying size, sessile of pedunculated, without tendency to ulceration.
4. Papilloma; Warty tumors, of varying size and number.
5. Sarcoma; Soft “fleshy” tumors, bleeding readily; usually solitary, unless accompanied with melanotic deposit.
6. Steatoma; Enlarged sebaceous glands, with retention of secretion.
In addition to the above there are certain other lesions, some of which are secondary, while others are peculiar to certain special diseases, and will be described in connection with them.
With the foregoing list of diseases and lesions, and with their chief peculiarities visible at a glance, there should be but little difficulty in working out an analytical diagnosis in the great majority of cases of cutaneous disease. We would, however, advise the student to pursue the following course: First, determine the predominant lesion, then turn to the list of diseases which are characterized by that lesion, and see how closely the descriptions there given agree with the appearances presented; and, when a choice is made, carefully read the description of the disease itself as found in later pages of the book. Should the disease in question present more than one lesion, examine the lists of diseases under each lesion, and proceed as before. Several years’ experience in studying dermatology has satisfied the writer that the pursuit of the method here laid down will enable the student to become a prompt and correct diagnostician in a surprisingly short time. He will, of course, meet with cases in which he will not succeed, but he should remember that cases not infrequently occur which puzzle even the most expert.
The subject of diagnosis, however, cannot be dismissed without allusion to certain eruptions or rashes that arise, not spontaneously, but after the ingestion of certain drugs that have been administered for other disease. The following named drugs have been known to give rise to the lesions which follow their titles, viz.:
Acid, Salicylic.-Erythema, vesicles, papules, and wheals
Aconite.-Erythema and vesicles.
Antimony.-Vesicles and pustules.
Arnica.-Erythema, bullae, and scales.
Arsenic.-Erythema, papules, vesicles, bullae, pustules, and wheals.
The Bromides.-Erythema, vesicles, bullae, pustules, papules, tubercles, and wheals.
Chloral.-Erythema, papules, vesicles, and wheals.
Cinchona derivatives.-Erythema, papules, vesicles, and wheals.
Copaiba.-Erythema, papules, vesicles, bullae, and wheals.
Digitalis.-Erythema and wheals.
Hyoscyamus.-Erythema and wheals.
The Iodides.-Erythema, papules, vesicles, bullae, pustules, and wheals.
Iodoform.-Erythema, papules, and vesicles.
CLASSIFICATION OF THE ELEMENTARY LESIONS.
Santonin-Papules, vesicles, and wheals.
Sulphur-Erythema and vesicles.
Violet-water (locally)- Papules.
The pathology of the skin presents no essential differences from the pathology of other pars of the body-that is, the same morbid process that are met with elsewhere also find expression in the dermal tissues. For instance, congestion, inflammation hypertrophy, atrophy, oedemas, infiltrations, degenerations, neoplasms, pseudo-plasms, nervous derangements, etc., are the processes which result in the production of the various lesions that constitute the essential visible characteristics of cutaneous disease. In addition we have certain parasitic invasions, of both animal and vegetable origin. The complex structure of the skin, and of the special organs contained in it, together with the anatomical peculiarities of the appendages, give rise to an almost infinite variety of changes.