Unless a removal of the exciting or predisposing cause is possible, the prognosis is, as a rule, unfavorable, and the relief furnished by local applications usually but temporary.

If const.i.tutional treatment is advisable, upon what is it to be based?

Upon general principles; there are no special remedies.

How do external remedies act?

Mainly by removing the rete cells and with them the pigmentation; and partly, also, by stimulating the absorbents.

Are all external remedies which tend to remove the upper layers of the skin equally useful for this purpose?

No; on the contrary some such applications are followed by an increase in the pigment deposit.

Name the several applications commonly employed.

Corrosive sublimate in solution, in the strength of one to four grains to the ounce of alcohol and water; a lotion made up as follows:--

[Rx] Hydrargyri chlorid. corros., ......... gr. iij-viij Ac. acet. dilut., .................... f[dram]ij Sodii borat., ........................ [scruple]ij Aquae rosae, ........................... f[Oz]iv. M.

And also the following:--

[Rx] Hydrargyri chlorid. corros., ......... gr. iij-viij Zinci sulphat., Plumbi acetat., ...... [=a][=a] ...... [dram]ss Aquae, ................................ f[Oz]iv. M.

And lactic acid, with from five to twenty parts of water; and an ointment containing a drachm each of bis.m.u.th subnitrate and white precipitate to the ounce. Hydrogen peroxide occasionally acts well.

Trichloracetic acid, usually weakened with one or two parts water, may be cautiously tried. The application of a strong alcoholic solution of resorcin, twenty to fifty per cent. strength, is also valuable, as is also a two to ten per cent. alcoholic solution of salicylic acid.

(Applications are made two or three times daily, and as soon as slight scaliness or irritation is produced are to be discontinued for one or two days.)

_Tattoo-marks_ are difficult to remove. Excision is the surest method.

Electrolysis, applying the needle at various points, somewhat close together, and using a fairly strong current--three to eight milliamperes--will exceptionally, especially when repeated several times, produce a reactive inflammation and casting-off of the tissue containing the pigment; a scar is left.

Several writers claim good results with glycerole of papain, p.r.i.c.king it in in the same manner as in tattooing.

_Gun-powder marks._ If recent, but a day or so after their occurrence, the larger specks may be picked or sc.r.a.ped out. Later, electrolysis, using a fairly strong current, may result in their removal. Their removal may also be satisfactorily effected with a minute cutaneous trephine.

Keratosis Pilaris.

(_Synonyms:_ Pityriasis Pilaris; Lichen Pilaris.)

What is meant by keratosis pilaris?

Keratosis pilaris may be defined as a hypertrophic affection characterized by the formation of pin-head-sized, conical, epidermic elevations seated about the apertures of the hair follicles.

Describe the clinical appearances of keratosis pilaris.

The lesions are usually limited to the extensor surfaces of the thighs and arms, especially the former. They appear as pin-head-sized, whitish or grayish elevations, consisting of acc.u.mulations of epithelial matter about the apertures of the hair follicles. Each elevation is pierced by a hair, or the hair may be twisted and imprisoned within the epithelial ma.s.s; or it may be broken off just at the point of emergence at the apex of the papule, in which event it may be seen as a dark, central speck.

The skin is usually dry, rough and harsh, and in marked cases, to the hand pa.s.sing over it, feels not unlike a nutmeg-grater. The disease varies in its development, in most cases being so slight as to escape attention. As a rule, it is free from itching.

What course does keratosis pilaris pursue?

It is sluggish and chronic.

Mention some of the etiological factors.

It is not an uncommon disease, and is seen usually in those who are unaccustomed to frequent bathing, being most frequently met with during the winter months. It is chiefly observed during early adult life.

Is there any difficulty in the diagnosis?

No. It is thought at times to bear some resemblance to goose-flesh (cutis anserina), the miliary papular syphiloderm in its desquamating stage, and lichen scrofulosus. In goose-flesh the elevations are evanescent and of an entirely different character; the papules of the syphiloderm are usually generalized, of a reddish color, tend to group, are more solid and deeply-seated, less scaly and are accompanied with other symptoms of syphilis; in lichen scrofulosus the papules are larger, incline to occur in groups, and appear usually upon the abdomen.

State the prognosis.

The disease yields readily to treatment.

Give the treatment of keratosis pilaris.

Frequent warm baths, with the use of a toilet soap or sapo viridis, will usually be found curative. Alkaline baths are also useful. In obstinate cases the ordinary mild ointments, glycerine, etc., are to be advised in conjunction with the baths.

Keratosis Follicularis.

Describe keratosis follicularis.

Keratosis follicularis (_Darier's disease_, _ichthyosis follicularis_, _ichthyosis sebacea cornea_, _psorospermosis_) is a rare disease characterized by pin-head to pea-sized pointed, rounded, or irregularly-shaped grayish, brownish, red or even black, h.o.r.n.y papules or elevations, arising from the sebaceous or hair-follicles. They are, for the most part, discrete, with a tendency here and there to form solid aggregations or areas. Many of them contain projecting cornified plugs which may be squeezed out, leaving pit-like depressions. The face, scalp, lower trunk, groins and flanks are the parts chiefly affected.

The view advanced by Darier, that the malady was due to psorosperms, is now denied, the bodies thought to be such having been demonstrated to be due to cell transformation.

As to treatment, in one instance the induction of a subst.i.tutive dermatic inflammation had a favorable influence.

Mollusc.u.m Epitheliale.

(_Synonyms:_ Mollusc.u.m Contagiosum; Mollusc.u.m Sebaceum; Epithelioma Mollusc.u.m.)

Give a definition of mollusc.u.m epitheliale.