(Synonyms: Cornu Humanum; Cutaneous Horn.)

What is cornu cutaneum?

A cutaneous horn is a circumscribed hypertrophy of the epidermis, forming an outgrowth of horny 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.

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 papillÆ 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 horny growths?

The cause is not known; appearing about the genitalia, they usually develop from acuminated 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 papillÆ and some bloodvessels. They have their starting-point in the rete mucosum, either from that lying above the papillÆ 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.