What is the pathology of clavus?

It is a hypertrophy of the epiderm. Its shape is conical, with the base external and the apex pressing upon the papillae. It is, in fact, a peculiarly-shaped callosity, the central portion and apex being dense and h.o.r.n.y, forming the so-called core.

Give the treatment of clavus.

A simple method of treatment consists in shaving off, after a preliminary hot-water soaking, the outer portion, and then applying a ring of felt or like material, with the hollow part immediately over the site of the core; this should be worn for several weeks. It is also possible in some cases to extract the whole corn by gently dissecting it out; the after-treatment being the same as the above.

Another method is by means of a ten- to fifteen-per-cent. solution of salicylic acid, in alcohol or collodion, or the following:--

[Rx] Ac. salicylici, ...................... gr. x.x.x Ext. cannabis Ind., .................. gr. x Collodii, ............................ f[dram]iv. M.

This is painted on the corn night and morning for several days, at the end of which time the parts are soaked in hot water, and the ma.s.s or a greater part of it, will be found, as a rule, to come readily away; one or two repet.i.tions may be necessary. Lactic acid, with one to several parts of water, applied once or twice daily, acts in a similar manner.

Soft corns, after the removal of pressure, may be treated with the solid stick of nitrate of silver, or by any of the methods already mentioned.

In order that treatment be permanently successful, the feet are to be properly fitted. If pressure is removed, corns will commonly disappear spontaneously.

Cornu Cutaneum.

(_Synonyms:_ Cornu Humanum; Cutaneous Horn.)

What is cornu cutaneum?

A cutaneous horn is a circ.u.mscribed hypertrophy of the epidermis, forming an outgrowth of h.o.r.n.y consistence and of variable size and shape.

At what age and upon what parts are cutaneous horns observed?

They are usually met with late in life, and are mostly seated upon the face and scalp.

[Ill.u.s.tration: Fig. 32.

Cutaneous Horns. Showing beginning epitheliomatous degeneration of the base. (_After Pancoast._)]

Describe the clinical appearances.

In appearance cutaneous horns resemble those seen in the lower animals, differing, if at all, but slightly. They are hard, solid, dry and somewhat brittle; usually tapering, and may be either straight, curved or crooked. Their surface is rough, irregular, laminated or fissured, the ends pointed, blunt or clubbed. The color varies; it is usually grayish-yellow, but may be even blackish. As commonly seen they are small in size, a fraction of an inch or an inch or thereabouts in length, but exceptionally attain considerable proportions. The base, which rests directly upon the skin, may be broad, flattened, or concave, with the underlying and adjacent tissues normal or the papillae hypertrophied; and in some cases there is more or less inflammation, which may be followed by suppuration. They are usually solitary formations. They are not, as a rule, painful, unless knocked or irritated.

What course do cutaneous horns pursue?

Their growth is usually slow, and, after having attained a certain size, they not infrequently become loose and fall off; they are almost always reproduced.

What is the cause of these h.o.r.n.y growths?

The cause is not known; appearing about the genitalia, they usually develop from ac.u.minated warts. They are rare formations.

State the pathology of cornu cutaneum.

Horns consist of closely agglutinated epidermic cells, forming small columns or rods; in the columns themselves the cells are arranged concentrically. In the base are found hypertrophic papillae and some bloodvessels. They have their starting-point in the rete mucosum, either from that lying above the papillae or that lining the follicles and glands.

Does epitheliomatous degeneration of the base ever occur?

Yes.

State the prognosis.

Cutaneous horns may be readily and permanently removed.

What is the treatment?

Treatment consists in detachment, and subsequent destruction of the base; the former is accomplished by dissecting the horn away from the base or forcibly breaking it off, the latter by means of any of the well-known caustics, such as caustic potash, chloride of zinc and the galvano-cautery.

Another method is to excise the base, the horn coming away with it; this necessitates, however, considerable loss of tissue.

Verruca.

(_Synonym:_ Wart.)

What is verruca?

Verruca, or wart, is a hard or soft, rounded, flat, ac.u.minated or filiform, circ.u.mscribed epidermal and papillary growth.

Name the several varieties of warts met with.

Verruca vulgaris, verruca plana, verruca plana juvenilis, verruca digitata, verruca filifortnis and verruca ac.u.minata.

Describe verruca vulgaris.

This is the common wart, occurring mostly upon the hands. It is rounded, elevated, circ.u.mscribed, hard and h.o.r.n.y, with a broad base, and usually the size of a pea. At first it is smooth and covered with slightly thickened epidermis, but later this disappears to some extent, the hypertrophied papillae, appearing as minute elevations, making up the growth. One, several or more may be present.

Describe verruca plana.

This is the so-called flat wart, and occurs commonly upon the back, especially in elderly people (_verruca senilis_, _keratosis pigmentosa_).