There is a natural hesitation to excise keloid because of the fear of its returning in the new scar.  The application of radium is, so far as we know, the only means of preventing such return.  The irritation associated with keloid may be relieved by the application of salicylic collodion or of salicylic and creosote plaster.

Epithelioma is liable to attack scars in old people, especially those which result from burns sustained early in childhood and have never really healed.  From the absence of lymphatics in scar tissue, the disease does not spread to the glands until it has invaded the tissues outside the scar; the prognosis is therefore better than in epithelioma in general.  It should be excised widely; in the lower extremity when there is also extensive destruction of tissue from an antecedent chronic ulcer or osteomyelitis, it may be better to amputate the limb.

AFFECTION OF THE NAILS

Injuries.—­When a nail is contused or crushed, blood is extravasated beneath it, and the nail is usually shed, a new one growing in its place.  A splinter driven underneath the nail causes great pain, and if organisms are carried in along with it, may give rise to infective complications.  The free edge of the nail should be clipped away to allow of the removal of the foreign body and the necessary disinfection.

Trophic Changes.—­The growth of the nails may be interfered with in any disturbance of the general health.  In nerve lesions, such as a divided nerve-trunk, the nails are apt to suffer, becoming curved, brittle, or furrowed, or they may be shed.

Onychia is the term applied to an infection of the soft parts around the nail or of the matrix beneath it.  The commonest form of onychia has already been referred to with whitlow.  There is a superficial variety resulting from the extension of a purulent blister beneath the nail lifting it up from its bed, the pus being visible through the nail.  The nail as well as the raised horny layer of the epidermis should be removed.  A deeper and more troublesome onychia results from infection at the nail-fold; the infection spreads slowly beneath the fold until it reaches the matrix, and a drop or two of pus forms beneath the nail, usually in the region of the lunule.  This affection entails a disability of the finger which may last for weeks unless it is properly treated.  Treatment by hyperaemia, using a suction bell, should first be tried, and, failing improvement, the nail-fold and lunule should be frozen, and a considerable portion removed with the knife; if only a small portion of the nail is removed, the opening is blocked by granulations springing from the matrix.  A new nail is formed, but it is liable to be misshapen.

Tuberculous onychia is met with in children and adolescents.  It appears as a livid or red swelling at the root of the nail and spreading around its margins.  The epidermis, which is thin and shiny, gives way, and the nail is usually shed.