Hyperkeratosis

Pathologists use the term hyperkeratosis to describe a thickening of the skin caused by an increased number of specialized squamous cells in the skin’s outer layer. This outer layer, called the keratin layer, consists of strong, flat cells that help protect the underlying skin. Hyperkeratosis is a non-cancerous (benign) condition considered a descriptive finding rather than a specific diagnosis.

What does the keratin layer normally do?

The keratin layer forms a protective barrier that helps shield the skin from injury, infection, and moisture loss. The thickness of this layer naturally varies in different parts of the body. For instance, the keratin layer is much thicker on the soles of the feet and palms of the hands, where more protection is needed, compared to thinner areas such as the chest or face.

What causes hyperkeratosis?

Hyperkeratosis typically occurs due to chronic irritation, friction, pressure, inflammation, or certain skin conditions. Common causes include:

• Chronic friction or pressure: Areas of repeated friction (such as feet or hands) often develop hyperkeratosis, commonly known as calluses or corns.

• Skin conditions: Conditions such as eczema, psoriasis, lichen planus, or actinic keratosis (sun damage) may lead to hyperkeratosis.

• Exposure to ultraviolet (UV) radiation: Chronic sun exposure can cause the skin to thicken, resulting in hyperkeratosis.

How is hyperkeratosis diagnosed?

Hyperkeratosis is typically diagnosed by a pathologist who examines a skin sample under a microscope. When hyperkeratosis is present, the pathologist sees a thicker-than-normal keratin layer due to the increased number of cells.

It’s important to note that hyperkeratosis is not a specific diagnosis; rather, it is a descriptive term used to identify changes in the skin. Your doctor will consider this finding, along with other clinical information and any additional tests, to determine the underlying cause.

Is hyperkeratosis harmful?

Hyperkeratosis itself is not harmful or cancerous. However, it may indicate underlying skin irritation or inflammation needing attention or treatment. In some cases, long-standing hyperkeratosis (such as from chronic sun exposure) may lead to precancerous conditions, like actinic keratosis, which requires monitoring and treatment.

How is hyperkeratosis treated?

Treatment depends on the underlying cause of the hyperkeratosis:

• Reducing friction: Padding, footwear adjustments, or protective gloves can reduce friction-induced hyperkeratosis (calluses).

• Topical treatments: Moisturizers, exfoliants (such as salicylic acid), or creams can help manage skin conditions associated with hyperkeratosis.

• Medical treatments: Prescription creams or procedures like cryotherapy may be necessary for precancerous conditions like actinic keratosis.

Questions to ask your doctor

• What might be causing the hyperkeratosis on my skin?

• Is the hyperkeratosis a sign of an underlying skin condition?

• Do I need any treatment, or should I monitor the area?

• How can I prevent or reduce hyperkeratosis in the future?

• Should I be concerned about this turning into something more serious, such as skin cancer?