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, Carbolic.-Erythema.
Acid, Salicylic.-Erythema, vesicles, papules, and wheals
Aconite.-Erythema and vesicles.
Antimony.-Vesicles and pustules.
Antipyrin.-Papules.
Arnica.-Erythema, bullae, and scales.
Arsenic.-Erythema, papules, vesicles, bullae, pustules, and wheals.
Belladonna.-Erythema.
The Bromides.-Erythema, vesicles, bullae, pustules, papules, tubercles, and wheals.
Cannabis Indica.-Vesicles.
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.
Naphthalin.-Papules.
Phosphorus.-Bullae.
CLASSIFICATION OF THE ELEMENTARY LESIONS.
Santonin-Papules, vesicles, and wheals.
Sulphonal-Macules, papules.,
Sulphur-Erythema and vesicles.
Violet-water (locally)- Papules.
Pathology
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.
