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 accumulations. 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 horny 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 mass 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 horny layer.
State the prognosis of callositas.