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.
