Mollusc.u.m epitheliale is characterized by pin-head to pea-sized, rounded, semi-globular, or flattened, pearl-like elevations, of a whitish or pinkish color.

Describe the symptoms and course of mollusc.u.m epitheliale.

The usual seat is the face; not infrequently, however, the growths occur on other parts. The lesions begin as pin-head, waxy-looking, rounded or ac.u.minated elevations, gradually attaining the size of small peas. They have a broad base or occasionally may tend to become pedunculated. They rarely exist in profusion, in most cases three to ten or twelve lesions being present. When fully developed they are somewhat flattened and umbilicated, with a central, darkish point representing the mouth of the follicle. They are whitish or pinkish, and look not unlike drops of wax or pearl b.u.t.tons. At first they are firm, but eventually, in most cases, tend to become soft and break down. Not infrequently, however, the lesions disappear slowly by absorption, without apparent previous softening. Their course is usually chronic. The contents, a cheesy-looking ma.s.s, may commonly be pressed out without difficulty.

What is the cause of mollusc.u.m epitheliale?

It is now generally accepted that the disease is mildly contagious. It occurs chiefly in children, and especially among the poorer cla.s.ses. The belief in the parasitic nature of the disease is gaining ground; recently the opinion has been advanced that it is due to psorosperms (psorospermosis); but further investigations have indicated that these bodies were degenerated epithelia.

State the pathology.

[Ill.u.s.tration: Fig. 31. Mollusc.u.m Epitheliale.]

According to recent investigations, mollusc.u.m epitheliale is to be regarded as a hyperplasia of the rete, the growth probably beginning in the hair-follicles; the so-called mollusc.u.m bodies--peculiar, rounded or ovoidal, sharply-defined, fatty-looking bodies found in microscopical examination of the growth--are to be viewed as a form of epithelial degeneration.

What are the diagnostic points in mollusc.u.m epitheliale?

The size of the lesions, their waxy or glistening appearance, and the presence of the central orifice.

It is to be differentiated from mollusc.u.m fibrosum, warts and acne.

State the prognosis.

The growths are amenable to treatment. In some instances the disease, after existing some weeks, tends to disappear spontaneously.

What is the treatment of mollusc.u.m epitheliale?

Incision and expression of the contents, and touching the base of the cavity with silver nitrate. Pedunculated growths may be ligated. In some cases an ointment of ammoniated mercury, twenty to forty grains to the ounce, applied, by gently rubbing, once or twice daily, will bring about a cure.

Callositas.

(_Synonyms:_ Tylosis; Tyloma; Callus; Callous; Callosity; Keratoma.)

What do you understand by callositas?

A hard, thickened, h.o.r.n.y patch made up of the corneous layers of the epidermis.

Describe the clinical appearances.

Callosities are most common about the hands and feet, and consist of small or large patches of dry, grayish-yellow looking, hard, slight or excessive epidermic acc.u.mulations. They are somewhat elevated, especially at the central portion, and gradually merge into the healthy skin. The natural surface lines are in a great measure obliterated, the patches usually being smooth and horn-like.

_Keratosis palmaris et plantaris_ (symmetric keratodermia), as regards the local condition, is a somewhat similar affection. It consists of hypertrophy of the corneous layer of the palm and soles, usually of a more or less h.o.r.n.y and plate-like character, but is congenital or hereditary, and not necessarily dependent upon local friction or pressure.

Are there any inflammatory symptoms in callositas?

No; but exceptionally, from accidental injury, the subjacent corium becomes inflamed, suppurates, and the thickened ma.s.s is cast off.

State the causes of callositas.

Pressure and friction; for example, on the hands, from the use of various tools and implements, and on the feet from ill-fitting shoes. It is, indeed, often to be looked upon as an effort of nature to protect the more delicate corium.

In exceptional instances it arises without apparent cause.

What is the pathology?

The epidermis alone is involved; it consists, in fact, of a hyperplasia of the h.o.r.n.y layer.

State the prognosis of callositas.

If the causes are removed, the acc.u.mulation, as a rule, gradually disappears. The effect of treatment is always rapid and positive, but unless the etiological factors have ceased to act, the result is usually but temporary.

How is callositas treated?

When treatment is deemed advisable, it consists in softening the parts with hot-water soakings or poultices, and subsequently shaving or sc.r.a.ping off the callous ma.s.s. The same result may also be often effected by the continuous application, for several days or a week, of a 10 to 15 per cent. salicylated plaster, or the application of a salicylated collodion, same strength; it is followed up by hot-water soaking, the acc.u.mulation, as a rule, coming readily away.

Clavus.

(_Synonym:_ Corn.)

What is clavus?

Clavus, or corn, is a small, circ.u.mscribed, flattened, deep-seated, h.o.r.n.y formation usually seated about the toes.

Describe the clinical appearances.

Ordinarily a corn has the appearance of a small callosity; the skin is thickened, polished and h.o.r.n.y. Exceptionally, however, occurring on parts that are naturally more or less moist, as between the toes, maceration takes place, and the result is the so-called _soft corn_. The dorsal aspect of the toes is the common site for the ordinary variety.

The usual size is that of a small pea. They are painful on pressure, and, at times, spontaneously so.

State the causes.

Corns are caused by pressure and friction, and may usually be referred to improperly fitting shoes.