Callosities and corns
Calluses are a cutaneous reaction to chronic injury. Damaged skin responds with a hyperplastic response. That hyperplasia induces a thickening of the skin which is termed a callus.
Typically, calluses appear at points of pressure on the feet, and in the case of manual workers and some athletes, on the hand, and elsewhere.
Calluses on the feet act, in turn, like a pebble in the shoe. The thickened skin becomes a focal point for more injury. The skin becomes thicker yet, inducing more damage, and the cycle continues.
Significant hyperproliferation of keratinocytes leads to a very thick area of hyperkeratosis. Weight compresses this hyperkeratotic area driving out air, causing the development of a transparent clavus ("corn"). The corn in turn continues this injury and further hyperkeratosis is the result.
- Treatment of the callus is to remove the cause of injury. Calluses do not occur in the absence of trauma.
- The callus itself responds to 40% salicylic acid plasters, changed every two to three days, with the underlying skin pared each time.
- Corns respond to the same treatment, but the paring is deeper. As the corn moves up and out of the skin, the pain of the corn is reduced.
- Control of the problem depends on avoiding the source of external trauma, be it ill fitting shoes, and occupational or recreational damage.