Overview of Corns
Corns, also called helomas, are thickened areas of skin that form in response to excessive pressure and friction. They form to protect the skin and the structures beneath it from damage or injury. Corns are usually hard and circular, with a waxy or translucent center. They may become painful or ulcerated in response to persistent friction.
Types of Corns
There are two types of corns. Hard corns (heloma durums) are the most common type. They are caused primarily by ill-fitting shoes and toe deformities. They usually develop on the tops and tips of the toes and on the sides of the feet. Soft corns (heloma molles) usually occur as the result of bone abnormalities in the toes. They develop between the toes and are sometimes referred to as "kissing corns."
In many people, the toes curl downward and do not lie flat. Fitting curled toes into shoes with tight toe boxes is the most common cause of hard corns. The toes remain curled inside the shoe and press against the inside of the shoe, usually at the toe joints. Additionally, the tip of the curled toe presses against the sole of the shoe. The skin compensates for this added pressure by thickening at the point of contact and hard corns develop to protect the underlying structure.
Soft corns typically develop between the fourth and fifth toes when one of the toe bones (phalanges) is slightly too wide. Normally, phalanges are hourglass-shaped and the ends are wider than the middle. Soft corns result when the ends of the toe bones are too wide, causing friction in between the toes. This problem is aggravated by tight-fitting shoes.
People with normal toe bones can also develop soft corns. This condition is especially common in women who wear high-heeled shoes with narrow, tapering toe boxes. These shoes shift the body's weight to the front of the foot and often do not provide enough room for the toes.