Corns and calluses
Usually located on areas of repeated trauma (most often the feet), corns and calluses are acquired skin conditions marked by hyperkeratosis of the stratum corneum. The prognosis is good with proper foot care.
A corn is a hyperkeratotic area that usually results from continuous external pressure such as that from ill-fitting shoes. Less commonly, it results from internal pressure such as that caused by an underlying congenital or acquired bone deformity (from arthritis, for example).
A callus is an area of thickened skin, generally found on the foot or hand, produced by continuous external pressure or friction. Persons whose activities produce repeated trauma (for example, manual laborers or guitarists) commonly develop calluses.
The severity of a corn or callus depends on the degree and duration of trauma.