Hyperkeratosis is a general term used to describe thickening of the stratum corneum, the outermost layer of the skin.
The affected skin is thickened and rough and can occasionally become painful. Hyperkeratosis can occur on any location, including inside the mouth, but is more common in areas that have chronic pressure and rubbing such as the hands and feet.
Hyperkeratosis is associated with an abnormally increased or tightly packed keratin in the stratum corneum. This thickening is often part of the skin’s normal protection against rubbing, pressure, and irritation, such as in the cases of corn, calluses, lichen simplex chronicus, or by a variety of other acquired or inherited conditions such as chronic eczema, warts, actinic keratosis, seborrheic keratosis, squamous cell carcinoma, warts, lichen planus, keratosis pilaris, palmoplantar hyperkeratosis, and epidermolytic hyperkeratosis.
The treatment of hyperkeratosis depends on the cause.
- Actinic keratosis, seborrheic keratosis and warts can be treated with cryotherapy using liquid nitrogen.
- Squamous cell carcinomas may need to be treated with surgical procedures or a chemotherapy agent.
- Hyperkeratosis related to chronic skin inflammation, such as chronic eczema, should first be treated with anti-inflammatory medications such as topical steroids and calcineurin inhibitors.
- Chronic hyperkeratosis not related to skin inflammation, such as keratosis pilaris, palmoplantar hyperkeratosis, calluses and corn, can be treated with topical medications that can soften and smooth the skin surface, including ammonium lactate, lactic acid, alpha hydroxyl acid, retinoids and urea. Callus and corns can also be manually or surgically filed down.