Persistent and slowly progressive.

[Ill.u.s.tration: Fig. 66.

Achorion Schonleinii X 450. (_After Duhring._) Showing simple mycelium, in various stages of development, and free spores.]

What are the symptoms of favus when seated upon the general surface?

The symptoms are essentially similar to those upon the scalp, modified somewhat by the anatomical differences of the parts.

The _nails_, when affected, become yellowish, more or less thickened, brittle and opaque (_tinea favosa unguium_, _onychomycosis favosa_).

To what is favus due?

Solely to the invasion of the cutaneous structures, especially the epidermal portion, by the vegetable parasite, the _achorion Schonleinii_. It is contagious. It is a somewhat rare disease in the native-born, being chiefly observed among the foreign poor. The nails are rarely affected primarily.

It is also met with in the lower animals, from which it is doubtless not infrequently communicated to man.

What are the diagnostic features of favus?

The yellow, and often cup-shaped, crusts, brittleness and loss of hair, atrophy, and the history.

[Ill.u.s.tration: Fig. 67. Epilating Forceps.]

How would you distinguish favus from eczema and ringworm?

From eczema by the condition of the affected hair, the atrophic and scar-like areas, the odor, and the history. From ringworm by the crusting and the atrophy. In this latter disease there is usually but slight scaliness, and rarely any scarring.

Finally, if necessary, a microscopic examination of the crusts may be made.

State the method of examination for fungus.

A portion of the crust is moistened with liquor pota.s.sae and examined with a power of three to five hundred diameters. The fungus, (achorion Schonleinii), consisting of mycelium and spores, is luxuriant and is readily detected.

State the prognosis of favus.

Upon the scalp, favus is extremely chronic and rebellious to treatment, and a cure in six to twelve months may be considered satisfactory; in neglected cases permanent baldness, atrophy, and scarring sooner or later result. Although favus of the scalp persists into adult life, it becomes less active and, finally, as a rule, gradually disappears, leaving behind scarred or atrophic bald areas.

Upon the general surface it usually responds readily to treatment, excepting favus of the nails, which is always obstinate.

How is favus of the scalp treated?

Treatment is entirely local and consists in keeping the parts free from crusts, in epilation and applications of a parasiticide.

The crusts are removed by oily applications and soap-and-water washings.

The hair on and around the diseased parts is to be kept closely cut, and, when practicable, depilation, or extraction of the affected hairs, is advised; this latter is, in most cases, essential to a cure. Remedial applications--the so-called parasiticides--are, as a rule, to be made twice daily. If an ointment is used, it is to be thoroughly rubbed in; if a lotion, it is to be dabbed on for several minutes and allowed to soak in.

Name the most important parasiticides.

Corrosive sublimate, one to four grains to an ounce of alcohol and water; carbolic acid, one part to three or more parts of glycerine; a ten per cent. oleate of mercury; ointments of ammoniated mercury, sulphur and tar; and sulphurous acid, pure or diluted. The following is valuable:--

[Rx] Sulphur, praecip., .................... [dram]ij Saponis viridis, Ol. cadini, ....... [=a][=a] ......... [dram]j Adipis, .............................. [Oz]ss. M.

Chrysarobin is a valuable remedy, but must be used with caution; it may be employed as an ointment, five to ten per cent. strength, as a rubber plaster, or as a paint, a drachm to an ounce of gutta-percha solution.

Formalin, weakened or full strength, has been extolled. Some observers have experimentally tried the effect of _x_-ray exposure with alleged good results, pushing the treatment to the point of producing depilation; if used great caution should be exercised.

How is favus upon the general surface to be treated?

In the same general manner as favus of the scalp, but the remedies employed should be somewhat weaker. In favus of the nail frequent and close paring of the affected part and the application, twice daily, of one of the milder parasiticides, will eventually lead to a good result.

Is const.i.tutional treatment of any value in favus?

It is questionable, but in debilitated subjects tonics, especially cod-liver oil, may be prescribed with the hope of aiding the external applications.

Tinea Trichophytina.

(_Synonym:_ Ringworm.)

What is tinea trichophytina?

Tinea trichophytina, or ringworm, is a contagious, vegetable-parasitic disease due to the invasion of the cutaneous structures by the vegetable parasite, the trichophyton, or the microsporon Audouinii.

Do the clinical characters of ringworm vary according to the part affected?

Yes, often considerably; thus upon the scalp, upon the general surface, and upon the bearded region, the disease usually presents totally different appearances.

Describe the symptoms of ringworm as it occurs upon non-hairy portions of the body.

Ringworm of the general surface (_tinea trichophytina corporis_, _tinea circinata_) appears as one or more small, slightly-elevated, sharply-limited, somewhat scaly, hyperaemic spots, with, rarely, minute papules, vesico-papules, or vesicles, especially at the circ.u.mference.

The patch spreads in a uniform manner peripherally, is slightly scaly, and tends to clear in the centre, a.s.suming a ring-like appearance. When coming under observation, the patches are usually from one-half to one inch in diameter, the central portion pale or pale red, and the outer portion more or less elevated, hyperaemic and somewhat scaly. As commonly noted one, several or more patches are present. After reaching a certain size they may remain stationary, or in exceptional cases may tend to spontaneous disappearance. At times when close together, several may merge and form a large, irregular, gyrate patch.

Itching, usually slight, may or may not be present.

Exceptionally ringworm appears as a markedly inflammatory pustular circ.u.mscribed patch, formerly thought to be a distinct affection and described under the name of _conglomerate pustular folliculitis_. It consists of a flat carbuncular or kerion-like inflammation, somewhat elevated, and usually a dime to silver dollar in area. The most common seats are the back of the hands and the b.u.t.tocks. The surface is cribriform, and a purulent secretion may be pressed out from follicular openings.

[Ill.u.s.tration: Fig. 68.

Tinea trichophytina cruris--so-called eczema marginatum--of unusually extensive development. (_After Piffard._)]