The most common cysts of the skin are the sebaceous, known also as steatomas, which result from obstruction of the ducts of sebaceous follicles, and accumulation therein of sebaceous secretion. They are found where these glands abound, and may attain the size of a hen’s egg or larger. They are frequently infected and suppurate, or their contents may undergo slow change and lose their original characteristics by the time they are evacuated. Peculiar changes occur in rare instances, since they may calcify, or their bases serve even for the development of cutaneous horns, while in the other direction they not infrequently undergo malignant degeneration. In some of these cysts a small opening can be found, through which, on pressure, fatty or butter-like contents can be exposed. When their contents begin to putrefy the odor becomes offensive.
Another variety of the skin cyst is the so-called atheromatous, which is more allied to the cutaneous dermoid, and whose contents are often nearly pure cholesterin. Sometimes they contain hair or other epithelial products. They occur usually in the scalp. These are essentially inclusion cysts and purely epiblastic products. When infected their contents putrefy and smell badly. (See [Fig. 88], [p. 285].)
Treatment.
—The treatment for any cysts of the skin consists in extirpation of the sac. It is sufficient to split them thoroughly with a sharp, curved bistoury, and then, on either side, to seize the edge of the divided sac with forceps and enucleate it. All this can be done under local anesthesia. The cavity should be thoroughly disinfected and not too tightly closed.
Under the name Cock’s peculiar tumor some English writers have alluded to the offensive ulcerated surface, with raised edges, which is left after the contents of these cysts have undergone putrefaction and escaped by breaking down of the surface. Such a lesion is on the border-land between mere ulceration and malignancy.
HYPERTROPHIES AND BENIGN TUMORS OF THE SKIN.
Corns.
—Clavi, or corns, vary in density. A soft corn differs from a hard one only in that it is located where it is softened by moisture of the parts. A hard corn is a reduplication or callosity, conical in shape, representing great hypertrophy, with condensation of surface epithelium. Beneath old lesions of this kind will frequently be found small cysts, while nerve fibers become entangled, and these little lesions are sometimes exceedingly sensitive. They frequently become inflamed, the process proceeding to suppuration or ulceration.
Bunions.
—When beneath such an indurated area of skin there forms an adventitious bursa, or a natural one becomes involved, the lesion is called a bunion. These are more frequent over the joints of the toes, where they sometimes cause intense discomfort. The bursæ sometimes connect with the joint cavity, and should one suppurate the other necessarily becomes involved. An infection of either of these lesions causes local and possibly fatal disturbance. I have seen death from pyemia follow infection of a bursa beneath a soft corn ([Fig. 106]).