A corn or callous is the common name for what is generally termed hyperkeratosis. This is the action of an increase in the growth of the outer layer of skin due, in this case, to some trauma such as pressure or friction. It is observed on the hands of manual workers or in the feet when there is abnormal pressure from footwear, or abnormality of the feet themselves. There is no major difference between corns and callouses, their structure is very similar. Their appearance, thickness, size and density are all due to the variation in stresses that cause the resultant hyperkeratosis. Callouses generally cover a larger area and are of an even thickness whereas corns are moulded by pressure into a rough conical shape with a nucleus, the shape and size of which depends on the position and amount of pressure. They do not, as most people seem to believe, have roots.
There are various types of corns, characterised by their size and position and causative stresses.
1) Hard Corns. These are the most common type of corn, appearing on the top, and the tips of the toes, on the bottom of the foot, between the toes and even under the nail or down the sides of the nail. Treatment would consist of paring away the callous with a scalpel, digging out the nucleus, padding and advice. The only real cure for this or any type of corn is the removal of the cause, i.e. remove the pressure or friction and the corn will not form again.
Minor callosity due to pressure from footwear
2) Soft Corns. These are the same as hard corns only made soft by excessively sweaty or wet feet causing maceration of the skin. They appear nearly always between the toes and are white, soggy and rubbery due to the moisture. The shape depends on where between the toes they occur, if over the inside of the toe joint, the shape of the bone would dictate the shape of the corn. The main cause of this type of corn is the pressure from footwear squeezing the toes together. Treatment would be an astringent chemical to help dry out the macerated tissue, appropriate padding and, as with hard corns, removal of the pressure or friction.
3) Vascular corns. These are either hard or soft corns but unfortunately they have blood vessels within the strata of the corn. These blood vessels are forced into the growing corn by the squeezing or pinching effect of footwear causing a kind of ‘herniation’ of the dermis. (Underlying layer of skin containing blood vessels, sweat glands nerves etc.)
Neuro-vascular corn with bursitis
4) Neuro-vascular corns. As above, however there is the added presence of nerve tissue as well as blood vessels forming within the growing corn. These types can be very painful and often become inflamed. Treatment is much the same as for hard corns but is made more complicated due to the presence of peripheral blood vessels and nerves.
5) Seed corns. These corns are unlike all the others, they are caused not by pressure or friction, but apparently by callous building up around beads of cholesterol, or other intrinsic anomaly within the sole of the foot. They often occur on none weight bearing surfaces, or on weight bearing surfaces amidst a widespread area of callous that needs to be removed before they are simply picked out using a scalpel. Fortunately, these types of corn do take much longer to grow back than the other types.
Advice and treatment is best sought from a competent practitioner. Often, corns can be mistaken for verrucae and vice versa. Self- treatment is unadvisable, especially with the elderly and diabetic patients. Corn plasters are definitely not advised due to the caustic effects of the chemical within. Frankly, they are dangerous and use by the elderly or diabetic person can prove fatal.
