Hyperkeratosis is the term to describe thickening of keratin in the epidermis, which is the outer layer of the skin. Keratin is a protein found in the outer layers of the skin that helps to protect the body.
Hyperkeratosis usually occurs in areas of skin that have been irritated or subject to significant pressure, although it can affect any area of the skin. In some cases, a genetic susceptibility may be responsible for causing hyperkeratosis. It can have a varied appearance, depending on the form and cause:
- Corns and calluses: these are formed by the buildup of dead skin cells due to frequent rubbing, often on the hands or feet
- Warts: these are small bumps, usually on the hands and feet, caused by human papillomavirus (HPV)
- Chronic eczema: this condition is due to inflammation of the skin caused by allergies, irritants or other triggers
- Lichen planus: patches inside the mouth (white) or on the skin (purplish-blue) due to an abnormal immune response
- Actinic keratosis: flat, red patches on the skin caused by excessive exposure to ultraviolet radiation from sunlight
- Epidermiolytic hyperkeratosis: thick, scaly skin in a large area that is caused by a genetic mutation
Hyperkeratosis is painless in most cases, although it can cause discomfort, such as when there are corns, calluses or warts in sensitive areas of the skin. Other symptoms may include hair loss and discoloration of the skin.
The diagnosis of hyperkeratosis typically includes a consultation about the medical and family history of the individual, in addition to an examination of the skin.
It is important to know if there is a family history of certain skin conditions, which may increase the likelihood of an individual being affected by hereditary conditions. Other factors that may be relevant include exposure to sunlight, use of smokeless tobacco, eating habits and dentures.
The skin examination will look for particular characteristics that are definitive of the forms of hyperkeratosis. In some cases, further tests or a skin biopsy may be required. This helps to make an accurate diagnosis and enable the appropriate therapy to be carried out.
The choice of treatment depends on the type and location of hyperkeratosis.
For example, discomfort from corns and calluses may be relieved by the application of padding to the affected area. For seborrheic keratosis, the affected area may be removed with a scalpel or with a procedure known as cryosurgery, which freezes the area with liquid nitrogen. Warts and actinic keratosis may be removed with cryosurgery or laser therapy.
Topical agents used in the treatment of hyperkeratosis may include:
- Salicylic acid to break up the keratin, causing the thick skin to soften and be shed, thus reducing the thickness of the skin.
- Urea-based agents to increase the content of water in the skin and soften the area. This can help to break up the keratin, although to a lesser extent than salicylic acid.
- Alphahydroxy acid to exfoliate the skin and remove the hardened layers, uncovering softer layers underneath, which accept moisture more readily.
- Tretinoin to stimulate the shedding of skin that has become too thick.
- Corticosteroid cream for lichen planus, eczema and some other forms.
The prognosis for hyperkeratosis is usually very good. Rarely, actinic keratosis can lead to squamous cell skin cancer.
There are several methods to prevent the various forms of hyperkeratosis, including tips such as:
- Wear comfortable, well-fitted shoes to improve foot health and prevent the formation of corns and calluses on the feet
- Avoid using public locker rooms and restrooms without shoes to prevent warts on the feet
- Avoid the use of harsh soaps, deodorants and other chemical triggers to reduce the severity of eczema